xref: /openbmc/qemu/hw/i386/intel_iommu.c (revision 28cf553afeb29b0c4f339c600171552a72a68cb7)

/*
 * QEMU emulation of an Intel IOMMU (VT-d)
 *   (DMA Remapping device)
 *
 * Copyright (C) 2013 Knut Omang, Oracle <knut.omang@oracle.com>
 * Copyright (C) 2014 Le Tan, <tamlokveer@gmail.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.

 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.

 * You should have received a copy of the GNU General Public License along
 * with this program; if not, see <http://www.gnu.org/licenses/>.
 */

#include "qemu/osdep.h"
#include "qemu/error-report.h"
#include "qemu/main-loop.h"
#include "qapi/error.h"
#include "hw/sysbus.h"
#include "exec/address-spaces.h"
#include "intel_iommu_internal.h"
#include "hw/pci/pci.h"
#include "hw/pci/pci_bus.h"
#include "hw/qdev-properties.h"
#include "hw/i386/pc.h"
#include "hw/i386/apic-msidef.h"
#include "hw/boards.h"
#include "hw/i386/x86-iommu.h"
#include "hw/pci-host/q35.h"
#include "sysemu/kvm.h"
#include "sysemu/sysemu.h"
#include "hw/i386/apic_internal.h"
#include "kvm_i386.h"
#include "migration/vmstate.h"
#include "trace.h"

/* context entry operations */
#define VTD_CE_GET_RID2PASID(ce) \
    ((ce)->val[1] & VTD_SM_CONTEXT_ENTRY_RID2PASID_MASK)
#define VTD_CE_GET_PASID_DIR_TABLE(ce) \
    ((ce)->val[0] & VTD_PASID_DIR_BASE_ADDR_MASK)

/* pe operations */
#define VTD_PE_GET_TYPE(pe) ((pe)->val[0] & VTD_SM_PASID_ENTRY_PGTT)
#define VTD_PE_GET_LEVEL(pe) (2 + (((pe)->val[0] >> 2) & VTD_SM_PASID_ENTRY_AW))
#define VTD_PE_GET_FPD_ERR(ret_fr, is_fpd_set, s, source_id, addr, is_write) {\
    if (ret_fr) {                                                             \
        ret_fr = -ret_fr;                                                     \
        if (is_fpd_set && vtd_is_qualified_fault(ret_fr)) {                   \
            trace_vtd_fault_disabled();                                       \
        } else {                                                              \
            vtd_report_dmar_fault(s, source_id, addr, ret_fr, is_write);      \
        }                                                                     \
        goto error;                                                           \
    }                                                                         \
}

static void vtd_address_space_refresh_all(IntelIOMMUState *s);
static void vtd_address_space_unmap(VTDAddressSpace *as, IOMMUNotifier *n);

static void vtd_panic_require_caching_mode(void)
{
    error_report("We need to set caching-mode=on for intel-iommu to enable "
                 "device assignment with IOMMU protection.");
    exit(1);
}

static void vtd_define_quad(IntelIOMMUState *s, hwaddr addr, uint64_t val,
                            uint64_t wmask, uint64_t w1cmask)
{
    stq_le_p(&s->csr[addr], val);
    stq_le_p(&s->wmask[addr], wmask);
    stq_le_p(&s->w1cmask[addr], w1cmask);
}

static void vtd_define_quad_wo(IntelIOMMUState *s, hwaddr addr, uint64_t mask)
{
    stq_le_p(&s->womask[addr], mask);
}

static void vtd_define_long(IntelIOMMUState *s, hwaddr addr, uint32_t val,
                            uint32_t wmask, uint32_t w1cmask)
{
    stl_le_p(&s->csr[addr], val);
    stl_le_p(&s->wmask[addr], wmask);
    stl_le_p(&s->w1cmask[addr], w1cmask);
}

static void vtd_define_long_wo(IntelIOMMUState *s, hwaddr addr, uint32_t mask)
{
    stl_le_p(&s->womask[addr], mask);
}

/* "External" get/set operations */
static void vtd_set_quad(IntelIOMMUState *s, hwaddr addr, uint64_t val)
{
    uint64_t oldval = ldq_le_p(&s->csr[addr]);
    uint64_t wmask = ldq_le_p(&s->wmask[addr]);
    uint64_t w1cmask = ldq_le_p(&s->w1cmask[addr]);
    stq_le_p(&s->csr[addr],
             ((oldval & ~wmask) | (val & wmask)) & ~(w1cmask & val));
}

static void vtd_set_long(IntelIOMMUState *s, hwaddr addr, uint32_t val)
{
    uint32_t oldval = ldl_le_p(&s->csr[addr]);
    uint32_t wmask = ldl_le_p(&s->wmask[addr]);
    uint32_t w1cmask = ldl_le_p(&s->w1cmask[addr]);
    stl_le_p(&s->csr[addr],
             ((oldval & ~wmask) | (val & wmask)) & ~(w1cmask & val));
}

static uint64_t vtd_get_quad(IntelIOMMUState *s, hwaddr addr)
{
    uint64_t val = ldq_le_p(&s->csr[addr]);
    uint64_t womask = ldq_le_p(&s->womask[addr]);
    return val & ~womask;
}

static uint32_t vtd_get_long(IntelIOMMUState *s, hwaddr addr)
{
    uint32_t val = ldl_le_p(&s->csr[addr]);
    uint32_t womask = ldl_le_p(&s->womask[addr]);
    return val & ~womask;
}

/* "Internal" get/set operations */
static uint64_t vtd_get_quad_raw(IntelIOMMUState *s, hwaddr addr)
{
    return ldq_le_p(&s->csr[addr]);
}

static uint32_t vtd_get_long_raw(IntelIOMMUState *s, hwaddr addr)
{
    return ldl_le_p(&s->csr[addr]);
}

static void vtd_set_quad_raw(IntelIOMMUState *s, hwaddr addr, uint64_t val)
{
    stq_le_p(&s->csr[addr], val);
}

static uint32_t vtd_set_clear_mask_long(IntelIOMMUState *s, hwaddr addr,
                                        uint32_t clear, uint32_t mask)
{
    uint32_t new_val = (ldl_le_p(&s->csr[addr]) & ~clear) | mask;
    stl_le_p(&s->csr[addr], new_val);
    return new_val;
}

static uint64_t vtd_set_clear_mask_quad(IntelIOMMUState *s, hwaddr addr,
                                        uint64_t clear, uint64_t mask)
{
    uint64_t new_val = (ldq_le_p(&s->csr[addr]) & ~clear) | mask;
    stq_le_p(&s->csr[addr], new_val);
    return new_val;
}

static inline void vtd_iommu_lock(IntelIOMMUState *s)
{
    qemu_mutex_lock(&s->iommu_lock);
}

static inline void vtd_iommu_unlock(IntelIOMMUState *s)
{
    qemu_mutex_unlock(&s->iommu_lock);
}

static void vtd_update_scalable_state(IntelIOMMUState *s)
{
    uint64_t val = vtd_get_quad_raw(s, DMAR_RTADDR_REG);

    if (s->scalable_mode) {
        s->root_scalable = val & VTD_RTADDR_SMT;
    }
}

/* Whether the address space needs to notify new mappings */
static inline gboolean vtd_as_has_map_notifier(VTDAddressSpace *as)
{
    return as->notifier_flags & IOMMU_NOTIFIER_MAP;
}

/* GHashTable functions */
static gboolean vtd_uint64_equal(gconstpointer v1, gconstpointer v2)
{
    return *((const uint64_t *)v1) == *((const uint64_t *)v2);
}

static guint vtd_uint64_hash(gconstpointer v)
{
    return (guint)*(const uint64_t *)v;
}

static gboolean vtd_hash_remove_by_domain(gpointer key, gpointer value,
                                          gpointer user_data)
{
    VTDIOTLBEntry *entry = (VTDIOTLBEntry *)value;
    uint16_t domain_id = *(uint16_t *)user_data;
    return entry->domain_id == domain_id;
}

/* The shift of an addr for a certain level of paging structure */
static inline uint32_t vtd_slpt_level_shift(uint32_t level)
{
    assert(level != 0);
    return VTD_PAGE_SHIFT_4K + (level - 1) * VTD_SL_LEVEL_BITS;
}

static inline uint64_t vtd_slpt_level_page_mask(uint32_t level)
{
    return ~((1ULL << vtd_slpt_level_shift(level)) - 1);
}

static gboolean vtd_hash_remove_by_page(gpointer key, gpointer value,
                                        gpointer user_data)
{
    VTDIOTLBEntry *entry = (VTDIOTLBEntry *)value;
    VTDIOTLBPageInvInfo *info = (VTDIOTLBPageInvInfo *)user_data;
    uint64_t gfn = (info->addr >> VTD_PAGE_SHIFT_4K) & info->mask;
    uint64_t gfn_tlb = (info->addr & entry->mask) >> VTD_PAGE_SHIFT_4K;
    return (entry->domain_id == info->domain_id) &&
            (((entry->gfn & info->mask) == gfn) ||
             (entry->gfn == gfn_tlb));
}

/* Reset all the gen of VTDAddressSpace to zero and set the gen of
 * IntelIOMMUState to 1.  Must be called with IOMMU lock held.
 */
static void vtd_reset_context_cache_locked(IntelIOMMUState *s)
{
    VTDAddressSpace *vtd_as;
    VTDBus *vtd_bus;
    GHashTableIter bus_it;
    uint32_t devfn_it;

    trace_vtd_context_cache_reset();

    g_hash_table_iter_init(&bus_it, s->vtd_as_by_busptr);

    while (g_hash_table_iter_next (&bus_it, NULL, (void**)&vtd_bus)) {
        for (devfn_it = 0; devfn_it < PCI_DEVFN_MAX; ++devfn_it) {
            vtd_as = vtd_bus->dev_as[devfn_it];
            if (!vtd_as) {
                continue;
            }
            vtd_as->context_cache_entry.context_cache_gen = 0;
        }
    }
    s->context_cache_gen = 1;
}

/* Must be called with IOMMU lock held. */
static void vtd_reset_iotlb_locked(IntelIOMMUState *s)
{
    assert(s->iotlb);
    g_hash_table_remove_all(s->iotlb);
}

static void vtd_reset_iotlb(IntelIOMMUState *s)
{
    vtd_iommu_lock(s);
    vtd_reset_iotlb_locked(s);
    vtd_iommu_unlock(s);
}

static void vtd_reset_caches(IntelIOMMUState *s)
{
    vtd_iommu_lock(s);
    vtd_reset_iotlb_locked(s);
    vtd_reset_context_cache_locked(s);
    vtd_iommu_unlock(s);
}

static uint64_t vtd_get_iotlb_key(uint64_t gfn, uint16_t source_id,
                                  uint32_t level)
{
    return gfn | ((uint64_t)(source_id) << VTD_IOTLB_SID_SHIFT) |
           ((uint64_t)(level) << VTD_IOTLB_LVL_SHIFT);
}

static uint64_t vtd_get_iotlb_gfn(hwaddr addr, uint32_t level)
{
    return (addr & vtd_slpt_level_page_mask(level)) >> VTD_PAGE_SHIFT_4K;
}

/* Must be called with IOMMU lock held */
static VTDIOTLBEntry *vtd_lookup_iotlb(IntelIOMMUState *s, uint16_t source_id,
                                       hwaddr addr)
{
    VTDIOTLBEntry *entry;
    uint64_t key;
    int level;

    for (level = VTD_SL_PT_LEVEL; level < VTD_SL_PML4_LEVEL; level++) {
        key = vtd_get_iotlb_key(vtd_get_iotlb_gfn(addr, level),
                                source_id, level);
        entry = g_hash_table_lookup(s->iotlb, &key);
        if (entry) {
            goto out;
        }
    }

out:
    return entry;
}

/* Must be with IOMMU lock held */
static void vtd_update_iotlb(IntelIOMMUState *s, uint16_t source_id,
                             uint16_t domain_id, hwaddr addr, uint64_t slpte,
                             uint8_t access_flags, uint32_t level)
{
    VTDIOTLBEntry *entry = g_malloc(sizeof(*entry));
    uint64_t *key = g_malloc(sizeof(*key));
    uint64_t gfn = vtd_get_iotlb_gfn(addr, level);

    trace_vtd_iotlb_page_update(source_id, addr, slpte, domain_id);
    if (g_hash_table_size(s->iotlb) >= VTD_IOTLB_MAX_SIZE) {
        trace_vtd_iotlb_reset("iotlb exceeds size limit");
        vtd_reset_iotlb_locked(s);
    }

    entry->gfn = gfn;
    entry->domain_id = domain_id;
    entry->slpte = slpte;
    entry->access_flags = access_flags;
    entry->mask = vtd_slpt_level_page_mask(level);
    *key = vtd_get_iotlb_key(gfn, source_id, level);
    g_hash_table_replace(s->iotlb, key, entry);
}

/* Given the reg addr of both the message data and address, generate an
 * interrupt via MSI.
 */
static void vtd_generate_interrupt(IntelIOMMUState *s, hwaddr mesg_addr_reg,
                                   hwaddr mesg_data_reg)
{
    MSIMessage msi;

    assert(mesg_data_reg < DMAR_REG_SIZE);
    assert(mesg_addr_reg < DMAR_REG_SIZE);

    msi.address = vtd_get_long_raw(s, mesg_addr_reg);
    msi.data = vtd_get_long_raw(s, mesg_data_reg);

    trace_vtd_irq_generate(msi.address, msi.data);

    apic_get_class()->send_msi(&msi);
}

/* Generate a fault event to software via MSI if conditions are met.
 * Notice that the value of FSTS_REG being passed to it should be the one
 * before any update.
 */
static void vtd_generate_fault_event(IntelIOMMUState *s, uint32_t pre_fsts)
{
    if (pre_fsts & VTD_FSTS_PPF || pre_fsts & VTD_FSTS_PFO ||
        pre_fsts & VTD_FSTS_IQE) {
        error_report_once("There are previous interrupt conditions "
                          "to be serviced by software, fault event "
                          "is not generated");
        return;
    }
    vtd_set_clear_mask_long(s, DMAR_FECTL_REG, 0, VTD_FECTL_IP);
    if (vtd_get_long_raw(s, DMAR_FECTL_REG) & VTD_FECTL_IM) {
        error_report_once("Interrupt Mask set, irq is not generated");
    } else {
        vtd_generate_interrupt(s, DMAR_FEADDR_REG, DMAR_FEDATA_REG);
        vtd_set_clear_mask_long(s, DMAR_FECTL_REG, VTD_FECTL_IP, 0);
    }
}

/* Check if the Fault (F) field of the Fault Recording Register referenced by
 * @index is Set.
 */
static bool vtd_is_frcd_set(IntelIOMMUState *s, uint16_t index)
{
    /* Each reg is 128-bit */
    hwaddr addr = DMAR_FRCD_REG_OFFSET + (((uint64_t)index) << 4);
    addr += 8; /* Access the high 64-bit half */

    assert(index < DMAR_FRCD_REG_NR);

    return vtd_get_quad_raw(s, addr) & VTD_FRCD_F;
}

/* Update the PPF field of Fault Status Register.
 * Should be called whenever change the F field of any fault recording
 * registers.
 */
static void vtd_update_fsts_ppf(IntelIOMMUState *s)
{
    uint32_t i;
    uint32_t ppf_mask = 0;

    for (i = 0; i < DMAR_FRCD_REG_NR; i++) {
        if (vtd_is_frcd_set(s, i)) {
            ppf_mask = VTD_FSTS_PPF;
            break;
        }
    }
    vtd_set_clear_mask_long(s, DMAR_FSTS_REG, VTD_FSTS_PPF, ppf_mask);
    trace_vtd_fsts_ppf(!!ppf_mask);
}

static void vtd_set_frcd_and_update_ppf(IntelIOMMUState *s, uint16_t index)
{
    /* Each reg is 128-bit */
    hwaddr addr = DMAR_FRCD_REG_OFFSET + (((uint64_t)index) << 4);
    addr += 8; /* Access the high 64-bit half */

    assert(index < DMAR_FRCD_REG_NR);

    vtd_set_clear_mask_quad(s, addr, 0, VTD_FRCD_F);
    vtd_update_fsts_ppf(s);
}

/* Must not update F field now, should be done later */
static void vtd_record_frcd(IntelIOMMUState *s, uint16_t index,
                            uint16_t source_id, hwaddr addr,
                            VTDFaultReason fault, bool is_write)
{
    uint64_t hi = 0, lo;
    hwaddr frcd_reg_addr = DMAR_FRCD_REG_OFFSET + (((uint64_t)index) << 4);

    assert(index < DMAR_FRCD_REG_NR);

    lo = VTD_FRCD_FI(addr);
    hi = VTD_FRCD_SID(source_id) | VTD_FRCD_FR(fault);
    if (!is_write) {
        hi |= VTD_FRCD_T;
    }
    vtd_set_quad_raw(s, frcd_reg_addr, lo);
    vtd_set_quad_raw(s, frcd_reg_addr + 8, hi);

    trace_vtd_frr_new(index, hi, lo);
}

/* Try to collapse multiple pending faults from the same requester */
static bool vtd_try_collapse_fault(IntelIOMMUState *s, uint16_t source_id)
{
    uint32_t i;
    uint64_t frcd_reg;
    hwaddr addr = DMAR_FRCD_REG_OFFSET + 8; /* The high 64-bit half */

    for (i = 0; i < DMAR_FRCD_REG_NR; i++) {
        frcd_reg = vtd_get_quad_raw(s, addr);
        if ((frcd_reg & VTD_FRCD_F) &&
            ((frcd_reg & VTD_FRCD_SID_MASK) == source_id)) {
            return true;
        }
        addr += 16; /* 128-bit for each */
    }
    return false;
}

/* Log and report an DMAR (address translation) fault to software */
static void vtd_report_dmar_fault(IntelIOMMUState *s, uint16_t source_id,
                                  hwaddr addr, VTDFaultReason fault,
                                  bool is_write)
{
    uint32_t fsts_reg = vtd_get_long_raw(s, DMAR_FSTS_REG);

    assert(fault < VTD_FR_MAX);

    if (fault == VTD_FR_RESERVED_ERR) {
        /* This is not a normal fault reason case. Drop it. */
        return;
    }

    trace_vtd_dmar_fault(source_id, fault, addr, is_write);

    if (fsts_reg & VTD_FSTS_PFO) {
        error_report_once("New fault is not recorded due to "
                          "Primary Fault Overflow");
        return;
    }

    if (vtd_try_collapse_fault(s, source_id)) {
        error_report_once("New fault is not recorded due to "
                          "compression of faults");
        return;
    }

    if (vtd_is_frcd_set(s, s->next_frcd_reg)) {
        error_report_once("Next Fault Recording Reg is used, "
                          "new fault is not recorded, set PFO field");
        vtd_set_clear_mask_long(s, DMAR_FSTS_REG, 0, VTD_FSTS_PFO);
        return;
    }

    vtd_record_frcd(s, s->next_frcd_reg, source_id, addr, fault, is_write);

    if (fsts_reg & VTD_FSTS_PPF) {
        error_report_once("There are pending faults already, "
                          "fault event is not generated");
        vtd_set_frcd_and_update_ppf(s, s->next_frcd_reg);
        s->next_frcd_reg++;
        if (s->next_frcd_reg == DMAR_FRCD_REG_NR) {
            s->next_frcd_reg = 0;
        }
    } else {
        vtd_set_clear_mask_long(s, DMAR_FSTS_REG, VTD_FSTS_FRI_MASK,
                                VTD_FSTS_FRI(s->next_frcd_reg));
        vtd_set_frcd_and_update_ppf(s, s->next_frcd_reg); /* Will set PPF */
        s->next_frcd_reg++;
        if (s->next_frcd_reg == DMAR_FRCD_REG_NR) {
            s->next_frcd_reg = 0;
        }
        /* This case actually cause the PPF to be Set.
         * So generate fault event (interrupt).
         */
         vtd_generate_fault_event(s, fsts_reg);
    }
}

/* Handle Invalidation Queue Errors of queued invalidation interface error
 * conditions.
 */
static void vtd_handle_inv_queue_error(IntelIOMMUState *s)
{
    uint32_t fsts_reg = vtd_get_long_raw(s, DMAR_FSTS_REG);

    vtd_set_clear_mask_long(s, DMAR_FSTS_REG, 0, VTD_FSTS_IQE);
    vtd_generate_fault_event(s, fsts_reg);
}

/* Set the IWC field and try to generate an invalidation completion interrupt */
static void vtd_generate_completion_event(IntelIOMMUState *s)
{
    if (vtd_get_long_raw(s, DMAR_ICS_REG) & VTD_ICS_IWC) {
        trace_vtd_inv_desc_wait_irq("One pending, skip current");
        return;
    }
    vtd_set_clear_mask_long(s, DMAR_ICS_REG, 0, VTD_ICS_IWC);
    vtd_set_clear_mask_long(s, DMAR_IECTL_REG, 0, VTD_IECTL_IP);
    if (vtd_get_long_raw(s, DMAR_IECTL_REG) & VTD_IECTL_IM) {
        trace_vtd_inv_desc_wait_irq("IM in IECTL_REG is set, "
                                    "new event not generated");
        return;
    } else {
        /* Generate the interrupt event */
        trace_vtd_inv_desc_wait_irq("Generating complete event");
        vtd_generate_interrupt(s, DMAR_IEADDR_REG, DMAR_IEDATA_REG);
        vtd_set_clear_mask_long(s, DMAR_IECTL_REG, VTD_IECTL_IP, 0);
    }
}

static inline bool vtd_root_entry_present(IntelIOMMUState *s,
                                          VTDRootEntry *re,
                                          uint8_t devfn)
{
    if (s->root_scalable && devfn > UINT8_MAX / 2) {
        return re->hi & VTD_ROOT_ENTRY_P;
    }

    return re->lo & VTD_ROOT_ENTRY_P;
}

static int vtd_get_root_entry(IntelIOMMUState *s, uint8_t index,
                              VTDRootEntry *re)
{
    dma_addr_t addr;

    addr = s->root + index * sizeof(*re);
    if (dma_memory_read(&address_space_memory, addr, re, sizeof(*re))) {
        re->lo = 0;
        return -VTD_FR_ROOT_TABLE_INV;
    }
    re->lo = le64_to_cpu(re->lo);
    re->hi = le64_to_cpu(re->hi);
    return 0;
}

static inline bool vtd_ce_present(VTDContextEntry *context)
{
    return context->lo & VTD_CONTEXT_ENTRY_P;
}

static int vtd_get_context_entry_from_root(IntelIOMMUState *s,
                                           VTDRootEntry *re,
                                           uint8_t index,
                                           VTDContextEntry *ce)
{
    dma_addr_t addr, ce_size;

    /* we have checked that root entry is present */
    ce_size = s->root_scalable ? VTD_CTX_ENTRY_SCALABLE_SIZE :
              VTD_CTX_ENTRY_LEGACY_SIZE;

    if (s->root_scalable && index > UINT8_MAX / 2) {
        index = index & (~VTD_DEVFN_CHECK_MASK);
        addr = re->hi & VTD_ROOT_ENTRY_CTP;
    } else {
        addr = re->lo & VTD_ROOT_ENTRY_CTP;
    }

    addr = addr + index * ce_size;
    if (dma_memory_read(&address_space_memory, addr, ce, ce_size)) {
        return -VTD_FR_CONTEXT_TABLE_INV;
    }

    ce->lo = le64_to_cpu(ce->lo);
    ce->hi = le64_to_cpu(ce->hi);
    if (ce_size == VTD_CTX_ENTRY_SCALABLE_SIZE) {
        ce->val[2] = le64_to_cpu(ce->val[2]);
        ce->val[3] = le64_to_cpu(ce->val[3]);
    }
    return 0;
}

static inline dma_addr_t vtd_ce_get_slpt_base(VTDContextEntry *ce)
{
    return ce->lo & VTD_CONTEXT_ENTRY_SLPTPTR;
}

static inline uint64_t vtd_get_slpte_addr(uint64_t slpte, uint8_t aw)
{
    return slpte & VTD_SL_PT_BASE_ADDR_MASK(aw);
}

/* Whether the pte indicates the address of the page frame */
static inline bool vtd_is_last_slpte(uint64_t slpte, uint32_t level)
{
    return level == VTD_SL_PT_LEVEL || (slpte & VTD_SL_PT_PAGE_SIZE_MASK);
}

/* Get the content of a spte located in @base_addr[@index] */
static uint64_t vtd_get_slpte(dma_addr_t base_addr, uint32_t index)
{
    uint64_t slpte;

    assert(index < VTD_SL_PT_ENTRY_NR);

    if (dma_memory_read(&address_space_memory,
                        base_addr + index * sizeof(slpte), &slpte,
                        sizeof(slpte))) {
        slpte = (uint64_t)-1;
        return slpte;
    }
    slpte = le64_to_cpu(slpte);
    return slpte;
}

/* Given an iova and the level of paging structure, return the offset
 * of current level.
 */
static inline uint32_t vtd_iova_level_offset(uint64_t iova, uint32_t level)
{
    return (iova >> vtd_slpt_level_shift(level)) &
            ((1ULL << VTD_SL_LEVEL_BITS) - 1);
}

/* Check Capability Register to see if the @level of page-table is supported */
static inline bool vtd_is_level_supported(IntelIOMMUState *s, uint32_t level)
{
    return VTD_CAP_SAGAW_MASK & s->cap &
           (1ULL << (level - 2 + VTD_CAP_SAGAW_SHIFT));
}

/* Return true if check passed, otherwise false */
static inline bool vtd_pe_type_check(X86IOMMUState *x86_iommu,
                                     VTDPASIDEntry *pe)
{
    switch (VTD_PE_GET_TYPE(pe)) {
    case VTD_SM_PASID_ENTRY_FLT:
    case VTD_SM_PASID_ENTRY_SLT:
    case VTD_SM_PASID_ENTRY_NESTED:
        break;
    case VTD_SM_PASID_ENTRY_PT:
        if (!x86_iommu->pt_supported) {
            return false;
        }
        break;
    default:
        /* Unknwon type */
        return false;
    }
    return true;
}

static int vtd_get_pasid_dire(dma_addr_t pasid_dir_base,
                              uint32_t pasid,
                              VTDPASIDDirEntry *pdire)
{
    uint32_t index;
    dma_addr_t addr, entry_size;

    index = VTD_PASID_DIR_INDEX(pasid);
    entry_size = VTD_PASID_DIR_ENTRY_SIZE;
    addr = pasid_dir_base + index * entry_size;
    if (dma_memory_read(&address_space_memory, addr, pdire, entry_size)) {
        return -VTD_FR_PASID_TABLE_INV;
    }

    return 0;
}

static int vtd_get_pasid_entry(IntelIOMMUState *s,
                               uint32_t pasid,
                               VTDPASIDDirEntry *pdire,
                               VTDPASIDEntry *pe)
{
    uint32_t index;
    dma_addr_t addr, entry_size;
    X86IOMMUState *x86_iommu = X86_IOMMU_DEVICE(s);

    index = VTD_PASID_TABLE_INDEX(pasid);
    entry_size = VTD_PASID_ENTRY_SIZE;
    addr = pdire->val & VTD_PASID_TABLE_BASE_ADDR_MASK;
    addr = addr + index * entry_size;
    if (dma_memory_read(&address_space_memory, addr, pe, entry_size)) {
        return -VTD_FR_PASID_TABLE_INV;
    }

    /* Do translation type check */
    if (!vtd_pe_type_check(x86_iommu, pe)) {
        return -VTD_FR_PASID_TABLE_INV;
    }

    if (!vtd_is_level_supported(s, VTD_PE_GET_LEVEL(pe))) {
        return -VTD_FR_PASID_TABLE_INV;
    }

    return 0;
}

static int vtd_get_pasid_entry_from_pasid(IntelIOMMUState *s,
                                          dma_addr_t pasid_dir_base,
                                          uint32_t pasid,
                                          VTDPASIDEntry *pe)
{
    int ret;
    VTDPASIDDirEntry pdire;

    ret = vtd_get_pasid_dire(pasid_dir_base, pasid, &pdire);
    if (ret) {
        return ret;
    }

    ret = vtd_get_pasid_entry(s, pasid, &pdire, pe);
    if (ret) {
        return ret;
    }

    return ret;
}

static int vtd_ce_get_rid2pasid_entry(IntelIOMMUState *s,
                                      VTDContextEntry *ce,
                                      VTDPASIDEntry *pe)
{
    uint32_t pasid;
    dma_addr_t pasid_dir_base;
    int ret = 0;

    pasid = VTD_CE_GET_RID2PASID(ce);
    pasid_dir_base = VTD_CE_GET_PASID_DIR_TABLE(ce);
    ret = vtd_get_pasid_entry_from_pasid(s, pasid_dir_base, pasid, pe);

    return ret;
}

static int vtd_ce_get_pasid_fpd(IntelIOMMUState *s,
                                VTDContextEntry *ce,
                                bool *pe_fpd_set)
{
    int ret;
    uint32_t pasid;
    dma_addr_t pasid_dir_base;
    VTDPASIDDirEntry pdire;
    VTDPASIDEntry pe;

    pasid = VTD_CE_GET_RID2PASID(ce);
    pasid_dir_base = VTD_CE_GET_PASID_DIR_TABLE(ce);

    ret = vtd_get_pasid_dire(pasid_dir_base, pasid, &pdire);
    if (ret) {
        return ret;
    }

    if (pdire.val & VTD_PASID_DIR_FPD) {
        *pe_fpd_set = true;
        return 0;
    }

    ret = vtd_get_pasid_entry(s, pasid, &pdire, &pe);
    if (ret) {
        return ret;
    }

    if (pe.val[0] & VTD_PASID_ENTRY_FPD) {
        *pe_fpd_set = true;
    }

    return 0;
}

/* Get the page-table level that hardware should use for the second-level
 * page-table walk from the Address Width field of context-entry.
 */
static inline uint32_t vtd_ce_get_level(VTDContextEntry *ce)
{
    return 2 + (ce->hi & VTD_CONTEXT_ENTRY_AW);
}

static uint32_t vtd_get_iova_level(IntelIOMMUState *s,
                                   VTDContextEntry *ce)
{
    VTDPASIDEntry pe;

    if (s->root_scalable) {
        vtd_ce_get_rid2pasid_entry(s, ce, &pe);
        return VTD_PE_GET_LEVEL(&pe);
    }

    return vtd_ce_get_level(ce);
}

static inline uint32_t vtd_ce_get_agaw(VTDContextEntry *ce)
{
    return 30 + (ce->hi & VTD_CONTEXT_ENTRY_AW) * 9;
}

static uint32_t vtd_get_iova_agaw(IntelIOMMUState *s,
                                  VTDContextEntry *ce)
{
    VTDPASIDEntry pe;

    if (s->root_scalable) {
        vtd_ce_get_rid2pasid_entry(s, ce, &pe);
        return 30 + ((pe.val[0] >> 2) & VTD_SM_PASID_ENTRY_AW) * 9;
    }

    return vtd_ce_get_agaw(ce);
}

static inline uint32_t vtd_ce_get_type(VTDContextEntry *ce)
{
    return ce->lo & VTD_CONTEXT_ENTRY_TT;
}

/* Only for Legacy Mode. Return true if check passed, otherwise false */
static inline bool vtd_ce_type_check(X86IOMMUState *x86_iommu,
                                     VTDContextEntry *ce)
{
    switch (vtd_ce_get_type(ce)) {
    case VTD_CONTEXT_TT_MULTI_LEVEL:
        /* Always supported */
        break;
    case VTD_CONTEXT_TT_DEV_IOTLB:
        if (!x86_iommu->dt_supported) {
            error_report_once("%s: DT specified but not supported", __func__);
            return false;
        }
        break;
    case VTD_CONTEXT_TT_PASS_THROUGH:
        if (!x86_iommu->pt_supported) {
            error_report_once("%s: PT specified but not supported", __func__);
            return false;
        }
        break;
    default:
        /* Unknown type */
        error_report_once("%s: unknown ce type: %"PRIu32, __func__,
                          vtd_ce_get_type(ce));
        return false;
    }
    return true;
}

static inline uint64_t vtd_iova_limit(IntelIOMMUState *s,
                                      VTDContextEntry *ce, uint8_t aw)
{
    uint32_t ce_agaw = vtd_get_iova_agaw(s, ce);
    return 1ULL << MIN(ce_agaw, aw);
}

/* Return true if IOVA passes range check, otherwise false. */
static inline bool vtd_iova_range_check(IntelIOMMUState *s,
                                        uint64_t iova, VTDContextEntry *ce,
                                        uint8_t aw)
{
    /*
     * Check if @iova is above 2^X-1, where X is the minimum of MGAW
     * in CAP_REG and AW in context-entry.
     */
    return !(iova & ~(vtd_iova_limit(s, ce, aw) - 1));
}

static dma_addr_t vtd_get_iova_pgtbl_base(IntelIOMMUState *s,
                                          VTDContextEntry *ce)
{
    VTDPASIDEntry pe;

    if (s->root_scalable) {
        vtd_ce_get_rid2pasid_entry(s, ce, &pe);
        return pe.val[0] & VTD_SM_PASID_ENTRY_SLPTPTR;
    }

    return vtd_ce_get_slpt_base(ce);
}

/*
 * Rsvd field masks for spte:
 *     Index [1] to [4] 4k pages
 *     Index [5] to [8] large pages
 */
static uint64_t vtd_paging_entry_rsvd_field[9];

static bool vtd_slpte_nonzero_rsvd(uint64_t slpte, uint32_t level)
{
    if (slpte & VTD_SL_PT_PAGE_SIZE_MASK) {
        /* Maybe large page */
        return slpte & vtd_paging_entry_rsvd_field[level + 4];
    } else {
        return slpte & vtd_paging_entry_rsvd_field[level];
    }
}

/* Find the VTD address space associated with a given bus number */
static VTDBus *vtd_find_as_from_bus_num(IntelIOMMUState *s, uint8_t bus_num)
{
    VTDBus *vtd_bus = s->vtd_as_by_bus_num[bus_num];
    if (!vtd_bus) {
        /*
         * Iterate over the registered buses to find the one which
         * currently hold this bus number, and update the bus_num
         * lookup table:
         */
        GHashTableIter iter;

        g_hash_table_iter_init(&iter, s->vtd_as_by_busptr);
        while (g_hash_table_iter_next(&iter, NULL, (void **)&vtd_bus)) {
            if (pci_bus_num(vtd_bus->bus) == bus_num) {
                s->vtd_as_by_bus_num[bus_num] = vtd_bus;
                return vtd_bus;
            }
        }
    }
    return vtd_bus;
}

/* Given the @iova, get relevant @slptep. @slpte_level will be the last level
 * of the translation, can be used for deciding the size of large page.
 */
static int vtd_iova_to_slpte(IntelIOMMUState *s, VTDContextEntry *ce,
                             uint64_t iova, bool is_write,
                             uint64_t *slptep, uint32_t *slpte_level,
                             bool *reads, bool *writes, uint8_t aw_bits)
{
    dma_addr_t addr = vtd_get_iova_pgtbl_base(s, ce);
    uint32_t level = vtd_get_iova_level(s, ce);
    uint32_t offset;
    uint64_t slpte;
    uint64_t access_right_check;

    if (!vtd_iova_range_check(s, iova, ce, aw_bits)) {
        error_report_once("%s: detected IOVA overflow (iova=0x%" PRIx64 ")",
                          __func__, iova);
        return -VTD_FR_ADDR_BEYOND_MGAW;
    }

    /* FIXME: what is the Atomics request here? */
    access_right_check = is_write ? VTD_SL_W : VTD_SL_R;

    while (true) {
        offset = vtd_iova_level_offset(iova, level);
        slpte = vtd_get_slpte(addr, offset);

        if (slpte == (uint64_t)-1) {
            error_report_once("%s: detected read error on DMAR slpte "
                              "(iova=0x%" PRIx64 ")", __func__, iova);
            if (level == vtd_get_iova_level(s, ce)) {
                /* Invalid programming of context-entry */
                return -VTD_FR_CONTEXT_ENTRY_INV;
            } else {
                return -VTD_FR_PAGING_ENTRY_INV;
            }
        }
        *reads = (*reads) && (slpte & VTD_SL_R);
        *writes = (*writes) && (slpte & VTD_SL_W);
        if (!(slpte & access_right_check)) {
            error_report_once("%s: detected slpte permission error "
                              "(iova=0x%" PRIx64 ", level=0x%" PRIx32 ", "
                              "slpte=0x%" PRIx64 ", write=%d)", __func__,
                              iova, level, slpte, is_write);
            return is_write ? -VTD_FR_WRITE : -VTD_FR_READ;
        }
        if (vtd_slpte_nonzero_rsvd(slpte, level)) {
            error_report_once("%s: detected splte reserve non-zero "
                              "iova=0x%" PRIx64 ", level=0x%" PRIx32
                              "slpte=0x%" PRIx64 ")", __func__, iova,
                              level, slpte);
            return -VTD_FR_PAGING_ENTRY_RSVD;
        }

        if (vtd_is_last_slpte(slpte, level)) {
            *slptep = slpte;
            *slpte_level = level;
            return 0;
        }
        addr = vtd_get_slpte_addr(slpte, aw_bits);
        level--;
    }
}

typedef int (*vtd_page_walk_hook)(IOMMUTLBEntry *entry, void *private);

/**
 * Constant information used during page walking
 *
 * @hook_fn: hook func to be called when detected page
 * @private: private data to be passed into hook func
 * @notify_unmap: whether we should notify invalid entries
 * @as: VT-d address space of the device
 * @aw: maximum address width
 * @domain: domain ID of the page walk
 */
typedef struct {
    VTDAddressSpace *as;
    vtd_page_walk_hook hook_fn;
    void *private;
    bool notify_unmap;
    uint8_t aw;
    uint16_t domain_id;
} vtd_page_walk_info;

static int vtd_page_walk_one(IOMMUTLBEntry *entry, vtd_page_walk_info *info)
{
    VTDAddressSpace *as = info->as;
    vtd_page_walk_hook hook_fn = info->hook_fn;
    void *private = info->private;
    DMAMap target = {
        .iova = entry->iova,
        .size = entry->addr_mask,
        .translated_addr = entry->translated_addr,
        .perm = entry->perm,
    };
    DMAMap *mapped = iova_tree_find(as->iova_tree, &target);

    if (entry->perm == IOMMU_NONE && !info->notify_unmap) {
        trace_vtd_page_walk_one_skip_unmap(entry->iova, entry->addr_mask);
        return 0;
    }

    assert(hook_fn);

    /* Update local IOVA mapped ranges */
    if (entry->perm) {
        if (mapped) {
            /* If it's exactly the same translation, skip */
            if (!memcmp(mapped, &target, sizeof(target))) {
                trace_vtd_page_walk_one_skip_map(entry->iova, entry->addr_mask,
                                                 entry->translated_addr);
                return 0;
            } else {
                /*
                 * Translation changed.  Normally this should not
                 * happen, but it can happen when with buggy guest
                 * OSes.  Note that there will be a small window that
                 * we don't have map at all.  But that's the best
                 * effort we can do.  The ideal way to emulate this is
                 * atomically modify the PTE to follow what has
                 * changed, but we can't.  One example is that vfio
                 * driver only has VFIO_IOMMU_[UN]MAP_DMA but no
                 * interface to modify a mapping (meanwhile it seems
                 * meaningless to even provide one).  Anyway, let's
                 * mark this as a TODO in case one day we'll have
                 * a better solution.
                 */
                IOMMUAccessFlags cache_perm = entry->perm;
                int ret;

                /* Emulate an UNMAP */
                entry->perm = IOMMU_NONE;
                trace_vtd_page_walk_one(info->domain_id,
                                        entry->iova,
                                        entry->translated_addr,
                                        entry->addr_mask,
                                        entry->perm);
                ret = hook_fn(entry, private);
                if (ret) {
                    return ret;
                }
                /* Drop any existing mapping */
                iova_tree_remove(as->iova_tree, &target);
                /* Recover the correct permission */
                entry->perm = cache_perm;
            }
        }
        iova_tree_insert(as->iova_tree, &target);
    } else {
        if (!mapped) {
            /* Skip since we didn't map this range at all */
            trace_vtd_page_walk_one_skip_unmap(entry->iova, entry->addr_mask);
            return 0;
        }
        iova_tree_remove(as->iova_tree, &target);
    }

    trace_vtd_page_walk_one(info->domain_id, entry->iova,
                            entry->translated_addr, entry->addr_mask,
                            entry->perm);
    return hook_fn(entry, private);
}

/**
 * vtd_page_walk_level - walk over specific level for IOVA range
 *
 * @addr: base GPA addr to start the walk
 * @start: IOVA range start address
 * @end: IOVA range end address (start <= addr < end)
 * @read: whether parent level has read permission
 * @write: whether parent level has write permission
 * @info: constant information for the page walk
 */
static int vtd_page_walk_level(dma_addr_t addr, uint64_t start,
                               uint64_t end, uint32_t level, bool read,
                               bool write, vtd_page_walk_info *info)
{
    bool read_cur, write_cur, entry_valid;
    uint32_t offset;
    uint64_t slpte;
    uint64_t subpage_size, subpage_mask;
    IOMMUTLBEntry entry;
    uint64_t iova = start;
    uint64_t iova_next;
    int ret = 0;

    trace_vtd_page_walk_level(addr, level, start, end);

    subpage_size = 1ULL << vtd_slpt_level_shift(level);
    subpage_mask = vtd_slpt_level_page_mask(level);

    while (iova < end) {
        iova_next = (iova & subpage_mask) + subpage_size;

        offset = vtd_iova_level_offset(iova, level);
        slpte = vtd_get_slpte(addr, offset);

        if (slpte == (uint64_t)-1) {
            trace_vtd_page_walk_skip_read(iova, iova_next);
            goto next;
        }

        if (vtd_slpte_nonzero_rsvd(slpte, level)) {
            trace_vtd_page_walk_skip_reserve(iova, iova_next);
            goto next;
        }

        /* Permissions are stacked with parents' */
        read_cur = read && (slpte & VTD_SL_R);
        write_cur = write && (slpte & VTD_SL_W);

        /*
         * As long as we have either read/write permission, this is a
         * valid entry. The rule works for both page entries and page
         * table entries.
         */
        entry_valid = read_cur | write_cur;

        if (!vtd_is_last_slpte(slpte, level) && entry_valid) {
            /*
             * This is a valid PDE (or even bigger than PDE).  We need
             * to walk one further level.
             */
            ret = vtd_page_walk_level(vtd_get_slpte_addr(slpte, info->aw),
                                      iova, MIN(iova_next, end), level - 1,
                                      read_cur, write_cur, info);
        } else {
            /*
             * This means we are either:
             *
             * (1) the real page entry (either 4K page, or huge page)
             * (2) the whole range is invalid
             *
             * In either case, we send an IOTLB notification down.
             */
            entry.target_as = &address_space_memory;
            entry.iova = iova & subpage_mask;
            entry.perm = IOMMU_ACCESS_FLAG(read_cur, write_cur);
            entry.addr_mask = ~subpage_mask;
            /* NOTE: this is only meaningful if entry_valid == true */
            entry.translated_addr = vtd_get_slpte_addr(slpte, info->aw);
            ret = vtd_page_walk_one(&entry, info);
        }

        if (ret < 0) {
            return ret;
        }

next:
        iova = iova_next;
    }

    return 0;
}

/**
 * vtd_page_walk - walk specific IOVA range, and call the hook
 *
 * @s: intel iommu state
 * @ce: context entry to walk upon
 * @start: IOVA address to start the walk
 * @end: IOVA range end address (start <= addr < end)
 * @info: page walking information struct
 */
static int vtd_page_walk(IntelIOMMUState *s, VTDContextEntry *ce,
                         uint64_t start, uint64_t end,
                         vtd_page_walk_info *info)
{
    dma_addr_t addr = vtd_get_iova_pgtbl_base(s, ce);
    uint32_t level = vtd_get_iova_level(s, ce);

    if (!vtd_iova_range_check(s, start, ce, info->aw)) {
        return -VTD_FR_ADDR_BEYOND_MGAW;
    }

    if (!vtd_iova_range_check(s, end, ce, info->aw)) {
        /* Fix end so that it reaches the maximum */
        end = vtd_iova_limit(s, ce, info->aw);
    }

    return vtd_page_walk_level(addr, start, end, level, true, true, info);
}

static int vtd_root_entry_rsvd_bits_check(IntelIOMMUState *s,
                                          VTDRootEntry *re)
{
    /* Legacy Mode reserved bits check */
    if (!s->root_scalable &&
        (re->hi || (re->lo & VTD_ROOT_ENTRY_RSVD(s->aw_bits))))
        goto rsvd_err;

    /* Scalable Mode reserved bits check */
    if (s->root_scalable &&
        ((re->lo & VTD_ROOT_ENTRY_RSVD(s->aw_bits)) ||
         (re->hi & VTD_ROOT_ENTRY_RSVD(s->aw_bits))))
        goto rsvd_err;

    return 0;

rsvd_err:
    error_report_once("%s: invalid root entry: hi=0x%"PRIx64
                      ", lo=0x%"PRIx64,
                      __func__, re->hi, re->lo);
    return -VTD_FR_ROOT_ENTRY_RSVD;
}

static inline int vtd_context_entry_rsvd_bits_check(IntelIOMMUState *s,
                                                    VTDContextEntry *ce)
{
    if (!s->root_scalable &&
        (ce->hi & VTD_CONTEXT_ENTRY_RSVD_HI ||
         ce->lo & VTD_CONTEXT_ENTRY_RSVD_LO(s->aw_bits))) {
        error_report_once("%s: invalid context entry: hi=%"PRIx64
                          ", lo=%"PRIx64" (reserved nonzero)",
                          __func__, ce->hi, ce->lo);
        return -VTD_FR_CONTEXT_ENTRY_RSVD;
    }

    if (s->root_scalable &&
        (ce->val[0] & VTD_SM_CONTEXT_ENTRY_RSVD_VAL0(s->aw_bits) ||
         ce->val[1] & VTD_SM_CONTEXT_ENTRY_RSVD_VAL1 ||
         ce->val[2] ||
         ce->val[3])) {
        error_report_once("%s: invalid context entry: val[3]=%"PRIx64
                          ", val[2]=%"PRIx64
                          ", val[1]=%"PRIx64
                          ", val[0]=%"PRIx64" (reserved nonzero)",
                          __func__, ce->val[3], ce->val[2],
                          ce->val[1], ce->val[0]);
        return -VTD_FR_CONTEXT_ENTRY_RSVD;
    }

    return 0;
}

static int vtd_ce_rid2pasid_check(IntelIOMMUState *s,
                                  VTDContextEntry *ce)
{
    VTDPASIDEntry pe;

    /*
     * Make sure in Scalable Mode, a present context entry
     * has valid rid2pasid setting, which includes valid
     * rid2pasid field and corresponding pasid entry setting
     */
    return vtd_ce_get_rid2pasid_entry(s, ce, &pe);
}

/* Map a device to its corresponding domain (context-entry) */
static int vtd_dev_to_context_entry(IntelIOMMUState *s, uint8_t bus_num,
                                    uint8_t devfn, VTDContextEntry *ce)
{
    VTDRootEntry re;
    int ret_fr;
    X86IOMMUState *x86_iommu = X86_IOMMU_DEVICE(s);

    ret_fr = vtd_get_root_entry(s, bus_num, &re);
    if (ret_fr) {
        return ret_fr;
    }

    if (!vtd_root_entry_present(s, &re, devfn)) {
        /* Not error - it's okay we don't have root entry. */
        trace_vtd_re_not_present(bus_num);
        return -VTD_FR_ROOT_ENTRY_P;
    }

    ret_fr = vtd_root_entry_rsvd_bits_check(s, &re);
    if (ret_fr) {
        return ret_fr;
    }

    ret_fr = vtd_get_context_entry_from_root(s, &re, devfn, ce);
    if (ret_fr) {
        return ret_fr;
    }

    if (!vtd_ce_present(ce)) {
        /* Not error - it's okay we don't have context entry. */
        trace_vtd_ce_not_present(bus_num, devfn);
        return -VTD_FR_CONTEXT_ENTRY_P;
    }

    ret_fr = vtd_context_entry_rsvd_bits_check(s, ce);
    if (ret_fr) {
        return ret_fr;
    }

    /* Check if the programming of context-entry is valid */
    if (!s->root_scalable &&
        !vtd_is_level_supported(s, vtd_ce_get_level(ce))) {
        error_report_once("%s: invalid context entry: hi=%"PRIx64
                          ", lo=%"PRIx64" (level %d not supported)",
                          __func__, ce->hi, ce->lo,
                          vtd_ce_get_level(ce));
        return -VTD_FR_CONTEXT_ENTRY_INV;
    }

    if (!s->root_scalable) {
        /* Do translation type check */
        if (!vtd_ce_type_check(x86_iommu, ce)) {
            /* Errors dumped in vtd_ce_type_check() */
            return -VTD_FR_CONTEXT_ENTRY_INV;
        }
    } else {
        /*
         * Check if the programming of context-entry.rid2pasid
         * and corresponding pasid setting is valid, and thus
         * avoids to check pasid entry fetching result in future
         * helper function calling.
         */
        ret_fr = vtd_ce_rid2pasid_check(s, ce);
        if (ret_fr) {
            return ret_fr;
        }
    }

    return 0;
}

static int vtd_sync_shadow_page_hook(IOMMUTLBEntry *entry,
                                     void *private)
{
    memory_region_notify_iommu((IOMMUMemoryRegion *)private, 0, *entry);
    return 0;
}

static uint16_t vtd_get_domain_id(IntelIOMMUState *s,
                                  VTDContextEntry *ce)
{
    VTDPASIDEntry pe;

    if (s->root_scalable) {
        vtd_ce_get_rid2pasid_entry(s, ce, &pe);
        return VTD_SM_PASID_ENTRY_DID(pe.val[1]);
    }

    return VTD_CONTEXT_ENTRY_DID(ce->hi);
}

static int vtd_sync_shadow_page_table_range(VTDAddressSpace *vtd_as,
                                            VTDContextEntry *ce,
                                            hwaddr addr, hwaddr size)
{
    IntelIOMMUState *s = vtd_as->iommu_state;
    vtd_page_walk_info info = {
        .hook_fn = vtd_sync_shadow_page_hook,
        .private = (void *)&vtd_as->iommu,
        .notify_unmap = true,
        .aw = s->aw_bits,
        .as = vtd_as,
        .domain_id = vtd_get_domain_id(s, ce),
    };

    return vtd_page_walk(s, ce, addr, addr + size, &info);
}

static int vtd_sync_shadow_page_table(VTDAddressSpace *vtd_as)
{
    int ret;
    VTDContextEntry ce;
    IOMMUNotifier *n;

    ret = vtd_dev_to_context_entry(vtd_as->iommu_state,
                                   pci_bus_num(vtd_as->bus),
                                   vtd_as->devfn, &ce);
    if (ret) {
        if (ret == -VTD_FR_CONTEXT_ENTRY_P) {
            /*
             * It's a valid scenario to have a context entry that is
             * not present.  For example, when a device is removed
             * from an existing domain then the context entry will be
             * zeroed by the guest before it was put into another
             * domain.  When this happens, instead of synchronizing
             * the shadow pages we should invalidate all existing
             * mappings and notify the backends.
             */
            IOMMU_NOTIFIER_FOREACH(n, &vtd_as->iommu) {
                vtd_address_space_unmap(vtd_as, n);
            }
            ret = 0;
        }
        return ret;
    }

    return vtd_sync_shadow_page_table_range(vtd_as, &ce, 0, UINT64_MAX);
}

/*
 * Check if specific device is configed to bypass address
 * translation for DMA requests. In Scalable Mode, bypass
 * 1st-level translation or 2nd-level translation, it depends
 * on PGTT setting.
 */
static bool vtd_dev_pt_enabled(VTDAddressSpace *as)
{
    IntelIOMMUState *s;
    VTDContextEntry ce;
    VTDPASIDEntry pe;
    int ret;

    assert(as);

    s = as->iommu_state;
    ret = vtd_dev_to_context_entry(s, pci_bus_num(as->bus),
                                   as->devfn, &ce);
    if (ret) {
        /*
         * Possibly failed to parse the context entry for some reason
         * (e.g., during init, or any guest configuration errors on
         * context entries). We should assume PT not enabled for
         * safety.
         */
        return false;
    }

    if (s->root_scalable) {
        ret = vtd_ce_get_rid2pasid_entry(s, &ce, &pe);
        if (ret) {
            error_report_once("%s: vtd_ce_get_rid2pasid_entry error: %"PRId32,
                              __func__, ret);
            return false;
        }
        return (VTD_PE_GET_TYPE(&pe) == VTD_SM_PASID_ENTRY_PT);
    }

    return (vtd_ce_get_type(&ce) == VTD_CONTEXT_TT_PASS_THROUGH);
}

/* Return whether the device is using IOMMU translation. */
static bool vtd_switch_address_space(VTDAddressSpace *as)
{
    bool use_iommu;
    /* Whether we need to take the BQL on our own */
    bool take_bql = !qemu_mutex_iothread_locked();

    assert(as);

    use_iommu = as->iommu_state->dmar_enabled && !vtd_dev_pt_enabled(as);

    trace_vtd_switch_address_space(pci_bus_num(as->bus),
                                   VTD_PCI_SLOT(as->devfn),
                                   VTD_PCI_FUNC(as->devfn),
                                   use_iommu);

    /*
     * It's possible that we reach here without BQL, e.g., when called
     * from vtd_pt_enable_fast_path(). However the memory APIs need
     * it. We'd better make sure we have had it already, or, take it.
     */
    if (take_bql) {
        qemu_mutex_lock_iothread();
    }

    /* Turn off first then on the other */
    if (use_iommu) {
        memory_region_set_enabled(&as->nodmar, false);
        memory_region_set_enabled(MEMORY_REGION(&as->iommu), true);
    } else {
        memory_region_set_enabled(MEMORY_REGION(&as->iommu), false);
        memory_region_set_enabled(&as->nodmar, true);
    }

    if (take_bql) {
        qemu_mutex_unlock_iothread();
    }

    return use_iommu;
}

static void vtd_switch_address_space_all(IntelIOMMUState *s)
{
    GHashTableIter iter;
    VTDBus *vtd_bus;
    int i;

    g_hash_table_iter_init(&iter, s->vtd_as_by_busptr);
    while (g_hash_table_iter_next(&iter, NULL, (void **)&vtd_bus)) {
        for (i = 0; i < PCI_DEVFN_MAX; i++) {
            if (!vtd_bus->dev_as[i]) {
                continue;
            }
            vtd_switch_address_space(vtd_bus->dev_as[i]);
        }
    }
}

static inline uint16_t vtd_make_source_id(uint8_t bus_num, uint8_t devfn)
{
    return ((bus_num & 0xffUL) << 8) | (devfn & 0xffUL);
}

static const bool vtd_qualified_faults[] = {
    [VTD_FR_RESERVED] = false,
    [VTD_FR_ROOT_ENTRY_P] = false,
    [VTD_FR_CONTEXT_ENTRY_P] = true,
    [VTD_FR_CONTEXT_ENTRY_INV] = true,
    [VTD_FR_ADDR_BEYOND_MGAW] = true,
    [VTD_FR_WRITE] = true,
    [VTD_FR_READ] = true,
    [VTD_FR_PAGING_ENTRY_INV] = true,
    [VTD_FR_ROOT_TABLE_INV] = false,
    [VTD_FR_CONTEXT_TABLE_INV] = false,
    [VTD_FR_ROOT_ENTRY_RSVD] = false,
    [VTD_FR_PAGING_ENTRY_RSVD] = true,
    [VTD_FR_CONTEXT_ENTRY_TT] = true,
    [VTD_FR_PASID_TABLE_INV] = false,
    [VTD_FR_RESERVED_ERR] = false,
    [VTD_FR_MAX] = false,
};

/* To see if a fault condition is "qualified", which is reported to software
 * only if the FPD field in the context-entry used to process the faulting
 * request is 0.
 */
static inline bool vtd_is_qualified_fault(VTDFaultReason fault)
{
    return vtd_qualified_faults[fault];
}

static inline bool vtd_is_interrupt_addr(hwaddr addr)
{
    return VTD_INTERRUPT_ADDR_FIRST <= addr && addr <= VTD_INTERRUPT_ADDR_LAST;
}

static void vtd_pt_enable_fast_path(IntelIOMMUState *s, uint16_t source_id)
{
    VTDBus *vtd_bus;
    VTDAddressSpace *vtd_as;
    bool success = false;

    vtd_bus = vtd_find_as_from_bus_num(s, VTD_SID_TO_BUS(source_id));
    if (!vtd_bus) {
        goto out;
    }

    vtd_as = vtd_bus->dev_as[VTD_SID_TO_DEVFN(source_id)];
    if (!vtd_as) {
        goto out;
    }

    if (vtd_switch_address_space(vtd_as) == false) {
        /* We switched off IOMMU region successfully. */
        success = true;
    }

out:
    trace_vtd_pt_enable_fast_path(source_id, success);
}

/* Map dev to context-entry then do a paging-structures walk to do a iommu
 * translation.
 *
 * Called from RCU critical section.
 *
 * @bus_num: The bus number
 * @devfn: The devfn, which is the  combined of device and function number
 * @is_write: The access is a write operation
 * @entry: IOMMUTLBEntry that contain the addr to be translated and result
 *
 * Returns true if translation is successful, otherwise false.
 */
static bool vtd_do_iommu_translate(VTDAddressSpace *vtd_as, PCIBus *bus,
                                   uint8_t devfn, hwaddr addr, bool is_write,
                                   IOMMUTLBEntry *entry)
{
    IntelIOMMUState *s = vtd_as->iommu_state;
    VTDContextEntry ce;
    uint8_t bus_num = pci_bus_num(bus);
    VTDContextCacheEntry *cc_entry;
    uint64_t slpte, page_mask;
    uint32_t level;
    uint16_t source_id = vtd_make_source_id(bus_num, devfn);
    int ret_fr;
    bool is_fpd_set = false;
    bool reads = true;
    bool writes = true;
    uint8_t access_flags;
    VTDIOTLBEntry *iotlb_entry;

    /*
     * We have standalone memory region for interrupt addresses, we
     * should never receive translation requests in this region.
     */
    assert(!vtd_is_interrupt_addr(addr));

    vtd_iommu_lock(s);

    cc_entry = &vtd_as->context_cache_entry;

    /* Try to fetch slpte form IOTLB */
    iotlb_entry = vtd_lookup_iotlb(s, source_id, addr);
    if (iotlb_entry) {
        trace_vtd_iotlb_page_hit(source_id, addr, iotlb_entry->slpte,
                                 iotlb_entry->domain_id);
        slpte = iotlb_entry->slpte;
        access_flags = iotlb_entry->access_flags;
        page_mask = iotlb_entry->mask;
        goto out;
    }

    /* Try to fetch context-entry from cache first */
    if (cc_entry->context_cache_gen == s->context_cache_gen) {
        trace_vtd_iotlb_cc_hit(bus_num, devfn, cc_entry->context_entry.hi,
                               cc_entry->context_entry.lo,
                               cc_entry->context_cache_gen);
        ce = cc_entry->context_entry;
        is_fpd_set = ce.lo & VTD_CONTEXT_ENTRY_FPD;
        if (!is_fpd_set && s->root_scalable) {
            ret_fr = vtd_ce_get_pasid_fpd(s, &ce, &is_fpd_set);
            VTD_PE_GET_FPD_ERR(ret_fr, is_fpd_set, s, source_id, addr, is_write);
        }
    } else {
        ret_fr = vtd_dev_to_context_entry(s, bus_num, devfn, &ce);
        is_fpd_set = ce.lo & VTD_CONTEXT_ENTRY_FPD;
        if (!ret_fr && !is_fpd_set && s->root_scalable) {
            ret_fr = vtd_ce_get_pasid_fpd(s, &ce, &is_fpd_set);
        }
        VTD_PE_GET_FPD_ERR(ret_fr, is_fpd_set, s, source_id, addr, is_write);
        /* Update context-cache */
        trace_vtd_iotlb_cc_update(bus_num, devfn, ce.hi, ce.lo,
                                  cc_entry->context_cache_gen,
                                  s->context_cache_gen);
        cc_entry->context_entry = ce;
        cc_entry->context_cache_gen = s->context_cache_gen;
    }

    /*
     * We don't need to translate for pass-through context entries.
     * Also, let's ignore IOTLB caching as well for PT devices.
     */
    if (vtd_ce_get_type(&ce) == VTD_CONTEXT_TT_PASS_THROUGH) {
        entry->iova = addr & VTD_PAGE_MASK_4K;
        entry->translated_addr = entry->iova;
        entry->addr_mask = ~VTD_PAGE_MASK_4K;
        entry->perm = IOMMU_RW;
        trace_vtd_translate_pt(source_id, entry->iova);

        /*
         * When this happens, it means firstly caching-mode is not
         * enabled, and this is the first passthrough translation for
         * the device. Let's enable the fast path for passthrough.
         *
         * When passthrough is disabled again for the device, we can
         * capture it via the context entry invalidation, then the
         * IOMMU region can be swapped back.
         */
        vtd_pt_enable_fast_path(s, source_id);
        vtd_iommu_unlock(s);
        return true;
    }

    ret_fr = vtd_iova_to_slpte(s, &ce, addr, is_write, &slpte, &level,
                               &reads, &writes, s->aw_bits);
    VTD_PE_GET_FPD_ERR(ret_fr, is_fpd_set, s, source_id, addr, is_write);

    page_mask = vtd_slpt_level_page_mask(level);
    access_flags = IOMMU_ACCESS_FLAG(reads, writes);
    vtd_update_iotlb(s, source_id, vtd_get_domain_id(s, &ce), addr, slpte,
                     access_flags, level);
out:
    vtd_iommu_unlock(s);
    entry->iova = addr & page_mask;
    entry->translated_addr = vtd_get_slpte_addr(slpte, s->aw_bits) & page_mask;
    entry->addr_mask = ~page_mask;
    entry->perm = access_flags;
    return true;

error:
    vtd_iommu_unlock(s);
    entry->iova = 0;
    entry->translated_addr = 0;
    entry->addr_mask = 0;
    entry->perm = IOMMU_NONE;
    return false;
}

static void vtd_root_table_setup(IntelIOMMUState *s)
{
    s->root = vtd_get_quad_raw(s, DMAR_RTADDR_REG);
    s->root &= VTD_RTADDR_ADDR_MASK(s->aw_bits);

    vtd_update_scalable_state(s);

    trace_vtd_reg_dmar_root(s->root, s->root_scalable);
}

static void vtd_iec_notify_all(IntelIOMMUState *s, bool global,
                               uint32_t index, uint32_t mask)
{
    x86_iommu_iec_notify_all(X86_IOMMU_DEVICE(s), global, index, mask);
}

static void vtd_interrupt_remap_table_setup(IntelIOMMUState *s)
{
    uint64_t value = 0;
    value = vtd_get_quad_raw(s, DMAR_IRTA_REG);
    s->intr_size = 1UL << ((value & VTD_IRTA_SIZE_MASK) + 1);
    s->intr_root = value & VTD_IRTA_ADDR_MASK(s->aw_bits);
    s->intr_eime = value & VTD_IRTA_EIME;

    /* Notify global invalidation */
    vtd_iec_notify_all(s, true, 0, 0);

    trace_vtd_reg_ir_root(s->intr_root, s->intr_size);
}

static void vtd_iommu_replay_all(IntelIOMMUState *s)
{
    VTDAddressSpace *vtd_as;

    QLIST_FOREACH(vtd_as, &s->vtd_as_with_notifiers, next) {
        vtd_sync_shadow_page_table(vtd_as);
    }
}

static void vtd_context_global_invalidate(IntelIOMMUState *s)
{
    trace_vtd_inv_desc_cc_global();
    /* Protects context cache */
    vtd_iommu_lock(s);
    s->context_cache_gen++;
    if (s->context_cache_gen == VTD_CONTEXT_CACHE_GEN_MAX) {
        vtd_reset_context_cache_locked(s);
    }
    vtd_iommu_unlock(s);
    vtd_address_space_refresh_all(s);
    /*
     * From VT-d spec 6.5.2.1, a global context entry invalidation
     * should be followed by a IOTLB global invalidation, so we should
     * be safe even without this. Hoewever, let's replay the region as
     * well to be safer, and go back here when we need finer tunes for
     * VT-d emulation codes.
     */
    vtd_iommu_replay_all(s);
}

/* Do a context-cache device-selective invalidation.
 * @func_mask: FM field after shifting
 */
static void vtd_context_device_invalidate(IntelIOMMUState *s,
                                          uint16_t source_id,
                                          uint16_t func_mask)
{
    uint16_t mask;
    VTDBus *vtd_bus;
    VTDAddressSpace *vtd_as;
    uint8_t bus_n, devfn;
    uint16_t devfn_it;

    trace_vtd_inv_desc_cc_devices(source_id, func_mask);

    switch (func_mask & 3) {
    case 0:
        mask = 0;   /* No bits in the SID field masked */
        break;
    case 1:
        mask = 4;   /* Mask bit 2 in the SID field */
        break;
    case 2:
        mask = 6;   /* Mask bit 2:1 in the SID field */
        break;
    case 3:
        mask = 7;   /* Mask bit 2:0 in the SID field */
        break;
    }
    mask = ~mask;

    bus_n = VTD_SID_TO_BUS(source_id);
    vtd_bus = vtd_find_as_from_bus_num(s, bus_n);
    if (vtd_bus) {
        devfn = VTD_SID_TO_DEVFN(source_id);
        for (devfn_it = 0; devfn_it < PCI_DEVFN_MAX; ++devfn_it) {
            vtd_as = vtd_bus->dev_as[devfn_it];
            if (vtd_as && ((devfn_it & mask) == (devfn & mask))) {
                trace_vtd_inv_desc_cc_device(bus_n, VTD_PCI_SLOT(devfn_it),
                                             VTD_PCI_FUNC(devfn_it));
                vtd_iommu_lock(s);
                vtd_as->context_cache_entry.context_cache_gen = 0;
                vtd_iommu_unlock(s);
                /*
                 * Do switch address space when needed, in case if the
                 * device passthrough bit is switched.
                 */
                vtd_switch_address_space(vtd_as);
                /*
                 * So a device is moving out of (or moving into) a
                 * domain, resync the shadow page table.
                 * This won't bring bad even if we have no such
                 * notifier registered - the IOMMU notification
                 * framework will skip MAP notifications if that
                 * happened.
                 */
                vtd_sync_shadow_page_table(vtd_as);
            }
        }
    }
}

/* Context-cache invalidation
 * Returns the Context Actual Invalidation Granularity.
 * @val: the content of the CCMD_REG
 */
static uint64_t vtd_context_cache_invalidate(IntelIOMMUState *s, uint64_t val)
{
    uint64_t caig;
    uint64_t type = val & VTD_CCMD_CIRG_MASK;

    switch (type) {
    case VTD_CCMD_DOMAIN_INVL:
        /* Fall through */
    case VTD_CCMD_GLOBAL_INVL:
        caig = VTD_CCMD_GLOBAL_INVL_A;
        vtd_context_global_invalidate(s);
        break;

    case VTD_CCMD_DEVICE_INVL:
        caig = VTD_CCMD_DEVICE_INVL_A;
        vtd_context_device_invalidate(s, VTD_CCMD_SID(val), VTD_CCMD_FM(val));
        break;

    default:
        error_report_once("%s: invalid context: 0x%" PRIx64,
                          __func__, val);
        caig = 0;
    }
    return caig;
}

static void vtd_iotlb_global_invalidate(IntelIOMMUState *s)
{
    trace_vtd_inv_desc_iotlb_global();
    vtd_reset_iotlb(s);
    vtd_iommu_replay_all(s);
}

static void vtd_iotlb_domain_invalidate(IntelIOMMUState *s, uint16_t domain_id)
{
    VTDContextEntry ce;
    VTDAddressSpace *vtd_as;

    trace_vtd_inv_desc_iotlb_domain(domain_id);

    vtd_iommu_lock(s);
    g_hash_table_foreach_remove(s->iotlb, vtd_hash_remove_by_domain,
                                &domain_id);
    vtd_iommu_unlock(s);

    QLIST_FOREACH(vtd_as, &s->vtd_as_with_notifiers, next) {
        if (!vtd_dev_to_context_entry(s, pci_bus_num(vtd_as->bus),
                                      vtd_as->devfn, &ce) &&
            domain_id == vtd_get_domain_id(s, &ce)) {
            vtd_sync_shadow_page_table(vtd_as);
        }
    }
}

static void vtd_iotlb_page_invalidate_notify(IntelIOMMUState *s,
                                           uint16_t domain_id, hwaddr addr,
                                           uint8_t am)
{
    VTDAddressSpace *vtd_as;
    VTDContextEntry ce;
    int ret;
    hwaddr size = (1 << am) * VTD_PAGE_SIZE;

    QLIST_FOREACH(vtd_as, &(s->vtd_as_with_notifiers), next) {
        ret = vtd_dev_to_context_entry(s, pci_bus_num(vtd_as->bus),
                                       vtd_as->devfn, &ce);
        if (!ret && domain_id == vtd_get_domain_id(s, &ce)) {
            if (vtd_as_has_map_notifier(vtd_as)) {
                /*
                 * As long as we have MAP notifications registered in
                 * any of our IOMMU notifiers, we need to sync the
                 * shadow page table.
                 */
                vtd_sync_shadow_page_table_range(vtd_as, &ce, addr, size);
            } else {
                /*
                 * For UNMAP-only notifiers, we don't need to walk the
                 * page tables.  We just deliver the PSI down to
                 * invalidate caches.
                 */
                IOMMUTLBEntry entry = {
                    .target_as = &address_space_memory,
                    .iova = addr,
                    .translated_addr = 0,
                    .addr_mask = size - 1,
                    .perm = IOMMU_NONE,
                };
                memory_region_notify_iommu(&vtd_as->iommu, 0, entry);
            }
        }
    }
}

static void vtd_iotlb_page_invalidate(IntelIOMMUState *s, uint16_t domain_id,
                                      hwaddr addr, uint8_t am)
{
    VTDIOTLBPageInvInfo info;

    trace_vtd_inv_desc_iotlb_pages(domain_id, addr, am);

    assert(am <= VTD_MAMV);
    info.domain_id = domain_id;
    info.addr = addr;
    info.mask = ~((1 << am) - 1);
    vtd_iommu_lock(s);
    g_hash_table_foreach_remove(s->iotlb, vtd_hash_remove_by_page, &info);
    vtd_iommu_unlock(s);
    vtd_iotlb_page_invalidate_notify(s, domain_id, addr, am);
}

/* Flush IOTLB
 * Returns the IOTLB Actual Invalidation Granularity.
 * @val: the content of the IOTLB_REG
 */
static uint64_t vtd_iotlb_flush(IntelIOMMUState *s, uint64_t val)
{
    uint64_t iaig;
    uint64_t type = val & VTD_TLB_FLUSH_GRANU_MASK;
    uint16_t domain_id;
    hwaddr addr;
    uint8_t am;

    switch (type) {
    case VTD_TLB_GLOBAL_FLUSH:
        iaig = VTD_TLB_GLOBAL_FLUSH_A;
        vtd_iotlb_global_invalidate(s);
        break;

    case VTD_TLB_DSI_FLUSH:
        domain_id = VTD_TLB_DID(val);
        iaig = VTD_TLB_DSI_FLUSH_A;
        vtd_iotlb_domain_invalidate(s, domain_id);
        break;

    case VTD_TLB_PSI_FLUSH:
        domain_id = VTD_TLB_DID(val);
        addr = vtd_get_quad_raw(s, DMAR_IVA_REG);
        am = VTD_IVA_AM(addr);
        addr = VTD_IVA_ADDR(addr);
        if (am > VTD_MAMV) {
            error_report_once("%s: address mask overflow: 0x%" PRIx64,
                              __func__, vtd_get_quad_raw(s, DMAR_IVA_REG));
            iaig = 0;
            break;
        }
        iaig = VTD_TLB_PSI_FLUSH_A;
        vtd_iotlb_page_invalidate(s, domain_id, addr, am);
        break;

    default:
        error_report_once("%s: invalid granularity: 0x%" PRIx64,
                          __func__, val);
        iaig = 0;
    }
    return iaig;
}

static void vtd_fetch_inv_desc(IntelIOMMUState *s);

static inline bool vtd_queued_inv_disable_check(IntelIOMMUState *s)
{
    return s->qi_enabled && (s->iq_tail == s->iq_head) &&
           (s->iq_last_desc_type == VTD_INV_DESC_WAIT);
}

static void vtd_handle_gcmd_qie(IntelIOMMUState *s, bool en)
{
    uint64_t iqa_val = vtd_get_quad_raw(s, DMAR_IQA_REG);

    trace_vtd_inv_qi_enable(en);

    if (en) {
        s->iq = iqa_val & VTD_IQA_IQA_MASK(s->aw_bits);
        /* 2^(x+8) entries */
        s->iq_size = 1UL << ((iqa_val & VTD_IQA_QS) + 8 - (s->iq_dw ? 1 : 0));
        s->qi_enabled = true;
        trace_vtd_inv_qi_setup(s->iq, s->iq_size);
        /* Ok - report back to driver */
        vtd_set_clear_mask_long(s, DMAR_GSTS_REG, 0, VTD_GSTS_QIES);

        if (s->iq_tail != 0) {
            /*
             * This is a spec violation but Windows guests are known to set up
             * Queued Invalidation this way so we allow the write and process
             * Invalidation Descriptors right away.
             */
            trace_vtd_warn_invalid_qi_tail(s->iq_tail);
            if (!(vtd_get_long_raw(s, DMAR_FSTS_REG) & VTD_FSTS_IQE)) {
                vtd_fetch_inv_desc(s);
            }
        }
    } else {
        if (vtd_queued_inv_disable_check(s)) {
            /* disable Queued Invalidation */
            vtd_set_quad_raw(s, DMAR_IQH_REG, 0);
            s->iq_head = 0;
            s->qi_enabled = false;
            /* Ok - report back to driver */
            vtd_set_clear_mask_long(s, DMAR_GSTS_REG, VTD_GSTS_QIES, 0);
        } else {
            error_report_once("%s: detected improper state when disable QI "
                              "(head=0x%x, tail=0x%x, last_type=%d)",
                              __func__,
                              s->iq_head, s->iq_tail, s->iq_last_desc_type);
        }
    }
}

/* Set Root Table Pointer */
static void vtd_handle_gcmd_srtp(IntelIOMMUState *s)
{
    vtd_root_table_setup(s);
    /* Ok - report back to driver */
    vtd_set_clear_mask_long(s, DMAR_GSTS_REG, 0, VTD_GSTS_RTPS);
    vtd_reset_caches(s);
    vtd_address_space_refresh_all(s);
}

/* Set Interrupt Remap Table Pointer */
static void vtd_handle_gcmd_sirtp(IntelIOMMUState *s)
{
    vtd_interrupt_remap_table_setup(s);
    /* Ok - report back to driver */
    vtd_set_clear_mask_long(s, DMAR_GSTS_REG, 0, VTD_GSTS_IRTPS);
}

/* Handle Translation Enable/Disable */
static void vtd_handle_gcmd_te(IntelIOMMUState *s, bool en)
{
    if (s->dmar_enabled == en) {
        return;
    }

    trace_vtd_dmar_enable(en);

    if (en) {
        s->dmar_enabled = true;
        /* Ok - report back to driver */
        vtd_set_clear_mask_long(s, DMAR_GSTS_REG, 0, VTD_GSTS_TES);
    } else {
        s->dmar_enabled = false;

        /* Clear the index of Fault Recording Register */
        s->next_frcd_reg = 0;
        /* Ok - report back to driver */
        vtd_set_clear_mask_long(s, DMAR_GSTS_REG, VTD_GSTS_TES, 0);
    }

    vtd_reset_caches(s);
    vtd_address_space_refresh_all(s);
}

/* Handle Interrupt Remap Enable/Disable */
static void vtd_handle_gcmd_ire(IntelIOMMUState *s, bool en)
{
    trace_vtd_ir_enable(en);

    if (en) {
        s->intr_enabled = true;
        /* Ok - report back to driver */
        vtd_set_clear_mask_long(s, DMAR_GSTS_REG, 0, VTD_GSTS_IRES);
    } else {
        s->intr_enabled = false;
        /* Ok - report back to driver */
        vtd_set_clear_mask_long(s, DMAR_GSTS_REG, VTD_GSTS_IRES, 0);
    }
}

/* Handle write to Global Command Register */
static void vtd_handle_gcmd_write(IntelIOMMUState *s)
{
    uint32_t status = vtd_get_long_raw(s, DMAR_GSTS_REG);
    uint32_t val = vtd_get_long_raw(s, DMAR_GCMD_REG);
    uint32_t changed = status ^ val;

    trace_vtd_reg_write_gcmd(status, val);
    if (changed & VTD_GCMD_TE) {
        /* Translation enable/disable */
        vtd_handle_gcmd_te(s, val & VTD_GCMD_TE);
    }
    if (val & VTD_GCMD_SRTP) {
        /* Set/update the root-table pointer */
        vtd_handle_gcmd_srtp(s);
    }
    if (changed & VTD_GCMD_QIE) {
        /* Queued Invalidation Enable */
        vtd_handle_gcmd_qie(s, val & VTD_GCMD_QIE);
    }
    if (val & VTD_GCMD_SIRTP) {
        /* Set/update the interrupt remapping root-table pointer */
        vtd_handle_gcmd_sirtp(s);
    }
    if (changed & VTD_GCMD_IRE) {
        /* Interrupt remap enable/disable */
        vtd_handle_gcmd_ire(s, val & VTD_GCMD_IRE);
    }
}

/* Handle write to Context Command Register */
static void vtd_handle_ccmd_write(IntelIOMMUState *s)
{
    uint64_t ret;
    uint64_t val = vtd_get_quad_raw(s, DMAR_CCMD_REG);

    /* Context-cache invalidation request */
    if (val & VTD_CCMD_ICC) {
        if (s->qi_enabled) {
            error_report_once("Queued Invalidation enabled, "
                              "should not use register-based invalidation");
            return;
        }
        ret = vtd_context_cache_invalidate(s, val);
        /* Invalidation completed. Change something to show */
        vtd_set_clear_mask_quad(s, DMAR_CCMD_REG, VTD_CCMD_ICC, 0ULL);
        ret = vtd_set_clear_mask_quad(s, DMAR_CCMD_REG, VTD_CCMD_CAIG_MASK,
                                      ret);
    }
}

/* Handle write to IOTLB Invalidation Register */
static void vtd_handle_iotlb_write(IntelIOMMUState *s)
{
    uint64_t ret;
    uint64_t val = vtd_get_quad_raw(s, DMAR_IOTLB_REG);

    /* IOTLB invalidation request */
    if (val & VTD_TLB_IVT) {
        if (s->qi_enabled) {
            error_report_once("Queued Invalidation enabled, "
                              "should not use register-based invalidation");
            return;
        }
        ret = vtd_iotlb_flush(s, val);
        /* Invalidation completed. Change something to show */
        vtd_set_clear_mask_quad(s, DMAR_IOTLB_REG, VTD_TLB_IVT, 0ULL);
        ret = vtd_set_clear_mask_quad(s, DMAR_IOTLB_REG,
                                      VTD_TLB_FLUSH_GRANU_MASK_A, ret);
    }
}

/* Fetch an Invalidation Descriptor from the Invalidation Queue */
static bool vtd_get_inv_desc(IntelIOMMUState *s,
                             VTDInvDesc *inv_desc)
{
    dma_addr_t base_addr = s->iq;
    uint32_t offset = s->iq_head;
    uint32_t dw = s->iq_dw ? 32 : 16;
    dma_addr_t addr = base_addr + offset * dw;

    if (dma_memory_read(&address_space_memory, addr, inv_desc, dw)) {
        error_report_once("Read INV DESC failed.");
        return false;
    }
    inv_desc->lo = le64_to_cpu(inv_desc->lo);
    inv_desc->hi = le64_to_cpu(inv_desc->hi);
    if (dw == 32) {
        inv_desc->val[2] = le64_to_cpu(inv_desc->val[2]);
        inv_desc->val[3] = le64_to_cpu(inv_desc->val[3]);
    }
    return true;
}

static bool vtd_process_wait_desc(IntelIOMMUState *s, VTDInvDesc *inv_desc)
{
    if ((inv_desc->hi & VTD_INV_DESC_WAIT_RSVD_HI) ||
        (inv_desc->lo & VTD_INV_DESC_WAIT_RSVD_LO)) {
        error_report_once("%s: invalid wait desc: hi=%"PRIx64", lo=%"PRIx64
                          " (reserved nonzero)", __func__, inv_desc->hi,
                          inv_desc->lo);
        return false;
    }
    if (inv_desc->lo & VTD_INV_DESC_WAIT_SW) {
        /* Status Write */
        uint32_t status_data = (uint32_t)(inv_desc->lo >>
                               VTD_INV_DESC_WAIT_DATA_SHIFT);

        assert(!(inv_desc->lo & VTD_INV_DESC_WAIT_IF));

        /* FIXME: need to be masked with HAW? */
        dma_addr_t status_addr = inv_desc->hi;
        trace_vtd_inv_desc_wait_sw(status_addr, status_data);
        status_data = cpu_to_le32(status_data);
        if (dma_memory_write(&address_space_memory, status_addr, &status_data,
                             sizeof(status_data))) {
            trace_vtd_inv_desc_wait_write_fail(inv_desc->hi, inv_desc->lo);
            return false;
        }
    } else if (inv_desc->lo & VTD_INV_DESC_WAIT_IF) {
        /* Interrupt flag */
        vtd_generate_completion_event(s);
    } else {
        error_report_once("%s: invalid wait desc: hi=%"PRIx64", lo=%"PRIx64
                          " (unknown type)", __func__, inv_desc->hi,
                          inv_desc->lo);
        return false;
    }
    return true;
}

static bool vtd_process_context_cache_desc(IntelIOMMUState *s,
                                           VTDInvDesc *inv_desc)
{
    uint16_t sid, fmask;

    if ((inv_desc->lo & VTD_INV_DESC_CC_RSVD) || inv_desc->hi) {
        error_report_once("%s: invalid cc inv desc: hi=%"PRIx64", lo=%"PRIx64
                          " (reserved nonzero)", __func__, inv_desc->hi,
                          inv_desc->lo);
        return false;
    }
    switch (inv_desc->lo & VTD_INV_DESC_CC_G) {
    case VTD_INV_DESC_CC_DOMAIN:
        trace_vtd_inv_desc_cc_domain(
            (uint16_t)VTD_INV_DESC_CC_DID(inv_desc->lo));
        /* Fall through */
    case VTD_INV_DESC_CC_GLOBAL:
        vtd_context_global_invalidate(s);
        break;

    case VTD_INV_DESC_CC_DEVICE:
        sid = VTD_INV_DESC_CC_SID(inv_desc->lo);
        fmask = VTD_INV_DESC_CC_FM(inv_desc->lo);
        vtd_context_device_invalidate(s, sid, fmask);
        break;

    default:
        error_report_once("%s: invalid cc inv desc: hi=%"PRIx64", lo=%"PRIx64
                          " (invalid type)", __func__, inv_desc->hi,
                          inv_desc->lo);
        return false;
    }
    return true;
}

static bool vtd_process_iotlb_desc(IntelIOMMUState *s, VTDInvDesc *inv_desc)
{
    uint16_t domain_id;
    uint8_t am;
    hwaddr addr;

    if ((inv_desc->lo & VTD_INV_DESC_IOTLB_RSVD_LO) ||
        (inv_desc->hi & VTD_INV_DESC_IOTLB_RSVD_HI)) {
        error_report_once("%s: invalid iotlb inv desc: hi=0x%"PRIx64
                          ", lo=0x%"PRIx64" (reserved bits unzero)\n",
                          __func__, inv_desc->hi, inv_desc->lo);
        return false;
    }

    switch (inv_desc->lo & VTD_INV_DESC_IOTLB_G) {
    case VTD_INV_DESC_IOTLB_GLOBAL:
        vtd_iotlb_global_invalidate(s);
        break;

    case VTD_INV_DESC_IOTLB_DOMAIN:
        domain_id = VTD_INV_DESC_IOTLB_DID(inv_desc->lo);
        vtd_iotlb_domain_invalidate(s, domain_id);
        break;

    case VTD_INV_DESC_IOTLB_PAGE:
        domain_id = VTD_INV_DESC_IOTLB_DID(inv_desc->lo);
        addr = VTD_INV_DESC_IOTLB_ADDR(inv_desc->hi);
        am = VTD_INV_DESC_IOTLB_AM(inv_desc->hi);
        if (am > VTD_MAMV) {
            error_report_once("%s: invalid iotlb inv desc: hi=0x%"PRIx64
                              ", lo=0x%"PRIx64" (am=%u > VTD_MAMV=%u)\n",
                              __func__, inv_desc->hi, inv_desc->lo,
                              am, (unsigned)VTD_MAMV);
            return false;
        }
        vtd_iotlb_page_invalidate(s, domain_id, addr, am);
        break;

    default:
        error_report_once("%s: invalid iotlb inv desc: hi=0x%"PRIx64
                          ", lo=0x%"PRIx64" (type mismatch: 0x%llx)\n",
                          __func__, inv_desc->hi, inv_desc->lo,
                          inv_desc->lo & VTD_INV_DESC_IOTLB_G);
        return false;
    }
    return true;
}

static bool vtd_process_inv_iec_desc(IntelIOMMUState *s,
                                     VTDInvDesc *inv_desc)
{
    trace_vtd_inv_desc_iec(inv_desc->iec.granularity,
                           inv_desc->iec.index,
                           inv_desc->iec.index_mask);

    vtd_iec_notify_all(s, !inv_desc->iec.granularity,
                       inv_desc->iec.index,
                       inv_desc->iec.index_mask);
    return true;
}

static bool vtd_process_device_iotlb_desc(IntelIOMMUState *s,
                                          VTDInvDesc *inv_desc)
{
    VTDAddressSpace *vtd_dev_as;
    IOMMUTLBEntry entry;
    struct VTDBus *vtd_bus;
    hwaddr addr;
    uint64_t sz;
    uint16_t sid;
    uint8_t devfn;
    bool size;
    uint8_t bus_num;

    addr = VTD_INV_DESC_DEVICE_IOTLB_ADDR(inv_desc->hi);
    sid = VTD_INV_DESC_DEVICE_IOTLB_SID(inv_desc->lo);
    devfn = sid & 0xff;
    bus_num = sid >> 8;
    size = VTD_INV_DESC_DEVICE_IOTLB_SIZE(inv_desc->hi);

    if ((inv_desc->lo & VTD_INV_DESC_DEVICE_IOTLB_RSVD_LO) ||
        (inv_desc->hi & VTD_INV_DESC_DEVICE_IOTLB_RSVD_HI)) {
        error_report_once("%s: invalid dev-iotlb inv desc: hi=%"PRIx64
                          ", lo=%"PRIx64" (reserved nonzero)", __func__,
                          inv_desc->hi, inv_desc->lo);
        return false;
    }

    vtd_bus = vtd_find_as_from_bus_num(s, bus_num);
    if (!vtd_bus) {
        goto done;
    }

    vtd_dev_as = vtd_bus->dev_as[devfn];
    if (!vtd_dev_as) {
        goto done;
    }

    /* According to ATS spec table 2.4:
     * S = 0, bits 15:12 = xxxx     range size: 4K
     * S = 1, bits 15:12 = xxx0     range size: 8K
     * S = 1, bits 15:12 = xx01     range size: 16K
     * S = 1, bits 15:12 = x011     range size: 32K
     * S = 1, bits 15:12 = 0111     range size: 64K
     * ...
     */
    if (size) {
        sz = (VTD_PAGE_SIZE * 2) << cto64(addr >> VTD_PAGE_SHIFT);
        addr &= ~(sz - 1);
    } else {
        sz = VTD_PAGE_SIZE;
    }

    entry.target_as = &vtd_dev_as->as;
    entry.addr_mask = sz - 1;
    entry.iova = addr;
    entry.perm = IOMMU_NONE;
    entry.translated_addr = 0;
    memory_region_notify_iommu(&vtd_dev_as->iommu, 0, entry);

done:
    return true;
}

static bool vtd_process_inv_desc(IntelIOMMUState *s)
{
    VTDInvDesc inv_desc;
    uint8_t desc_type;

    trace_vtd_inv_qi_head(s->iq_head);
    if (!vtd_get_inv_desc(s, &inv_desc)) {
        s->iq_last_desc_type = VTD_INV_DESC_NONE;
        return false;
    }

    desc_type = inv_desc.lo & VTD_INV_DESC_TYPE;
    /* FIXME: should update at first or at last? */
    s->iq_last_desc_type = desc_type;

    switch (desc_type) {
    case VTD_INV_DESC_CC:
        trace_vtd_inv_desc("context-cache", inv_desc.hi, inv_desc.lo);
        if (!vtd_process_context_cache_desc(s, &inv_desc)) {
            return false;
        }
        break;

    case VTD_INV_DESC_IOTLB:
        trace_vtd_inv_desc("iotlb", inv_desc.hi, inv_desc.lo);
        if (!vtd_process_iotlb_desc(s, &inv_desc)) {
            return false;
        }
        break;

    /*
     * TODO: the entity of below two cases will be implemented in future series.
     * To make guest (which integrates scalable mode support patch set in
     * iommu driver) work, just return true is enough so far.
     */
    case VTD_INV_DESC_PC:
        break;

    case VTD_INV_DESC_PIOTLB:
        break;

    case VTD_INV_DESC_WAIT:
        trace_vtd_inv_desc("wait", inv_desc.hi, inv_desc.lo);
        if (!vtd_process_wait_desc(s, &inv_desc)) {
            return false;
        }
        break;

    case VTD_INV_DESC_IEC:
        trace_vtd_inv_desc("iec", inv_desc.hi, inv_desc.lo);
        if (!vtd_process_inv_iec_desc(s, &inv_desc)) {
            return false;
        }
        break;

    case VTD_INV_DESC_DEVICE:
        trace_vtd_inv_desc("device", inv_desc.hi, inv_desc.lo);
        if (!vtd_process_device_iotlb_desc(s, &inv_desc)) {
            return false;
        }
        break;

    default:
        error_report_once("%s: invalid inv desc: hi=%"PRIx64", lo=%"PRIx64
                          " (unknown type)", __func__, inv_desc.hi,
                          inv_desc.lo);
        return false;
    }
    s->iq_head++;
    if (s->iq_head == s->iq_size) {
        s->iq_head = 0;
    }
    return true;
}

/* Try to fetch and process more Invalidation Descriptors */
static void vtd_fetch_inv_desc(IntelIOMMUState *s)
{
    trace_vtd_inv_qi_fetch();

    if (s->iq_tail >= s->iq_size) {
        /* Detects an invalid Tail pointer */
        error_report_once("%s: detected invalid QI tail "
                          "(tail=0x%x, size=0x%x)",
                          __func__, s->iq_tail, s->iq_size);
        vtd_handle_inv_queue_error(s);
        return;
    }
    while (s->iq_head != s->iq_tail) {
        if (!vtd_process_inv_desc(s)) {
            /* Invalidation Queue Errors */
            vtd_handle_inv_queue_error(s);
            break;
        }
        /* Must update the IQH_REG in time */
        vtd_set_quad_raw(s, DMAR_IQH_REG,
                         (((uint64_t)(s->iq_head)) << VTD_IQH_QH_SHIFT) &
                         VTD_IQH_QH_MASK);
    }
}

/* Handle write to Invalidation Queue Tail Register */
static void vtd_handle_iqt_write(IntelIOMMUState *s)
{
    uint64_t val = vtd_get_quad_raw(s, DMAR_IQT_REG);

    if (s->iq_dw && (val & VTD_IQT_QT_256_RSV_BIT)) {
        error_report_once("%s: RSV bit is set: val=0x%"PRIx64,
                          __func__, val);
        return;
    }
    s->iq_tail = VTD_IQT_QT(s->iq_dw, val);
    trace_vtd_inv_qi_tail(s->iq_tail);

    if (s->qi_enabled && !(vtd_get_long_raw(s, DMAR_FSTS_REG) & VTD_FSTS_IQE)) {
        /* Process Invalidation Queue here */
        vtd_fetch_inv_desc(s);
    }
}

static void vtd_handle_fsts_write(IntelIOMMUState *s)
{
    uint32_t fsts_reg = vtd_get_long_raw(s, DMAR_FSTS_REG);
    uint32_t fectl_reg = vtd_get_long_raw(s, DMAR_FECTL_REG);
    uint32_t status_fields = VTD_FSTS_PFO | VTD_FSTS_PPF | VTD_FSTS_IQE;

    if ((fectl_reg & VTD_FECTL_IP) && !(fsts_reg & status_fields)) {
        vtd_set_clear_mask_long(s, DMAR_FECTL_REG, VTD_FECTL_IP, 0);
        trace_vtd_fsts_clear_ip();
    }
    /* FIXME: when IQE is Clear, should we try to fetch some Invalidation
     * Descriptors if there are any when Queued Invalidation is enabled?
     */
}

static void vtd_handle_fectl_write(IntelIOMMUState *s)
{
    uint32_t fectl_reg;
    /* FIXME: when software clears the IM field, check the IP field. But do we
     * need to compare the old value and the new value to conclude that
     * software clears the IM field? Or just check if the IM field is zero?
     */
    fectl_reg = vtd_get_long_raw(s, DMAR_FECTL_REG);

    trace_vtd_reg_write_fectl(fectl_reg);

    if ((fectl_reg & VTD_FECTL_IP) && !(fectl_reg & VTD_FECTL_IM)) {
        vtd_generate_interrupt(s, DMAR_FEADDR_REG, DMAR_FEDATA_REG);
        vtd_set_clear_mask_long(s, DMAR_FECTL_REG, VTD_FECTL_IP, 0);
    }
}

static void vtd_handle_ics_write(IntelIOMMUState *s)
{
    uint32_t ics_reg = vtd_get_long_raw(s, DMAR_ICS_REG);
    uint32_t iectl_reg = vtd_get_long_raw(s, DMAR_IECTL_REG);

    if ((iectl_reg & VTD_IECTL_IP) && !(ics_reg & VTD_ICS_IWC)) {
        trace_vtd_reg_ics_clear_ip();
        vtd_set_clear_mask_long(s, DMAR_IECTL_REG, VTD_IECTL_IP, 0);
    }
}

static void vtd_handle_iectl_write(IntelIOMMUState *s)
{
    uint32_t iectl_reg;
    /* FIXME: when software clears the IM field, check the IP field. But do we
     * need to compare the old value and the new value to conclude that
     * software clears the IM field? Or just check if the IM field is zero?
     */
    iectl_reg = vtd_get_long_raw(s, DMAR_IECTL_REG);

    trace_vtd_reg_write_iectl(iectl_reg);

    if ((iectl_reg & VTD_IECTL_IP) && !(iectl_reg & VTD_IECTL_IM)) {
        vtd_generate_interrupt(s, DMAR_IEADDR_REG, DMAR_IEDATA_REG);
        vtd_set_clear_mask_long(s, DMAR_IECTL_REG, VTD_IECTL_IP, 0);
    }
}

static uint64_t vtd_mem_read(void *opaque, hwaddr addr, unsigned size)
{
    IntelIOMMUState *s = opaque;
    uint64_t val;

    trace_vtd_reg_read(addr, size);

    if (addr + size > DMAR_REG_SIZE) {
        error_report_once("%s: MMIO over range: addr=0x%" PRIx64
                          " size=0x%u", __func__, addr, size);
        return (uint64_t)-1;
    }

    switch (addr) {
    /* Root Table Address Register, 64-bit */
    case DMAR_RTADDR_REG:
        if (size == 4) {
            val = s->root & ((1ULL << 32) - 1);
        } else {
            val = s->root;
        }
        break;

    case DMAR_RTADDR_REG_HI:
        assert(size == 4);
        val = s->root >> 32;
        break;

    /* Invalidation Queue Address Register, 64-bit */
    case DMAR_IQA_REG:
        val = s->iq | (vtd_get_quad(s, DMAR_IQA_REG) & VTD_IQA_QS);
        if (size == 4) {
            val = val & ((1ULL << 32) - 1);
        }
        break;

    case DMAR_IQA_REG_HI:
        assert(size == 4);
        val = s->iq >> 32;
        break;

    default:
        if (size == 4) {
            val = vtd_get_long(s, addr);
        } else {
            val = vtd_get_quad(s, addr);
        }
    }

    return val;
}

static void vtd_mem_write(void *opaque, hwaddr addr,
                          uint64_t val, unsigned size)
{
    IntelIOMMUState *s = opaque;

    trace_vtd_reg_write(addr, size, val);

    if (addr + size > DMAR_REG_SIZE) {
        error_report_once("%s: MMIO over range: addr=0x%" PRIx64
                          " size=0x%u", __func__, addr, size);
        return;
    }

    switch (addr) {
    /* Global Command Register, 32-bit */
    case DMAR_GCMD_REG:
        vtd_set_long(s, addr, val);
        vtd_handle_gcmd_write(s);
        break;

    /* Context Command Register, 64-bit */
    case DMAR_CCMD_REG:
        if (size == 4) {
            vtd_set_long(s, addr, val);
        } else {
            vtd_set_quad(s, addr, val);
            vtd_handle_ccmd_write(s);
        }
        break;

    case DMAR_CCMD_REG_HI:
        assert(size == 4);
        vtd_set_long(s, addr, val);
        vtd_handle_ccmd_write(s);
        break;

    /* IOTLB Invalidation Register, 64-bit */
    case DMAR_IOTLB_REG:
        if (size == 4) {
            vtd_set_long(s, addr, val);
        } else {
            vtd_set_quad(s, addr, val);
            vtd_handle_iotlb_write(s);
        }
        break;

    case DMAR_IOTLB_REG_HI:
        assert(size == 4);
        vtd_set_long(s, addr, val);
        vtd_handle_iotlb_write(s);
        break;

    /* Invalidate Address Register, 64-bit */
    case DMAR_IVA_REG:
        if (size == 4) {
            vtd_set_long(s, addr, val);
        } else {
            vtd_set_quad(s, addr, val);
        }
        break;

    case DMAR_IVA_REG_HI:
        assert(size == 4);
        vtd_set_long(s, addr, val);
        break;

    /* Fault Status Register, 32-bit */
    case DMAR_FSTS_REG:
        assert(size == 4);
        vtd_set_long(s, addr, val);
        vtd_handle_fsts_write(s);
        break;

    /* Fault Event Control Register, 32-bit */
    case DMAR_FECTL_REG:
        assert(size == 4);
        vtd_set_long(s, addr, val);
        vtd_handle_fectl_write(s);
        break;

    /* Fault Event Data Register, 32-bit */
    case DMAR_FEDATA_REG:
        assert(size == 4);
        vtd_set_long(s, addr, val);
        break;

    /* Fault Event Address Register, 32-bit */
    case DMAR_FEADDR_REG:
        if (size == 4) {
            vtd_set_long(s, addr, val);
        } else {
            /*
             * While the register is 32-bit only, some guests (Xen...) write to
             * it with 64-bit.
             */
            vtd_set_quad(s, addr, val);
        }
        break;

    /* Fault Event Upper Address Register, 32-bit */
    case DMAR_FEUADDR_REG:
        assert(size == 4);
        vtd_set_long(s, addr, val);
        break;

    /* Protected Memory Enable Register, 32-bit */
    case DMAR_PMEN_REG:
        assert(size == 4);
        vtd_set_long(s, addr, val);
        break;

    /* Root Table Address Register, 64-bit */
    case DMAR_RTADDR_REG:
        if (size == 4) {
            vtd_set_long(s, addr, val);
        } else {
            vtd_set_quad(s, addr, val);
        }
        break;

    case DMAR_RTADDR_REG_HI:
        assert(size == 4);
        vtd_set_long(s, addr, val);
        break;

    /* Invalidation Queue Tail Register, 64-bit */
    case DMAR_IQT_REG:
        if (size == 4) {
            vtd_set_long(s, addr, val);
        } else {
            vtd_set_quad(s, addr, val);
        }
        vtd_handle_iqt_write(s);
        break;

    case DMAR_IQT_REG_HI:
        assert(size == 4);
        vtd_set_long(s, addr, val);
        /* 19:63 of IQT_REG is RsvdZ, do nothing here */
        break;

    /* Invalidation Queue Address Register, 64-bit */
    case DMAR_IQA_REG:
        if (size == 4) {
            vtd_set_long(s, addr, val);
        } else {
            vtd_set_quad(s, addr, val);
        }
        if (s->ecap & VTD_ECAP_SMTS &&
            val & VTD_IQA_DW_MASK) {
            s->iq_dw = true;
        } else {
            s->iq_dw = false;
        }
        break;

    case DMAR_IQA_REG_HI:
        assert(size == 4);
        vtd_set_long(s, addr, val);
        break;

    /* Invalidation Completion Status Register, 32-bit */
    case DMAR_ICS_REG:
        assert(size == 4);
        vtd_set_long(s, addr, val);
        vtd_handle_ics_write(s);
        break;

    /* Invalidation Event Control Register, 32-bit */
    case DMAR_IECTL_REG:
        assert(size == 4);
        vtd_set_long(s, addr, val);
        vtd_handle_iectl_write(s);
        break;

    /* Invalidation Event Data Register, 32-bit */
    case DMAR_IEDATA_REG:
        assert(size == 4);
        vtd_set_long(s, addr, val);
        break;

    /* Invalidation Event Address Register, 32-bit */
    case DMAR_IEADDR_REG:
        assert(size == 4);
        vtd_set_long(s, addr, val);
        break;

    /* Invalidation Event Upper Address Register, 32-bit */
    case DMAR_IEUADDR_REG:
        assert(size == 4);
        vtd_set_long(s, addr, val);
        break;

    /* Fault Recording Registers, 128-bit */
    case DMAR_FRCD_REG_0_0:
        if (size == 4) {
            vtd_set_long(s, addr, val);
        } else {
            vtd_set_quad(s, addr, val);
        }
        break;

    case DMAR_FRCD_REG_0_1:
        assert(size == 4);
        vtd_set_long(s, addr, val);
        break;

    case DMAR_FRCD_REG_0_2:
        if (size == 4) {
            vtd_set_long(s, addr, val);
        } else {
            vtd_set_quad(s, addr, val);
            /* May clear bit 127 (Fault), update PPF */
            vtd_update_fsts_ppf(s);
        }
        break;

    case DMAR_FRCD_REG_0_3:
        assert(size == 4);
        vtd_set_long(s, addr, val);
        /* May clear bit 127 (Fault), update PPF */
        vtd_update_fsts_ppf(s);
        break;

    case DMAR_IRTA_REG:
        if (size == 4) {
            vtd_set_long(s, addr, val);
        } else {
            vtd_set_quad(s, addr, val);
        }
        break;

    case DMAR_IRTA_REG_HI:
        assert(size == 4);
        vtd_set_long(s, addr, val);
        break;

    default:
        if (size == 4) {
            vtd_set_long(s, addr, val);
        } else {
            vtd_set_quad(s, addr, val);
        }
    }
}

static IOMMUTLBEntry vtd_iommu_translate(IOMMUMemoryRegion *iommu, hwaddr addr,
                                         IOMMUAccessFlags flag, int iommu_idx)
{
    VTDAddressSpace *vtd_as = container_of(iommu, VTDAddressSpace, iommu);
    IntelIOMMUState *s = vtd_as->iommu_state;
    IOMMUTLBEntry iotlb = {
        /* We'll fill in the rest later. */
        .target_as = &address_space_memory,
    };
    bool success;

    if (likely(s->dmar_enabled)) {
        success = vtd_do_iommu_translate(vtd_as, vtd_as->bus, vtd_as->devfn,
                                         addr, flag & IOMMU_WO, &iotlb);
    } else {
        /* DMAR disabled, passthrough, use 4k-page*/
        iotlb.iova = addr & VTD_PAGE_MASK_4K;
        iotlb.translated_addr = addr & VTD_PAGE_MASK_4K;
        iotlb.addr_mask = ~VTD_PAGE_MASK_4K;
        iotlb.perm = IOMMU_RW;
        success = true;
    }

    if (likely(success)) {
        trace_vtd_dmar_translate(pci_bus_num(vtd_as->bus),
                                 VTD_PCI_SLOT(vtd_as->devfn),
                                 VTD_PCI_FUNC(vtd_as->devfn),
                                 iotlb.iova, iotlb.translated_addr,
                                 iotlb.addr_mask);
    } else {
        error_report_once("%s: detected translation failure "
                          "(dev=%02x:%02x:%02x, iova=0x%" PRIx64 ")",
                          __func__, pci_bus_num(vtd_as->bus),
                          VTD_PCI_SLOT(vtd_as->devfn),
                          VTD_PCI_FUNC(vtd_as->devfn),
                          addr);
    }

    return iotlb;
}

static void vtd_iommu_notify_flag_changed(IOMMUMemoryRegion *iommu,
                                          IOMMUNotifierFlag old,
                                          IOMMUNotifierFlag new)
{
    VTDAddressSpace *vtd_as = container_of(iommu, VTDAddressSpace, iommu);
    IntelIOMMUState *s = vtd_as->iommu_state;

    if (!s->caching_mode && new & IOMMU_NOTIFIER_MAP) {
        vtd_panic_require_caching_mode();
    }

    /* Update per-address-space notifier flags */
    vtd_as->notifier_flags = new;

    if (old == IOMMU_NOTIFIER_NONE) {
        QLIST_INSERT_HEAD(&s->vtd_as_with_notifiers, vtd_as, next);
    } else if (new == IOMMU_NOTIFIER_NONE) {
        QLIST_REMOVE(vtd_as, next);
    }
}

static int vtd_post_load(void *opaque, int version_id)
{
    IntelIOMMUState *iommu = opaque;

    /*
     * Memory regions are dynamically turned on/off depending on
     * context entry configurations from the guest. After migration,
     * we need to make sure the memory regions are still correct.
     */
    vtd_switch_address_space_all(iommu);

    /*
     * We don't need to migrate the root_scalable because we can
     * simply do the calculation after the loading is complete.  We
     * can actually do similar things with root, dmar_enabled, etc.
     * however since we've had them already so we'd better keep them
     * for compatibility of migration.
     */
    vtd_update_scalable_state(iommu);

    return 0;
}

static const VMStateDescription vtd_vmstate = {
    .name = "iommu-intel",
    .version_id = 1,
    .minimum_version_id = 1,
    .priority = MIG_PRI_IOMMU,
    .post_load = vtd_post_load,
    .fields = (VMStateField[]) {
        VMSTATE_UINT64(root, IntelIOMMUState),
        VMSTATE_UINT64(intr_root, IntelIOMMUState),
        VMSTATE_UINT64(iq, IntelIOMMUState),
        VMSTATE_UINT32(intr_size, IntelIOMMUState),
        VMSTATE_UINT16(iq_head, IntelIOMMUState),
        VMSTATE_UINT16(iq_tail, IntelIOMMUState),
        VMSTATE_UINT16(iq_size, IntelIOMMUState),
        VMSTATE_UINT16(next_frcd_reg, IntelIOMMUState),
        VMSTATE_UINT8_ARRAY(csr, IntelIOMMUState, DMAR_REG_SIZE),
        VMSTATE_UINT8(iq_last_desc_type, IntelIOMMUState),
        VMSTATE_UNUSED(1),      /* bool root_extended is obsolete by VT-d */
        VMSTATE_BOOL(dmar_enabled, IntelIOMMUState),
        VMSTATE_BOOL(qi_enabled, IntelIOMMUState),
        VMSTATE_BOOL(intr_enabled, IntelIOMMUState),
        VMSTATE_BOOL(intr_eime, IntelIOMMUState),
        VMSTATE_END_OF_LIST()
    }
};

static const MemoryRegionOps vtd_mem_ops = {
    .read = vtd_mem_read,
    .write = vtd_mem_write,
    .endianness = DEVICE_LITTLE_ENDIAN,
    .impl = {
        .min_access_size = 4,
        .max_access_size = 8,
    },
    .valid = {
        .min_access_size = 4,
        .max_access_size = 8,
    },
};

static Property vtd_properties[] = {
    DEFINE_PROP_UINT32("version", IntelIOMMUState, version, 0),
    DEFINE_PROP_ON_OFF_AUTO("eim", IntelIOMMUState, intr_eim,
                            ON_OFF_AUTO_AUTO),
    DEFINE_PROP_BOOL("x-buggy-eim", IntelIOMMUState, buggy_eim, false),
    DEFINE_PROP_UINT8("aw-bits", IntelIOMMUState, aw_bits,
                      VTD_HOST_ADDRESS_WIDTH),
    DEFINE_PROP_BOOL("caching-mode", IntelIOMMUState, caching_mode, FALSE),
    DEFINE_PROP_BOOL("x-scalable-mode", IntelIOMMUState, scalable_mode, FALSE),
    DEFINE_PROP_BOOL("dma-drain", IntelIOMMUState, dma_drain, true),
    DEFINE_PROP_END_OF_LIST(),
};

/* Read IRTE entry with specific index */
static int vtd_irte_get(IntelIOMMUState *iommu, uint16_t index,
                        VTD_IR_TableEntry *entry, uint16_t sid)
{
    static const uint16_t vtd_svt_mask[VTD_SQ_MAX] = \
        {0xffff, 0xfffb, 0xfff9, 0xfff8};
    dma_addr_t addr = 0x00;
    uint16_t mask, source_id;
    uint8_t bus, bus_max, bus_min;

    addr = iommu->intr_root + index * sizeof(*entry);
    if (dma_memory_read(&address_space_memory, addr, entry,
                        sizeof(*entry))) {
        error_report_once("%s: read failed: ind=0x%x addr=0x%" PRIx64,
                          __func__, index, addr);
        return -VTD_FR_IR_ROOT_INVAL;
    }

    trace_vtd_ir_irte_get(index, le64_to_cpu(entry->data[1]),
                          le64_to_cpu(entry->data[0]));

    if (!entry->irte.present) {
        error_report_once("%s: detected non-present IRTE "
                          "(index=%u, high=0x%" PRIx64 ", low=0x%" PRIx64 ")",
                          __func__, index, le64_to_cpu(entry->data[1]),
                          le64_to_cpu(entry->data[0]));
        return -VTD_FR_IR_ENTRY_P;
    }

    if (entry->irte.__reserved_0 || entry->irte.__reserved_1 ||
        entry->irte.__reserved_2) {
        error_report_once("%s: detected non-zero reserved IRTE "
                          "(index=%u, high=0x%" PRIx64 ", low=0x%" PRIx64 ")",
                          __func__, index, le64_to_cpu(entry->data[1]),
                          le64_to_cpu(entry->data[0]));
        return -VTD_FR_IR_IRTE_RSVD;
    }

    if (sid != X86_IOMMU_SID_INVALID) {
        /* Validate IRTE SID */
        source_id = le32_to_cpu(entry->irte.source_id);
        switch (entry->irte.sid_vtype) {
        case VTD_SVT_NONE:
            break;

        case VTD_SVT_ALL:
            mask = vtd_svt_mask[entry->irte.sid_q];
            if ((source_id & mask) != (sid & mask)) {
                error_report_once("%s: invalid IRTE SID "
                                  "(index=%u, sid=%u, source_id=%u)",
                                  __func__, index, sid, source_id);
                return -VTD_FR_IR_SID_ERR;
            }
            break;

        case VTD_SVT_BUS:
            bus_max = source_id >> 8;
            bus_min = source_id & 0xff;
            bus = sid >> 8;
            if (bus > bus_max || bus < bus_min) {
                error_report_once("%s: invalid SVT_BUS "
                                  "(index=%u, bus=%u, min=%u, max=%u)",
                                  __func__, index, bus, bus_min, bus_max);
                return -VTD_FR_IR_SID_ERR;
            }
            break;

        default:
            error_report_once("%s: detected invalid IRTE SVT "
                              "(index=%u, type=%d)", __func__,
                              index, entry->irte.sid_vtype);
            /* Take this as verification failure. */
            return -VTD_FR_IR_SID_ERR;
            break;
        }
    }

    return 0;
}

/* Fetch IRQ information of specific IR index */
static int vtd_remap_irq_get(IntelIOMMUState *iommu, uint16_t index,
                             X86IOMMUIrq *irq, uint16_t sid)
{
    VTD_IR_TableEntry irte = {};
    int ret = 0;

    ret = vtd_irte_get(iommu, index, &irte, sid);
    if (ret) {
        return ret;
    }

    irq->trigger_mode = irte.irte.trigger_mode;
    irq->vector = irte.irte.vector;
    irq->delivery_mode = irte.irte.delivery_mode;
    irq->dest = le32_to_cpu(irte.irte.dest_id);
    if (!iommu->intr_eime) {
#define  VTD_IR_APIC_DEST_MASK         (0xff00ULL)
#define  VTD_IR_APIC_DEST_SHIFT        (8)
        irq->dest = (irq->dest & VTD_IR_APIC_DEST_MASK) >>
            VTD_IR_APIC_DEST_SHIFT;
    }
    irq->dest_mode = irte.irte.dest_mode;
    irq->redir_hint = irte.irte.redir_hint;

    trace_vtd_ir_remap(index, irq->trigger_mode, irq->vector,
                       irq->delivery_mode, irq->dest, irq->dest_mode);

    return 0;
}

/* Interrupt remapping for MSI/MSI-X entry */
static int vtd_interrupt_remap_msi(IntelIOMMUState *iommu,
                                   MSIMessage *origin,
                                   MSIMessage *translated,
                                   uint16_t sid)
{
    int ret = 0;
    VTD_IR_MSIAddress addr;
    uint16_t index;
    X86IOMMUIrq irq = {};

    assert(origin && translated);

    trace_vtd_ir_remap_msi_req(origin->address, origin->data);

    if (!iommu || !iommu->intr_enabled) {
        memcpy(translated, origin, sizeof(*origin));
        goto out;
    }

    if (origin->address & VTD_MSI_ADDR_HI_MASK) {
        error_report_once("%s: MSI address high 32 bits non-zero detected: "
                          "address=0x%" PRIx64, __func__, origin->address);
        return -VTD_FR_IR_REQ_RSVD;
    }

    addr.data = origin->address & VTD_MSI_ADDR_LO_MASK;
    if (addr.addr.__head != 0xfee) {
        error_report_once("%s: MSI address low 32 bit invalid: 0x%" PRIx32,
                          __func__, addr.data);
        return -VTD_FR_IR_REQ_RSVD;
    }

    /* This is compatible mode. */
    if (addr.addr.int_mode != VTD_IR_INT_FORMAT_REMAP) {
        memcpy(translated, origin, sizeof(*origin));
        goto out;
    }

    index = addr.addr.index_h << 15 | le16_to_cpu(addr.addr.index_l);

#define  VTD_IR_MSI_DATA_SUBHANDLE       (0x0000ffff)
#define  VTD_IR_MSI_DATA_RESERVED        (0xffff0000)

    if (addr.addr.sub_valid) {
        /* See VT-d spec 5.1.2.2 and 5.1.3 on subhandle */
        index += origin->data & VTD_IR_MSI_DATA_SUBHANDLE;
    }

    ret = vtd_remap_irq_get(iommu, index, &irq, sid);
    if (ret) {
        return ret;
    }

    if (addr.addr.sub_valid) {
        trace_vtd_ir_remap_type("MSI");
        if (origin->data & VTD_IR_MSI_DATA_RESERVED) {
            error_report_once("%s: invalid IR MSI "
                              "(sid=%u, address=0x%" PRIx64
                              ", data=0x%" PRIx32 ")",
                              __func__, sid, origin->address, origin->data);
            return -VTD_FR_IR_REQ_RSVD;
        }
    } else {
        uint8_t vector = origin->data & 0xff;
        uint8_t trigger_mode = (origin->data >> MSI_DATA_TRIGGER_SHIFT) & 0x1;

        trace_vtd_ir_remap_type("IOAPIC");
        /* IOAPIC entry vector should be aligned with IRTE vector
         * (see vt-d spec 5.1.5.1). */
        if (vector != irq.vector) {
            trace_vtd_warn_ir_vector(sid, index, vector, irq.vector);
        }

        /* The Trigger Mode field must match the Trigger Mode in the IRTE.
         * (see vt-d spec 5.1.5.1). */
        if (trigger_mode != irq.trigger_mode) {
            trace_vtd_warn_ir_trigger(sid, index, trigger_mode,
                                      irq.trigger_mode);
        }
    }

    /*
     * We'd better keep the last two bits, assuming that guest OS
     * might modify it. Keep it does not hurt after all.
     */
    irq.msi_addr_last_bits = addr.addr.__not_care;

    /* Translate X86IOMMUIrq to MSI message */
    x86_iommu_irq_to_msi_message(&irq, translated);

out:
    trace_vtd_ir_remap_msi(origin->address, origin->data,
                           translated->address, translated->data);
    return 0;
}

static int vtd_int_remap(X86IOMMUState *iommu, MSIMessage *src,
                         MSIMessage *dst, uint16_t sid)
{
    return vtd_interrupt_remap_msi(INTEL_IOMMU_DEVICE(iommu),
                                   src, dst, sid);
}

static MemTxResult vtd_mem_ir_read(void *opaque, hwaddr addr,
                                   uint64_t *data, unsigned size,
                                   MemTxAttrs attrs)
{
    return MEMTX_OK;
}

static MemTxResult vtd_mem_ir_write(void *opaque, hwaddr addr,
                                    uint64_t value, unsigned size,
                                    MemTxAttrs attrs)
{
    int ret = 0;
    MSIMessage from = {}, to = {};
    uint16_t sid = X86_IOMMU_SID_INVALID;

    from.address = (uint64_t) addr + VTD_INTERRUPT_ADDR_FIRST;
    from.data = (uint32_t) value;

    if (!attrs.unspecified) {
        /* We have explicit Source ID */
        sid = attrs.requester_id;
    }

    ret = vtd_interrupt_remap_msi(opaque, &from, &to, sid);
    if (ret) {
        /* TODO: report error */
        /* Drop this interrupt */
        return MEMTX_ERROR;
    }

    apic_get_class()->send_msi(&to);

    return MEMTX_OK;
}

static const MemoryRegionOps vtd_mem_ir_ops = {
    .read_with_attrs = vtd_mem_ir_read,
    .write_with_attrs = vtd_mem_ir_write,
    .endianness = DEVICE_LITTLE_ENDIAN,
    .impl = {
        .min_access_size = 4,
        .max_access_size = 4,
    },
    .valid = {
        .min_access_size = 4,
        .max_access_size = 4,
    },
};

VTDAddressSpace *vtd_find_add_as(IntelIOMMUState *s, PCIBus *bus, int devfn)
{
    uintptr_t key = (uintptr_t)bus;
    VTDBus *vtd_bus = g_hash_table_lookup(s->vtd_as_by_busptr, &key);
    VTDAddressSpace *vtd_dev_as;
    char name[128];

    if (!vtd_bus) {
        uintptr_t *new_key = g_malloc(sizeof(*new_key));
        *new_key = (uintptr_t)bus;
        /* No corresponding free() */
        vtd_bus = g_malloc0(sizeof(VTDBus) + sizeof(VTDAddressSpace *) * \
                            PCI_DEVFN_MAX);
        vtd_bus->bus = bus;
        g_hash_table_insert(s->vtd_as_by_busptr, new_key, vtd_bus);
    }

    vtd_dev_as = vtd_bus->dev_as[devfn];

    if (!vtd_dev_as) {
        snprintf(name, sizeof(name), "vtd-%02x.%x", PCI_SLOT(devfn),
                 PCI_FUNC(devfn));
        vtd_bus->dev_as[devfn] = vtd_dev_as = g_malloc0(sizeof(VTDAddressSpace));

        vtd_dev_as->bus = bus;
        vtd_dev_as->devfn = (uint8_t)devfn;
        vtd_dev_as->iommu_state = s;
        vtd_dev_as->context_cache_entry.context_cache_gen = 0;
        vtd_dev_as->iova_tree = iova_tree_new();

        memory_region_init(&vtd_dev_as->root, OBJECT(s), name, UINT64_MAX);
        address_space_init(&vtd_dev_as->as, &vtd_dev_as->root, "vtd-root");

        /*
         * Build the DMAR-disabled container with aliases to the
         * shared MRs.  Note that aliasing to a shared memory region
         * could help the memory API to detect same FlatViews so we
         * can have devices to share the same FlatView when DMAR is
         * disabled (either by not providing "intel_iommu=on" or with
         * "iommu=pt").  It will greatly reduce the total number of
         * FlatViews of the system hence VM runs faster.
         */
        memory_region_init_alias(&vtd_dev_as->nodmar, OBJECT(s),
                                 "vtd-nodmar", &s->mr_nodmar, 0,
                                 memory_region_size(&s->mr_nodmar));

        /*
         * Build the per-device DMAR-enabled container.
         *
         * TODO: currently we have per-device IOMMU memory region only
         * because we have per-device IOMMU notifiers for devices.  If
         * one day we can abstract the IOMMU notifiers out of the
         * memory regions then we can also share the same memory
         * region here just like what we've done above with the nodmar
         * region.
         */
        strcat(name, "-dmar");
        memory_region_init_iommu(&vtd_dev_as->iommu, sizeof(vtd_dev_as->iommu),
                                 TYPE_INTEL_IOMMU_MEMORY_REGION, OBJECT(s),
                                 name, UINT64_MAX);
        memory_region_init_alias(&vtd_dev_as->iommu_ir, OBJECT(s), "vtd-ir",
                                 &s->mr_ir, 0, memory_region_size(&s->mr_ir));
        memory_region_add_subregion_overlap(MEMORY_REGION(&vtd_dev_as->iommu),
                                            VTD_INTERRUPT_ADDR_FIRST,
                                            &vtd_dev_as->iommu_ir, 1);

        /*
         * Hook both the containers under the root container, we
         * switch between DMAR & noDMAR by enable/disable
         * corresponding sub-containers
         */
        memory_region_add_subregion_overlap(&vtd_dev_as->root, 0,
                                            MEMORY_REGION(&vtd_dev_as->iommu),
                                            0);
        memory_region_add_subregion_overlap(&vtd_dev_as->root, 0,
                                            &vtd_dev_as->nodmar, 0);

        vtd_switch_address_space(vtd_dev_as);
    }
    return vtd_dev_as;
}

static uint64_t get_naturally_aligned_size(uint64_t start,
                                           uint64_t size, int gaw)
{
    uint64_t max_mask = 1ULL << gaw;
    uint64_t alignment = start ? start & -start : max_mask;

    alignment = MIN(alignment, max_mask);
    size = MIN(size, max_mask);

    if (alignment <= size) {
        /* Increase the alignment of start */
        return alignment;
    } else {
        /* Find the largest page mask from size */
        return 1ULL << (63 - clz64(size));
    }
}

/* Unmap the whole range in the notifier's scope. */
static void vtd_address_space_unmap(VTDAddressSpace *as, IOMMUNotifier *n)
{
    hwaddr size, remain;
    hwaddr start = n->start;
    hwaddr end = n->end;
    IntelIOMMUState *s = as->iommu_state;
    DMAMap map;

    /*
     * Note: all the codes in this function has a assumption that IOVA
     * bits are no more than VTD_MGAW bits (which is restricted by
     * VT-d spec), otherwise we need to consider overflow of 64 bits.
     */

    if (end > VTD_ADDRESS_SIZE(s->aw_bits) - 1) {
        /*
         * Don't need to unmap regions that is bigger than the whole
         * VT-d supported address space size
         */
        end = VTD_ADDRESS_SIZE(s->aw_bits) - 1;
    }

    assert(start <= end);
    size = remain = end - start + 1;

    while (remain >= VTD_PAGE_SIZE) {
        IOMMUTLBEntry entry;
        uint64_t mask = get_naturally_aligned_size(start, remain, s->aw_bits);

        assert(mask);

        entry.iova = start;
        entry.addr_mask = mask - 1;
        entry.target_as = &address_space_memory;
        entry.perm = IOMMU_NONE;
        /* This field is meaningless for unmap */
        entry.translated_addr = 0;

        memory_region_notify_one(n, &entry);

        start += mask;
        remain -= mask;
    }

    assert(!remain);

    trace_vtd_as_unmap_whole(pci_bus_num(as->bus),
                             VTD_PCI_SLOT(as->devfn),
                             VTD_PCI_FUNC(as->devfn),
                             n->start, size);

    map.iova = n->start;
    map.size = size;
    iova_tree_remove(as->iova_tree, &map);
}

static void vtd_address_space_unmap_all(IntelIOMMUState *s)
{
    VTDAddressSpace *vtd_as;
    IOMMUNotifier *n;

    QLIST_FOREACH(vtd_as, &s->vtd_as_with_notifiers, next) {
        IOMMU_NOTIFIER_FOREACH(n, &vtd_as->iommu) {
            vtd_address_space_unmap(vtd_as, n);
        }
    }
}

static void vtd_address_space_refresh_all(IntelIOMMUState *s)
{
    vtd_address_space_unmap_all(s);
    vtd_switch_address_space_all(s);
}

static int vtd_replay_hook(IOMMUTLBEntry *entry, void *private)
{
    memory_region_notify_one((IOMMUNotifier *)private, entry);
    return 0;
}

static void vtd_iommu_replay(IOMMUMemoryRegion *iommu_mr, IOMMUNotifier *n)
{
    VTDAddressSpace *vtd_as = container_of(iommu_mr, VTDAddressSpace, iommu);
    IntelIOMMUState *s = vtd_as->iommu_state;
    uint8_t bus_n = pci_bus_num(vtd_as->bus);
    VTDContextEntry ce;

    /*
     * The replay can be triggered by either a invalidation or a newly
     * created entry. No matter what, we release existing mappings
     * (it means flushing caches for UNMAP-only registers).
     */
    vtd_address_space_unmap(vtd_as, n);

    if (vtd_dev_to_context_entry(s, bus_n, vtd_as->devfn, &ce) == 0) {
        trace_vtd_replay_ce_valid(s->root_scalable ? "scalable mode" :
                                  "legacy mode",
                                  bus_n, PCI_SLOT(vtd_as->devfn),
                                  PCI_FUNC(vtd_as->devfn),
                                  vtd_get_domain_id(s, &ce),
                                  ce.hi, ce.lo);
        if (vtd_as_has_map_notifier(vtd_as)) {
            /* This is required only for MAP typed notifiers */
            vtd_page_walk_info info = {
                .hook_fn = vtd_replay_hook,
                .private = (void *)n,
                .notify_unmap = false,
                .aw = s->aw_bits,
                .as = vtd_as,
                .domain_id = vtd_get_domain_id(s, &ce),
            };

            vtd_page_walk(s, &ce, 0, ~0ULL, &info);
        }
    } else {
        trace_vtd_replay_ce_invalid(bus_n, PCI_SLOT(vtd_as->devfn),
                                    PCI_FUNC(vtd_as->devfn));
    }

    return;
}

/* Do the initialization. It will also be called when reset, so pay
 * attention when adding new initialization stuff.
 */
static void vtd_init(IntelIOMMUState *s)
{
    X86IOMMUState *x86_iommu = X86_IOMMU_DEVICE(s);

    memset(s->csr, 0, DMAR_REG_SIZE);
    memset(s->wmask, 0, DMAR_REG_SIZE);
    memset(s->w1cmask, 0, DMAR_REG_SIZE);
    memset(s->womask, 0, DMAR_REG_SIZE);

    s->root = 0;
    s->root_scalable = false;
    s->dmar_enabled = false;
    s->intr_enabled = false;
    s->iq_head = 0;
    s->iq_tail = 0;
    s->iq = 0;
    s->iq_size = 0;
    s->qi_enabled = false;
    s->iq_last_desc_type = VTD_INV_DESC_NONE;
    s->iq_dw = false;
    s->next_frcd_reg = 0;
    s->cap = VTD_CAP_FRO | VTD_CAP_NFR | VTD_CAP_ND |
             VTD_CAP_MAMV | VTD_CAP_PSI | VTD_CAP_SLLPS |
             VTD_CAP_SAGAW_39bit | VTD_CAP_MGAW(s->aw_bits);
    if (s->dma_drain) {
        s->cap |= VTD_CAP_DRAIN;
    }
    if (s->aw_bits == VTD_HOST_AW_48BIT) {
        s->cap |= VTD_CAP_SAGAW_48bit;
    }
    s->ecap = VTD_ECAP_QI | VTD_ECAP_IRO;

    /*
     * Rsvd field masks for spte
     */
    vtd_paging_entry_rsvd_field[0] = ~0ULL;
    vtd_paging_entry_rsvd_field[1] = VTD_SPTE_PAGE_L1_RSVD_MASK(s->aw_bits);
    vtd_paging_entry_rsvd_field[2] = VTD_SPTE_PAGE_L2_RSVD_MASK(s->aw_bits);
    vtd_paging_entry_rsvd_field[3] = VTD_SPTE_PAGE_L3_RSVD_MASK(s->aw_bits);
    vtd_paging_entry_rsvd_field[4] = VTD_SPTE_PAGE_L4_RSVD_MASK(s->aw_bits);
    vtd_paging_entry_rsvd_field[5] = VTD_SPTE_LPAGE_L1_RSVD_MASK(s->aw_bits);
    vtd_paging_entry_rsvd_field[6] = VTD_SPTE_LPAGE_L2_RSVD_MASK(s->aw_bits);
    vtd_paging_entry_rsvd_field[7] = VTD_SPTE_LPAGE_L3_RSVD_MASK(s->aw_bits);
    vtd_paging_entry_rsvd_field[8] = VTD_SPTE_LPAGE_L4_RSVD_MASK(s->aw_bits);

    if (x86_iommu_ir_supported(x86_iommu)) {
        s->ecap |= VTD_ECAP_IR | VTD_ECAP_MHMV;
        if (s->intr_eim == ON_OFF_AUTO_ON) {
            s->ecap |= VTD_ECAP_EIM;
        }
        assert(s->intr_eim != ON_OFF_AUTO_AUTO);
    }

    if (x86_iommu->dt_supported) {
        s->ecap |= VTD_ECAP_DT;
    }

    if (x86_iommu->pt_supported) {
        s->ecap |= VTD_ECAP_PT;
    }

    if (s->caching_mode) {
        s->cap |= VTD_CAP_CM;
    }

    /* TODO: read cap/ecap from host to decide which cap to be exposed. */
    if (s->scalable_mode) {
        s->ecap |= VTD_ECAP_SMTS | VTD_ECAP_SRS | VTD_ECAP_SLTS;
    }

    vtd_reset_caches(s);

    /* Define registers with default values and bit semantics */
    vtd_define_long(s, DMAR_VER_REG, 0x10UL, 0, 0);
    vtd_define_quad(s, DMAR_CAP_REG, s->cap, 0, 0);
    vtd_define_quad(s, DMAR_ECAP_REG, s->ecap, 0, 0);
    vtd_define_long(s, DMAR_GCMD_REG, 0, 0xff800000UL, 0);
    vtd_define_long_wo(s, DMAR_GCMD_REG, 0xff800000UL);
    vtd_define_long(s, DMAR_GSTS_REG, 0, 0, 0);
    vtd_define_quad(s, DMAR_RTADDR_REG, 0, 0xfffffffffffffc00ULL, 0);
    vtd_define_quad(s, DMAR_CCMD_REG, 0, 0xe0000003ffffffffULL, 0);
    vtd_define_quad_wo(s, DMAR_CCMD_REG, 0x3ffff0000ULL);

    /* Advanced Fault Logging not supported */
    vtd_define_long(s, DMAR_FSTS_REG, 0, 0, 0x11UL);
    vtd_define_long(s, DMAR_FECTL_REG, 0x80000000UL, 0x80000000UL, 0);
    vtd_define_long(s, DMAR_FEDATA_REG, 0, 0x0000ffffUL, 0);
    vtd_define_long(s, DMAR_FEADDR_REG, 0, 0xfffffffcUL, 0);

    /* Treated as RsvdZ when EIM in ECAP_REG is not supported
     * vtd_define_long(s, DMAR_FEUADDR_REG, 0, 0xffffffffUL, 0);
     */
    vtd_define_long(s, DMAR_FEUADDR_REG, 0, 0, 0);

    /* Treated as RO for implementations that PLMR and PHMR fields reported
     * as Clear in the CAP_REG.
     * vtd_define_long(s, DMAR_PMEN_REG, 0, 0x80000000UL, 0);
     */
    vtd_define_long(s, DMAR_PMEN_REG, 0, 0, 0);

    vtd_define_quad(s, DMAR_IQH_REG, 0, 0, 0);
    vtd_define_quad(s, DMAR_IQT_REG, 0, 0x7fff0ULL, 0);
    vtd_define_quad(s, DMAR_IQA_REG, 0, 0xfffffffffffff807ULL, 0);
    vtd_define_long(s, DMAR_ICS_REG, 0, 0, 0x1UL);
    vtd_define_long(s, DMAR_IECTL_REG, 0x80000000UL, 0x80000000UL, 0);
    vtd_define_long(s, DMAR_IEDATA_REG, 0, 0xffffffffUL, 0);
    vtd_define_long(s, DMAR_IEADDR_REG, 0, 0xfffffffcUL, 0);
    /* Treadted as RsvdZ when EIM in ECAP_REG is not supported */
    vtd_define_long(s, DMAR_IEUADDR_REG, 0, 0, 0);

    /* IOTLB registers */
    vtd_define_quad(s, DMAR_IOTLB_REG, 0, 0Xb003ffff00000000ULL, 0);
    vtd_define_quad(s, DMAR_IVA_REG, 0, 0xfffffffffffff07fULL, 0);
    vtd_define_quad_wo(s, DMAR_IVA_REG, 0xfffffffffffff07fULL);

    /* Fault Recording Registers, 128-bit */
    vtd_define_quad(s, DMAR_FRCD_REG_0_0, 0, 0, 0);
    vtd_define_quad(s, DMAR_FRCD_REG_0_2, 0, 0, 0x8000000000000000ULL);

    /*
     * Interrupt remapping registers.
     */
    vtd_define_quad(s, DMAR_IRTA_REG, 0, 0xfffffffffffff80fULL, 0);
}

/* Should not reset address_spaces when reset because devices will still use
 * the address space they got at first (won't ask the bus again).
 */
static void vtd_reset(DeviceState *dev)
{
    IntelIOMMUState *s = INTEL_IOMMU_DEVICE(dev);

    vtd_init(s);
    vtd_address_space_refresh_all(s);
}

static AddressSpace *vtd_host_dma_iommu(PCIBus *bus, void *opaque, int devfn)
{
    IntelIOMMUState *s = opaque;
    VTDAddressSpace *vtd_as;

    assert(0 <= devfn && devfn < PCI_DEVFN_MAX);

    vtd_as = vtd_find_add_as(s, bus, devfn);
    return &vtd_as->as;
}

static bool vtd_decide_config(IntelIOMMUState *s, Error **errp)
{
    X86IOMMUState *x86_iommu = X86_IOMMU_DEVICE(s);

    if (s->intr_eim == ON_OFF_AUTO_ON && !x86_iommu_ir_supported(x86_iommu)) {
        error_setg(errp, "eim=on cannot be selected without intremap=on");
        return false;
    }

    if (s->intr_eim == ON_OFF_AUTO_AUTO) {
        s->intr_eim = (kvm_irqchip_in_kernel() || s->buggy_eim)
                      && x86_iommu_ir_supported(x86_iommu) ?
                                              ON_OFF_AUTO_ON : ON_OFF_AUTO_OFF;
    }
    if (s->intr_eim == ON_OFF_AUTO_ON && !s->buggy_eim) {
        if (!kvm_irqchip_in_kernel()) {
            error_setg(errp, "eim=on requires accel=kvm,kernel-irqchip=split");
            return false;
        }
        if (!kvm_enable_x2apic()) {
            error_setg(errp, "eim=on requires support on the KVM side"
                             "(X2APIC_API, first shipped in v4.7)");
            return false;
        }
    }

    /* Currently only address widths supported are 39 and 48 bits */
    if ((s->aw_bits != VTD_HOST_AW_39BIT) &&
        (s->aw_bits != VTD_HOST_AW_48BIT)) {
        error_setg(errp, "Supported values for x-aw-bits are: %d, %d",
                   VTD_HOST_AW_39BIT, VTD_HOST_AW_48BIT);
        return false;
    }

    if (s->scalable_mode && !s->dma_drain) {
        error_setg(errp, "Need to set dma_drain for scalable mode");
        return false;
    }

    return true;
}

static int vtd_machine_done_notify_one(Object *child, void *unused)
{
    IntelIOMMUState *iommu = INTEL_IOMMU_DEVICE(x86_iommu_get_default());

    /*
     * We hard-coded here because vfio-pci is the only special case
     * here.  Let's be more elegant in the future when we can, but so
     * far there seems to be no better way.
     */
    if (object_dynamic_cast(child, "vfio-pci") && !iommu->caching_mode) {
        vtd_panic_require_caching_mode();
    }

    return 0;
}

static void vtd_machine_done_hook(Notifier *notifier, void *unused)
{
    object_child_foreach_recursive(object_get_root(),
                                   vtd_machine_done_notify_one, NULL);
}

static Notifier vtd_machine_done_notify = {
    .notify = vtd_machine_done_hook,
};

static void vtd_realize(DeviceState *dev, Error **errp)
{
    MachineState *ms = MACHINE(qdev_get_machine());
    PCMachineState *pcms = PC_MACHINE(ms);
    PCIBus *bus = pcms->bus;
    IntelIOMMUState *s = INTEL_IOMMU_DEVICE(dev);
    X86IOMMUState *x86_iommu = X86_IOMMU_DEVICE(dev);

    x86_iommu->type = TYPE_INTEL;

    if (!vtd_decide_config(s, errp)) {
        return;
    }

    QLIST_INIT(&s->vtd_as_with_notifiers);
    qemu_mutex_init(&s->iommu_lock);
    memset(s->vtd_as_by_bus_num, 0, sizeof(s->vtd_as_by_bus_num));
    memory_region_init_io(&s->csrmem, OBJECT(s), &vtd_mem_ops, s,
                          "intel_iommu", DMAR_REG_SIZE);

    /* Create the shared memory regions by all devices */
    memory_region_init(&s->mr_nodmar, OBJECT(s), "vtd-nodmar",
                       UINT64_MAX);
    memory_region_init_io(&s->mr_ir, OBJECT(s), &vtd_mem_ir_ops,
                          s, "vtd-ir", VTD_INTERRUPT_ADDR_SIZE);
    memory_region_init_alias(&s->mr_sys_alias, OBJECT(s),
                             "vtd-sys-alias", get_system_memory(), 0,
                             memory_region_size(get_system_memory()));
    memory_region_add_subregion_overlap(&s->mr_nodmar, 0,
                                        &s->mr_sys_alias, 0);
    memory_region_add_subregion_overlap(&s->mr_nodmar,
                                        VTD_INTERRUPT_ADDR_FIRST,
                                        &s->mr_ir, 1);

    sysbus_init_mmio(SYS_BUS_DEVICE(s), &s->csrmem);
    /* No corresponding destroy */
    s->iotlb = g_hash_table_new_full(vtd_uint64_hash, vtd_uint64_equal,
                                     g_free, g_free);
    s->vtd_as_by_busptr = g_hash_table_new_full(vtd_uint64_hash, vtd_uint64_equal,
                                              g_free, g_free);
    vtd_init(s);
    sysbus_mmio_map(SYS_BUS_DEVICE(s), 0, Q35_HOST_BRIDGE_IOMMU_ADDR);
    pci_setup_iommu(bus, vtd_host_dma_iommu, dev);
    /* Pseudo address space under root PCI bus. */
    pcms->ioapic_as = vtd_host_dma_iommu(bus, s, Q35_PSEUDO_DEVFN_IOAPIC);
    qemu_add_machine_init_done_notifier(&vtd_machine_done_notify);
}

static void vtd_class_init(ObjectClass *klass, void *data)
{
    DeviceClass *dc = DEVICE_CLASS(klass);
    X86IOMMUClass *x86_class = X86_IOMMU_CLASS(klass);

    dc->reset = vtd_reset;
    dc->vmsd = &vtd_vmstate;
    dc->props = vtd_properties;
    dc->hotpluggable = false;
    x86_class->realize = vtd_realize;
    x86_class->int_remap = vtd_int_remap;
    /* Supported by the pc-q35-* machine types */
    dc->user_creatable = true;
    set_bit(DEVICE_CATEGORY_MISC, dc->categories);
    dc->desc = "Intel IOMMU (VT-d) DMA Remapping device";
}

static const TypeInfo vtd_info = {
    .name          = TYPE_INTEL_IOMMU_DEVICE,
    .parent        = TYPE_X86_IOMMU_DEVICE,
    .instance_size = sizeof(IntelIOMMUState),
    .class_init    = vtd_class_init,
};

static void vtd_iommu_memory_region_class_init(ObjectClass *klass,
                                                     void *data)
{
    IOMMUMemoryRegionClass *imrc = IOMMU_MEMORY_REGION_CLASS(klass);

    imrc->translate = vtd_iommu_translate;
    imrc->notify_flag_changed = vtd_iommu_notify_flag_changed;
    imrc->replay = vtd_iommu_replay;
}

static const TypeInfo vtd_iommu_memory_region_info = {
    .parent = TYPE_IOMMU_MEMORY_REGION,
    .name = TYPE_INTEL_IOMMU_MEMORY_REGION,
    .class_init = vtd_iommu_memory_region_class_init,
};

static void vtd_register_types(void)
{
    type_register_static(&vtd_info);
    type_register_static(&vtd_iommu_memory_region_info);
}

type_init(vtd_register_types)