/*
 * iommufd container backend
 *
 * Copyright (C) 2023 Intel Corporation.
 * Copyright Red Hat, Inc. 2023
 *
 * Authors: Yi Liu <yi.l.liu@intel.com>
 *          Eric Auger <eric.auger@redhat.com>
 *
 * SPDX-License-Identifier: GPL-2.0-or-later
 */

#include "qemu/osdep.h"
#include <sys/ioctl.h>
#include <linux/vfio.h>
#include <linux/iommufd.h>

#include "hw/vfio/vfio-common.h"
#include "qemu/error-report.h"
#include "trace.h"
#include "qapi/error.h"
#include "sysemu/iommufd.h"
#include "hw/qdev-core.h"
#include "sysemu/reset.h"
#include "qemu/cutils.h"
#include "qemu/chardev_open.h"

static int iommufd_cdev_map(VFIOContainerBase *bcontainer, hwaddr iova,
                            ram_addr_t size, void *vaddr, bool readonly)
{
    VFIOIOMMUFDContainer *container =
        container_of(bcontainer, VFIOIOMMUFDContainer, bcontainer);

    return iommufd_backend_map_dma(container->be,
                                   container->ioas_id,
                                   iova, size, vaddr, readonly);
}

static int iommufd_cdev_unmap(VFIOContainerBase *bcontainer,
                              hwaddr iova, ram_addr_t size,
                              IOMMUTLBEntry *iotlb)
{
    VFIOIOMMUFDContainer *container =
        container_of(bcontainer, VFIOIOMMUFDContainer, bcontainer);

    /* TODO: Handle dma_unmap_bitmap with iotlb args (migration) */
    return iommufd_backend_unmap_dma(container->be,
                                     container->ioas_id, iova, size);
}

static int iommufd_cdev_kvm_device_add(VFIODevice *vbasedev, Error **errp)
{
    return vfio_kvm_device_add_fd(vbasedev->fd, errp);
}

static void iommufd_cdev_kvm_device_del(VFIODevice *vbasedev)
{
    Error *err = NULL;

    if (vfio_kvm_device_del_fd(vbasedev->fd, &err)) {
        error_report_err(err);
    }
}

static int iommufd_cdev_connect_and_bind(VFIODevice *vbasedev, Error **errp)
{
    IOMMUFDBackend *iommufd = vbasedev->iommufd;
    struct vfio_device_bind_iommufd bind = {
        .argsz = sizeof(bind),
        .flags = 0,
    };
    int ret;

    ret = iommufd_backend_connect(iommufd, errp);
    if (ret) {
        return ret;
    }

    /*
     * Add device to kvm-vfio to be prepared for the tracking
     * in KVM. Especially for some emulated devices, it requires
     * to have kvm information in the device open.
     */
    ret = iommufd_cdev_kvm_device_add(vbasedev, errp);
    if (ret) {
        goto err_kvm_device_add;
    }

    /* Bind device to iommufd */
    bind.iommufd = iommufd->fd;
    ret = ioctl(vbasedev->fd, VFIO_DEVICE_BIND_IOMMUFD, &bind);
    if (ret) {
        error_setg_errno(errp, errno, "error bind device fd=%d to iommufd=%d",
                         vbasedev->fd, bind.iommufd);
        goto err_bind;
    }

    vbasedev->devid = bind.out_devid;
    trace_iommufd_cdev_connect_and_bind(bind.iommufd, vbasedev->name,
                                        vbasedev->fd, vbasedev->devid);
    return ret;
err_bind:
    iommufd_cdev_kvm_device_del(vbasedev);
err_kvm_device_add:
    iommufd_backend_disconnect(iommufd);
    return ret;
}

static void iommufd_cdev_unbind_and_disconnect(VFIODevice *vbasedev)
{
    /* Unbind is automatically conducted when device fd is closed */
    iommufd_cdev_kvm_device_del(vbasedev);
    iommufd_backend_disconnect(vbasedev->iommufd);
}

static int iommufd_cdev_getfd(const char *sysfs_path, Error **errp)
{
    long int ret = -ENOTTY;
    char *path, *vfio_dev_path = NULL, *vfio_path = NULL;
    DIR *dir = NULL;
    struct dirent *dent;
    gchar *contents;
    struct stat st;
    gsize length;
    int major, minor;
    dev_t vfio_devt;

    path = g_strdup_printf("%s/vfio-dev", sysfs_path);
    if (stat(path, &st) < 0) {
        error_setg_errno(errp, errno, "no such host device");
        goto out_free_path;
    }

    dir = opendir(path);
    if (!dir) {
        error_setg_errno(errp, errno, "couldn't open directory %s", path);
        goto out_free_path;
    }

    while ((dent = readdir(dir))) {
        if (!strncmp(dent->d_name, "vfio", 4)) {
            vfio_dev_path = g_strdup_printf("%s/%s/dev", path, dent->d_name);
            break;
        }
    }

    if (!vfio_dev_path) {
        error_setg(errp, "failed to find vfio-dev/vfioX/dev");
        goto out_close_dir;
    }

    if (!g_file_get_contents(vfio_dev_path, &contents, &length, NULL)) {
        error_setg(errp, "failed to load \"%s\"", vfio_dev_path);
        goto out_free_dev_path;
    }

    if (sscanf(contents, "%d:%d", &major, &minor) != 2) {
        error_setg(errp, "failed to get major:minor for \"%s\"", vfio_dev_path);
        goto out_free_dev_path;
    }
    g_free(contents);
    vfio_devt = makedev(major, minor);

    vfio_path = g_strdup_printf("/dev/vfio/devices/%s", dent->d_name);
    ret = open_cdev(vfio_path, vfio_devt);
    if (ret < 0) {
        error_setg(errp, "Failed to open %s", vfio_path);
    }

    trace_iommufd_cdev_getfd(vfio_path, ret);
    g_free(vfio_path);

out_free_dev_path:
    g_free(vfio_dev_path);
out_close_dir:
    closedir(dir);
out_free_path:
    if (*errp) {
        error_prepend(errp, VFIO_MSG_PREFIX, path);
    }
    g_free(path);

    return ret;
}

static int iommufd_cdev_attach_ioas_hwpt(VFIODevice *vbasedev, uint32_t id,
                                         Error **errp)
{
    int ret, iommufd = vbasedev->iommufd->fd;
    struct vfio_device_attach_iommufd_pt attach_data = {
        .argsz = sizeof(attach_data),
        .flags = 0,
        .pt_id = id,
    };

    /* Attach device to an IOAS or hwpt within iommufd */
    ret = ioctl(vbasedev->fd, VFIO_DEVICE_ATTACH_IOMMUFD_PT, &attach_data);
    if (ret) {
        error_setg_errno(errp, errno,
                         "[iommufd=%d] error attach %s (%d) to id=%d",
                         iommufd, vbasedev->name, vbasedev->fd, id);
    } else {
        trace_iommufd_cdev_attach_ioas_hwpt(iommufd, vbasedev->name,
                                            vbasedev->fd, id);
    }
    return ret;
}

static int iommufd_cdev_detach_ioas_hwpt(VFIODevice *vbasedev, Error **errp)
{
    int ret, iommufd = vbasedev->iommufd->fd;
    struct vfio_device_detach_iommufd_pt detach_data = {
        .argsz = sizeof(detach_data),
        .flags = 0,
    };

    ret = ioctl(vbasedev->fd, VFIO_DEVICE_DETACH_IOMMUFD_PT, &detach_data);
    if (ret) {
        error_setg_errno(errp, errno, "detach %s failed", vbasedev->name);
    } else {
        trace_iommufd_cdev_detach_ioas_hwpt(iommufd, vbasedev->name);
    }
    return ret;
}

static int iommufd_cdev_attach_container(VFIODevice *vbasedev,
                                         VFIOIOMMUFDContainer *container,
                                         Error **errp)
{
    return iommufd_cdev_attach_ioas_hwpt(vbasedev, container->ioas_id, errp);
}

static void iommufd_cdev_detach_container(VFIODevice *vbasedev,
                                          VFIOIOMMUFDContainer *container)
{
    Error *err = NULL;

    if (iommufd_cdev_detach_ioas_hwpt(vbasedev, &err)) {
        error_report_err(err);
    }
}

static void iommufd_cdev_container_destroy(VFIOIOMMUFDContainer *container)
{
    VFIOContainerBase *bcontainer = &container->bcontainer;

    if (!QLIST_EMPTY(&bcontainer->device_list)) {
        return;
    }
    memory_listener_unregister(&bcontainer->listener);
    vfio_container_destroy(bcontainer);
    iommufd_backend_free_id(container->be, container->ioas_id);
    g_free(container);
}

static int iommufd_cdev_ram_block_discard_disable(bool state)
{
    /*
     * We support coordinated discarding of RAM via the RamDiscardManager.
     */
    return ram_block_uncoordinated_discard_disable(state);
}

static int iommufd_cdev_attach(const char *name, VFIODevice *vbasedev,
                               AddressSpace *as, Error **errp)
{
    VFIOContainerBase *bcontainer;
    VFIOIOMMUFDContainer *container;
    VFIOAddressSpace *space;
    struct vfio_device_info dev_info = { .argsz = sizeof(dev_info) };
    int ret, devfd;
    uint32_t ioas_id;
    Error *err = NULL;

    devfd = iommufd_cdev_getfd(vbasedev->sysfsdev, errp);
    if (devfd < 0) {
        return devfd;
    }
    vbasedev->fd = devfd;

    ret = iommufd_cdev_connect_and_bind(vbasedev, errp);
    if (ret) {
        goto err_connect_bind;
    }

    space = vfio_get_address_space(as);

    /* try to attach to an existing container in this space */
    QLIST_FOREACH(bcontainer, &space->containers, next) {
        container = container_of(bcontainer, VFIOIOMMUFDContainer, bcontainer);
        if (bcontainer->ops != &vfio_iommufd_ops ||
            vbasedev->iommufd != container->be) {
            continue;
        }
        if (iommufd_cdev_attach_container(vbasedev, container, &err)) {
            const char *msg = error_get_pretty(err);

            trace_iommufd_cdev_fail_attach_existing_container(msg);
            error_free(err);
            err = NULL;
        } else {
            ret = iommufd_cdev_ram_block_discard_disable(true);
            if (ret) {
                error_setg(errp,
                              "Cannot set discarding of RAM broken (%d)", ret);
                goto err_discard_disable;
            }
            goto found_container;
        }
    }

    /* Need to allocate a new dedicated container */
    ret = iommufd_backend_alloc_ioas(vbasedev->iommufd, &ioas_id, errp);
    if (ret < 0) {
        goto err_alloc_ioas;
    }

    trace_iommufd_cdev_alloc_ioas(vbasedev->iommufd->fd, ioas_id);

    container = g_malloc0(sizeof(*container));
    container->be = vbasedev->iommufd;
    container->ioas_id = ioas_id;

    bcontainer = &container->bcontainer;
    vfio_container_init(bcontainer, space, &vfio_iommufd_ops);
    QLIST_INSERT_HEAD(&space->containers, bcontainer, next);

    ret = iommufd_cdev_attach_container(vbasedev, container, errp);
    if (ret) {
        goto err_attach_container;
    }

    ret = iommufd_cdev_ram_block_discard_disable(true);
    if (ret) {
        goto err_discard_disable;
    }

    bcontainer->pgsizes = qemu_real_host_page_size();

    bcontainer->listener = vfio_memory_listener;
    memory_listener_register(&bcontainer->listener, bcontainer->space->as);

    if (bcontainer->error) {
        ret = -1;
        error_propagate_prepend(errp, bcontainer->error,
                                "memory listener initialization failed: ");
        goto err_listener_register;
    }

    bcontainer->initialized = true;

found_container:
    ret = ioctl(devfd, VFIO_DEVICE_GET_INFO, &dev_info);
    if (ret) {
        error_setg_errno(errp, errno, "error getting device info");
        goto err_listener_register;
    }

    /*
     * TODO: examine RAM_BLOCK_DISCARD stuff, should we do group level
     * for discarding incompatibility check as well?
     */
    if (vbasedev->ram_block_discard_allowed) {
        iommufd_cdev_ram_block_discard_disable(false);
    }

    vbasedev->group = 0;
    vbasedev->num_irqs = dev_info.num_irqs;
    vbasedev->num_regions = dev_info.num_regions;
    vbasedev->flags = dev_info.flags;
    vbasedev->reset_works = !!(dev_info.flags & VFIO_DEVICE_FLAGS_RESET);
    vbasedev->bcontainer = bcontainer;
    QLIST_INSERT_HEAD(&bcontainer->device_list, vbasedev, container_next);
    QLIST_INSERT_HEAD(&vfio_device_list, vbasedev, global_next);

    trace_iommufd_cdev_device_info(vbasedev->name, devfd, vbasedev->num_irqs,
                                   vbasedev->num_regions, vbasedev->flags);
    return 0;

err_listener_register:
    iommufd_cdev_ram_block_discard_disable(false);
err_discard_disable:
    iommufd_cdev_detach_container(vbasedev, container);
err_attach_container:
    iommufd_cdev_container_destroy(container);
err_alloc_ioas:
    vfio_put_address_space(space);
    iommufd_cdev_unbind_and_disconnect(vbasedev);
err_connect_bind:
    close(vbasedev->fd);
    return ret;
}

static void iommufd_cdev_detach(VFIODevice *vbasedev)
{
    VFIOContainerBase *bcontainer = vbasedev->bcontainer;
    VFIOAddressSpace *space = bcontainer->space;
    VFIOIOMMUFDContainer *container = container_of(bcontainer,
                                                   VFIOIOMMUFDContainer,
                                                   bcontainer);
    QLIST_REMOVE(vbasedev, global_next);
    QLIST_REMOVE(vbasedev, container_next);
    vbasedev->bcontainer = NULL;

    if (!vbasedev->ram_block_discard_allowed) {
        iommufd_cdev_ram_block_discard_disable(false);
    }

    iommufd_cdev_detach_container(vbasedev, container);
    iommufd_cdev_container_destroy(container);
    vfio_put_address_space(space);

    iommufd_cdev_unbind_and_disconnect(vbasedev);
    close(vbasedev->fd);
}

const VFIOIOMMUOps vfio_iommufd_ops = {
    .dma_map = iommufd_cdev_map,
    .dma_unmap = iommufd_cdev_unmap,
    .attach_device = iommufd_cdev_attach,
    .detach_device = iommufd_cdev_detach,
};