/*
 * Copyright (C) 2016 - ARM Ltd
 *
 * stage2 page table helpers
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * 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/>.
 */

#ifndef __ARM64_S2_PGTABLE_H_
#define __ARM64_S2_PGTABLE_H_

#include <linux/hugetlb.h>
#include <asm/pgtable.h>

/*
 * The hardware supports concatenation of up to 16 tables at stage2 entry level
 * and we use the feature whenever possible.
 *
 * Now, the minimum number of bits resolved at any level is (PAGE_SHIFT - 3).
 * On arm64, the smallest PAGE_SIZE supported is 4k, which means
 *             (PAGE_SHIFT - 3) > 4 holds for all page sizes.
 * This implies, the total number of page table levels at stage2 expected
 * by the hardware is actually the number of levels required for (KVM_PHYS_SHIFT - 4)
 * in normal translations(e.g, stage1), since we cannot have another level in
 * the range (KVM_PHYS_SHIFT, KVM_PHYS_SHIFT - 4).
 */
#define STAGE2_PGTABLE_LEVELS		ARM64_HW_PGTABLE_LEVELS(KVM_PHYS_SHIFT - 4)

/*
 * With all the supported VA_BITs and 40bit guest IPA, the following condition
 * is always true:
 *
 *       STAGE2_PGTABLE_LEVELS <= CONFIG_PGTABLE_LEVELS
 *
 * We base our stage-2 page table walker helpers on this assumption and
 * fall back to using the host version of the helper wherever possible.
 * i.e, if a particular level is not folded (e.g, PUD) at stage2, we fall back
 * to using the host version, since it is guaranteed it is not folded at host.
 *
 * If the condition breaks in the future, we can rearrange the host level
 * definitions and reuse them for stage2. Till then...
 */
#if STAGE2_PGTABLE_LEVELS > CONFIG_PGTABLE_LEVELS
#error "Unsupported combination of guest IPA and host VA_BITS."
#endif

/* S2_PGDIR_SHIFT is the size mapped by top-level stage2 entry */
#define S2_PGDIR_SHIFT			ARM64_HW_PGTABLE_LEVEL_SHIFT(4 - STAGE2_PGTABLE_LEVELS)
#define S2_PGDIR_SIZE			(1UL << S2_PGDIR_SHIFT)
#define S2_PGDIR_MASK			(~(S2_PGDIR_SIZE - 1))

/*
 * The number of PTRS across all concatenated stage2 tables given by the
 * number of bits resolved at the initial level.
 */
#define PTRS_PER_S2_PGD			(1 << (KVM_PHYS_SHIFT - S2_PGDIR_SHIFT))

/*
 * kvm_mmmu_cache_min_pages() is the number of pages required to install
 * a stage-2 translation. We pre-allocate the entry level page table at
 * the VM creation.
 */
#define kvm_mmu_cache_min_pages(kvm)	(STAGE2_PGTABLE_LEVELS - 1)

/* Stage2 PUD definitions when the level is present */
#define STAGE2_PGTABLE_HAS_PUD		(STAGE2_PGTABLE_LEVELS > 3)
#define S2_PUD_SHIFT			ARM64_HW_PGTABLE_LEVEL_SHIFT(1)
#define S2_PUD_SIZE			(1UL << S2_PUD_SHIFT)
#define S2_PUD_MASK			(~(S2_PUD_SIZE - 1))

static inline bool stage2_pgd_none(struct kvm *kvm, pgd_t pgd)
{
	if (STAGE2_PGTABLE_HAS_PUD)
		return pgd_none(pgd);
	else
		return 0;
}

static inline void stage2_pgd_clear(struct kvm *kvm, pgd_t *pgdp)
{
	if (STAGE2_PGTABLE_HAS_PUD)
		pgd_clear(pgdp);
}

static inline bool stage2_pgd_present(struct kvm *kvm, pgd_t pgd)
{
	if (STAGE2_PGTABLE_HAS_PUD)
		return pgd_present(pgd);
	else
		return 1;
}

static inline void stage2_pgd_populate(struct kvm *kvm, pgd_t *pgd, pud_t *pud)
{
	if (STAGE2_PGTABLE_HAS_PUD)
		pgd_populate(NULL, pgd, pud);
}

static inline pud_t *stage2_pud_offset(struct kvm *kvm,
				       pgd_t *pgd, unsigned long address)
{
	if (STAGE2_PGTABLE_HAS_PUD)
		return pud_offset(pgd, address);
	else
		return (pud_t *)pgd;
}

static inline void stage2_pud_free(struct kvm *kvm, pud_t *pud)
{
	if (STAGE2_PGTABLE_HAS_PUD)
		pud_free(NULL, pud);
}

static inline bool stage2_pud_table_empty(struct kvm *kvm, pud_t *pudp)
{
	if (STAGE2_PGTABLE_HAS_PUD)
		return kvm_page_empty(pudp);
	else
		return false;
}

static inline phys_addr_t
stage2_pud_addr_end(struct kvm *kvm, phys_addr_t addr, phys_addr_t end)
{
	if (STAGE2_PGTABLE_HAS_PUD) {
		phys_addr_t boundary = (addr + S2_PUD_SIZE) & S2_PUD_MASK;

		return (boundary - 1 < end - 1) ? boundary : end;
	} else {
		return end;
	}
}

/* Stage2 PMD definitions when the level is present */
#define STAGE2_PGTABLE_HAS_PMD		(STAGE2_PGTABLE_LEVELS > 2)
#define S2_PMD_SHIFT			ARM64_HW_PGTABLE_LEVEL_SHIFT(2)
#define S2_PMD_SIZE			(1UL << S2_PMD_SHIFT)
#define S2_PMD_MASK			(~(S2_PMD_SIZE - 1))

static inline bool stage2_pud_none(struct kvm *kvm, pud_t pud)
{
	if (STAGE2_PGTABLE_HAS_PMD)
		return pud_none(pud);
	else
		return 0;
}

static inline void stage2_pud_clear(struct kvm *kvm, pud_t *pud)
{
	if (STAGE2_PGTABLE_HAS_PMD)
		pud_clear(pud);
}

static inline bool stage2_pud_present(struct kvm *kvm, pud_t pud)
{
	if (STAGE2_PGTABLE_HAS_PMD)
		return pud_present(pud);
	else
		return 1;
}

static inline void stage2_pud_populate(struct kvm *kvm, pud_t *pud, pmd_t *pmd)
{
	if (STAGE2_PGTABLE_HAS_PMD)
		pud_populate(NULL, pud, pmd);
}

static inline pmd_t *stage2_pmd_offset(struct kvm *kvm,
				       pud_t *pud, unsigned long address)
{
	if (STAGE2_PGTABLE_HAS_PMD)
		return pmd_offset(pud, address);
	else
		return (pmd_t *)pud;
}

static inline void stage2_pmd_free(struct kvm *kvm, pmd_t *pmd)
{
	if (STAGE2_PGTABLE_HAS_PMD)
		pmd_free(NULL, pmd);
}

static inline bool stage2_pud_huge(struct kvm *kvm, pud_t pud)
{
	if (STAGE2_PGTABLE_HAS_PMD)
		return pud_huge(pud);
	else
		return 0;
}

static inline bool stage2_pmd_table_empty(struct kvm *kvm, pmd_t *pmdp)
{
	if (STAGE2_PGTABLE_HAS_PMD)
		return kvm_page_empty(pmdp);
	else
		return 0;
}

static inline phys_addr_t
stage2_pmd_addr_end(struct kvm *kvm, phys_addr_t addr, phys_addr_t end)
{
	if (STAGE2_PGTABLE_HAS_PMD) {
		phys_addr_t boundary = (addr + S2_PMD_SIZE) & S2_PMD_MASK;

		return (boundary - 1 < end - 1) ? boundary : end;
	} else {
		return end;
	}
}

static inline bool stage2_pte_table_empty(struct kvm *kvm, pte_t *ptep)
{
	return kvm_page_empty(ptep);
}

#define stage2_pgd_size(kvm)	(PTRS_PER_S2_PGD * sizeof(pgd_t))

static inline unsigned long stage2_pgd_index(struct kvm *kvm, phys_addr_t addr)
{
	return (((addr) >> S2_PGDIR_SHIFT) & (PTRS_PER_S2_PGD - 1));
}

static inline phys_addr_t
stage2_pgd_addr_end(struct kvm *kvm, phys_addr_t addr, phys_addr_t end)
{
	phys_addr_t boundary = (addr + S2_PGDIR_SIZE) & S2_PGDIR_MASK;

	return (boundary - 1 < end - 1) ? boundary : end;
}

#endif	/* __ARM64_S2_PGTABLE_H_ */