Adding upstream version 1:7.2+dfsg.upstream/1%7.2+dfsgupstream

Signed-off-by: Daniel Baumann <mail@daniel-baumann.ch>

1 files changed, 1942 insertions, 0 deletions

diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
new file mode 100644
index 00000000..7fb008bc
--- /dev/null
+++ b/hw/virtio/vhost.c
@@ -0,0 +1,1942 @@
+/*
+ * vhost support
+ *
+ * Copyright Red Hat, Inc. 2010
+ *
+ * Authors:
+ *  Michael S. Tsirkin <mst@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.  See
+ * the COPYING file in the top-level directory.
+ *
+ * Contributions after 2012-01-13 are licensed under the terms of the
+ * GNU GPL, version 2 or (at your option) any later version.
+ */
+
+#include "qemu/osdep.h"
+#include "qapi/error.h"
+#include "hw/virtio/vhost.h"
+#include "qemu/atomic.h"
+#include "qemu/range.h"
+#include "qemu/error-report.h"
+#include "qemu/memfd.h"
+#include "standard-headers/linux/vhost_types.h"
+#include "hw/virtio/virtio-bus.h"
+#include "hw/virtio/virtio-access.h"
+#include "migration/blocker.h"
+#include "migration/qemu-file-types.h"
+#include "sysemu/dma.h"
+#include "trace.h"
+
+/* enabled until disconnected backend stabilizes */
+#define _VHOST_DEBUG 1
+
+#ifdef _VHOST_DEBUG
+#define VHOST_OPS_DEBUG(retval, fmt, ...) \
+    do { \
+        error_report(fmt ": %s (%d)", ## __VA_ARGS__, \
+                     strerror(-retval), -retval); \
+    } while (0)
+#else
+#define VHOST_OPS_DEBUG(retval, fmt, ...) \
+    do { } while (0)
+#endif
+
+static struct vhost_log *vhost_log;
+static struct vhost_log *vhost_log_shm;
+
+static unsigned int used_memslots;
+static QLIST_HEAD(, vhost_dev) vhost_devices =
+    QLIST_HEAD_INITIALIZER(vhost_devices);
+
+bool vhost_has_free_slot(void)
+{
+    unsigned int slots_limit = ~0U;
+    struct vhost_dev *hdev;
+
+    QLIST_FOREACH(hdev, &vhost_devices, entry) {
+        unsigned int r = hdev->vhost_ops->vhost_backend_memslots_limit(hdev);
+        slots_limit = MIN(slots_limit, r);
+    }
+    return slots_limit > used_memslots;
+}
+
+static void vhost_dev_sync_region(struct vhost_dev *dev,
+                                  MemoryRegionSection *section,
+                                  uint64_t mfirst, uint64_t mlast,
+                                  uint64_t rfirst, uint64_t rlast)
+{
+    vhost_log_chunk_t *log = dev->log->log;
+
+    uint64_t start = MAX(mfirst, rfirst);
+    uint64_t end = MIN(mlast, rlast);
+    vhost_log_chunk_t *from = log + start / VHOST_LOG_CHUNK;
+    vhost_log_chunk_t *to = log + end / VHOST_LOG_CHUNK + 1;
+    uint64_t addr = QEMU_ALIGN_DOWN(start, VHOST_LOG_CHUNK);
+
+    if (end < start) {
+        return;
+    }
+    assert(end / VHOST_LOG_CHUNK < dev->log_size);
+    assert(start / VHOST_LOG_CHUNK < dev->log_size);
+
+    for (;from < to; ++from) {
+        vhost_log_chunk_t log;
+        /* We first check with non-atomic: much cheaper,
+         * and we expect non-dirty to be the common case. */
+        if (!*from) {
+            addr += VHOST_LOG_CHUNK;
+            continue;
+        }
+        /* Data must be read atomically. We don't really need barrier semantics
+         * but it's easier to use atomic_* than roll our own. */
+        log = qatomic_xchg(from, 0);
+        while (log) {
+            int bit = ctzl(log);
+            hwaddr page_addr;
+            hwaddr section_offset;
+            hwaddr mr_offset;
+            page_addr = addr + bit * VHOST_LOG_PAGE;
+            section_offset = page_addr - section->offset_within_address_space;
+            mr_offset = section_offset + section->offset_within_region;
+            memory_region_set_dirty(section->mr, mr_offset, VHOST_LOG_PAGE);
+            log &= ~(0x1ull << bit);
+        }
+        addr += VHOST_LOG_CHUNK;
+    }
+}
+
+static int vhost_sync_dirty_bitmap(struct vhost_dev *dev,
+                                   MemoryRegionSection *section,
+                                   hwaddr first,
+                                   hwaddr last)
+{
+    int i;
+    hwaddr start_addr;
+    hwaddr end_addr;
+
+    if (!dev->log_enabled || !dev->started) {
+        return 0;
+    }
+    start_addr = section->offset_within_address_space;
+    end_addr = range_get_last(start_addr, int128_get64(section->size));
+    start_addr = MAX(first, start_addr);
+    end_addr = MIN(last, end_addr);
+
+    for (i = 0; i < dev->mem->nregions; ++i) {
+        struct vhost_memory_region *reg = dev->mem->regions + i;
+        vhost_dev_sync_region(dev, section, start_addr, end_addr,
+                              reg->guest_phys_addr,
+                              range_get_last(reg->guest_phys_addr,
+                                             reg->memory_size));
+    }
+    for (i = 0; i < dev->nvqs; ++i) {
+        struct vhost_virtqueue *vq = dev->vqs + i;
+
+        if (!vq->used_phys && !vq->used_size) {
+            continue;
+        }
+
+        vhost_dev_sync_region(dev, section, start_addr, end_addr, vq->used_phys,
+                              range_get_last(vq->used_phys, vq->used_size));
+    }
+    return 0;
+}
+
+static void vhost_log_sync(MemoryListener *listener,
+                          MemoryRegionSection *section)
+{
+    struct vhost_dev *dev = container_of(listener, struct vhost_dev,
+                                         memory_listener);
+    vhost_sync_dirty_bitmap(dev, section, 0x0, ~0x0ULL);
+}
+
+static void vhost_log_sync_range(struct vhost_dev *dev,
+                                 hwaddr first, hwaddr last)
+{
+    int i;
+    /* FIXME: this is N^2 in number of sections */
+    for (i = 0; i < dev->n_mem_sections; ++i) {
+        MemoryRegionSection *section = &dev->mem_sections[i];
+        vhost_sync_dirty_bitmap(dev, section, first, last);
+    }
+}
+
+static uint64_t vhost_get_log_size(struct vhost_dev *dev)
+{
+    uint64_t log_size = 0;
+    int i;
+    for (i = 0; i < dev->mem->nregions; ++i) {
+        struct vhost_memory_region *reg = dev->mem->regions + i;
+        uint64_t last = range_get_last(reg->guest_phys_addr,
+                                       reg->memory_size);
+        log_size = MAX(log_size, last / VHOST_LOG_CHUNK + 1);
+    }
+    return log_size;
+}
+
+static int vhost_set_backend_type(struct vhost_dev *dev,
+                                  VhostBackendType backend_type)
+{
+    int r = 0;
+
+    switch (backend_type) {
+#ifdef CONFIG_VHOST_KERNEL
+    case VHOST_BACKEND_TYPE_KERNEL:
+        dev->vhost_ops = &kernel_ops;
+        break;
+#endif
+#ifdef CONFIG_VHOST_USER
+    case VHOST_BACKEND_TYPE_USER:
+        dev->vhost_ops = &user_ops;
+        break;
+#endif
+#ifdef CONFIG_VHOST_VDPA
+    case VHOST_BACKEND_TYPE_VDPA:
+        dev->vhost_ops = &vdpa_ops;
+        break;
+#endif
+    default:
+        error_report("Unknown vhost backend type");
+        r = -1;
+    }
+
+    return r;
+}
+
+static struct vhost_log *vhost_log_alloc(uint64_t size, bool share)
+{
+    Error *err = NULL;
+    struct vhost_log *log;
+    uint64_t logsize = size * sizeof(*(log->log));
+    int fd = -1;
+
+    log = g_new0(struct vhost_log, 1);
+    if (share) {
+        log->log = qemu_memfd_alloc("vhost-log", logsize,
+                                    F_SEAL_GROW | F_SEAL_SHRINK | F_SEAL_SEAL,
+                                    &fd, &err);
+        if (err) {
+            error_report_err(err);
+            g_free(log);
+            return NULL;
+        }
+        memset(log->log, 0, logsize);
+    } else {
+        log->log = g_malloc0(logsize);
+    }
+
+    log->size = size;
+    log->refcnt = 1;
+    log->fd = fd;
+
+    return log;
+}
+
+static struct vhost_log *vhost_log_get(uint64_t size, bool share)
+{
+    struct vhost_log *log = share ? vhost_log_shm : vhost_log;
+
+    if (!log || log->size != size) {
+        log = vhost_log_alloc(size, share);
+        if (share) {
+            vhost_log_shm = log;
+        } else {
+            vhost_log = log;
+        }
+    } else {
+        ++log->refcnt;
+    }
+
+    return log;
+}
+
+static void vhost_log_put(struct vhost_dev *dev, bool sync)
+{
+    struct vhost_log *log = dev->log;
+
+    if (!log) {
+        return;
+    }
+
+    --log->refcnt;
+    if (log->refcnt == 0) {
+        /* Sync only the range covered by the old log */
+        if (dev->log_size && sync) {
+            vhost_log_sync_range(dev, 0, dev->log_size * VHOST_LOG_CHUNK - 1);
+        }
+
+        if (vhost_log == log) {
+            g_free(log->log);
+            vhost_log = NULL;
+        } else if (vhost_log_shm == log) {
+            qemu_memfd_free(log->log, log->size * sizeof(*(log->log)),
+                            log->fd);
+            vhost_log_shm = NULL;
+        }
+
+        g_free(log);
+    }
+
+    dev->log = NULL;
+    dev->log_size = 0;
+}
+
+static bool vhost_dev_log_is_shared(struct vhost_dev *dev)
+{
+    return dev->vhost_ops->vhost_requires_shm_log &&
+           dev->vhost_ops->vhost_requires_shm_log(dev);
+}
+
+static inline void vhost_dev_log_resize(struct vhost_dev *dev, uint64_t size)
+{
+    struct vhost_log *log = vhost_log_get(size, vhost_dev_log_is_shared(dev));
+    uint64_t log_base = (uintptr_t)log->log;
+    int r;
+
+    /* inform backend of log switching, this must be done before
+       releasing the current log, to ensure no logging is lost */
+    r = dev->vhost_ops->vhost_set_log_base(dev, log_base, log);
+    if (r < 0) {
+        VHOST_OPS_DEBUG(r, "vhost_set_log_base failed");
+    }
+
+    vhost_log_put(dev, true);
+    dev->log = log;
+    dev->log_size = size;
+}
+
+static bool vhost_dev_has_iommu(struct vhost_dev *dev)
+{
+    VirtIODevice *vdev = dev->vdev;
+
+    /*
+     * For vhost, VIRTIO_F_IOMMU_PLATFORM means the backend support
+     * incremental memory mapping API via IOTLB API. For platform that
+     * does not have IOMMU, there's no need to enable this feature
+     * which may cause unnecessary IOTLB miss/update transactions.
+     */
+    if (vdev) {
+        return virtio_bus_device_iommu_enabled(vdev) &&
+            virtio_host_has_feature(vdev, VIRTIO_F_IOMMU_PLATFORM);
+    } else {
+        return false;
+    }
+}
+
+static void *vhost_memory_map(struct vhost_dev *dev, hwaddr addr,
+                              hwaddr *plen, bool is_write)
+{
+    if (!vhost_dev_has_iommu(dev)) {
+        return cpu_physical_memory_map(addr, plen, is_write);
+    } else {
+        return (void *)(uintptr_t)addr;
+    }
+}
+
+static void vhost_memory_unmap(struct vhost_dev *dev, void *buffer,
+                               hwaddr len, int is_write,
+                               hwaddr access_len)
+{
+    if (!vhost_dev_has_iommu(dev)) {
+        cpu_physical_memory_unmap(buffer, len, is_write, access_len);
+    }
+}
+
+static int vhost_verify_ring_part_mapping(void *ring_hva,
+                                          uint64_t ring_gpa,
+                                          uint64_t ring_size,
+                                          void *reg_hva,
+                                          uint64_t reg_gpa,
+                                          uint64_t reg_size)
+{
+    uint64_t hva_ring_offset;
+    uint64_t ring_last = range_get_last(ring_gpa, ring_size);
+    uint64_t reg_last = range_get_last(reg_gpa, reg_size);
+
+    if (ring_last < reg_gpa || ring_gpa > reg_last) {
+        return 0;
+    }
+    /* check that whole ring's is mapped */
+    if (ring_last > reg_last) {
+        return -ENOMEM;
+    }
+    /* check that ring's MemoryRegion wasn't replaced */
+    hva_ring_offset = ring_gpa - reg_gpa;
+    if (ring_hva != reg_hva + hva_ring_offset) {
+        return -EBUSY;
+    }
+
+    return 0;
+}
+
+static int vhost_verify_ring_mappings(struct vhost_dev *dev,
+                                      void *reg_hva,
+                                      uint64_t reg_gpa,
+                                      uint64_t reg_size)
+{
+    int i, j;
+    int r = 0;
+    const char *part_name[] = {
+        "descriptor table",
+        "available ring",
+        "used ring"
+    };
+
+    if (vhost_dev_has_iommu(dev)) {
+        return 0;
+    }
+
+    for (i = 0; i < dev->nvqs; ++i) {
+        struct vhost_virtqueue *vq = dev->vqs + i;
+
+        if (vq->desc_phys == 0) {
+            continue;
+        }
+
+        j = 0;
+        r = vhost_verify_ring_part_mapping(
+                vq->desc, vq->desc_phys, vq->desc_size,
+                reg_hva, reg_gpa, reg_size);
+        if (r) {
+            break;
+        }
+
+        j++;
+        r = vhost_verify_ring_part_mapping(
+                vq->avail, vq->avail_phys, vq->avail_size,
+                reg_hva, reg_gpa, reg_size);
+        if (r) {
+            break;
+        }
+
+        j++;
+        r = vhost_verify_ring_part_mapping(
+                vq->used, vq->used_phys, vq->used_size,
+                reg_hva, reg_gpa, reg_size);
+        if (r) {
+            break;
+        }
+    }
+
+    if (r == -ENOMEM) {
+        error_report("Unable to map %s for ring %d", part_name[j], i);
+    } else if (r == -EBUSY) {
+        error_report("%s relocated for ring %d", part_name[j], i);
+    }
+    return r;
+}
+
+/*
+ * vhost_section: identify sections needed for vhost access
+ *
+ * We only care about RAM sections here (where virtqueue and guest
+ * internals accessed by virtio might live). If we find one we still
+ * allow the backend to potentially filter it out of our list.
+ */
+static bool vhost_section(struct vhost_dev *dev, MemoryRegionSection *section)
+{
+    MemoryRegion *mr = section->mr;
+
+    if (memory_region_is_ram(mr) && !memory_region_is_rom(mr)) {
+        uint8_t dirty_mask = memory_region_get_dirty_log_mask(mr);
+        uint8_t handled_dirty;
+
+        /*
+         * Kernel based vhost doesn't handle any block which is doing
+         * dirty-tracking other than migration for which it has
+         * specific logging support. However for TCG the kernel never
+         * gets involved anyway so we can also ignore it's
+         * self-modiying code detection flags. However a vhost-user
+         * client could still confuse a TCG guest if it re-writes
+         * executable memory that has already been translated.
+         */
+        handled_dirty = (1 << DIRTY_MEMORY_MIGRATION) |
+            (1 << DIRTY_MEMORY_CODE);
+
+        if (dirty_mask & ~handled_dirty) {
+            trace_vhost_reject_section(mr->name, 1);
+            return false;
+        }
+
+        if (dev->vhost_ops->vhost_backend_mem_section_filter &&
+            !dev->vhost_ops->vhost_backend_mem_section_filter(dev, section)) {
+            trace_vhost_reject_section(mr->name, 2);
+            return false;
+        }
+
+        trace_vhost_section(mr->name);
+        return true;
+    } else {
+        trace_vhost_reject_section(mr->name, 3);
+        return false;
+    }
+}
+
+static void vhost_begin(MemoryListener *listener)
+{
+    struct vhost_dev *dev = container_of(listener, struct vhost_dev,
+                                         memory_listener);
+    dev->tmp_sections = NULL;
+    dev->n_tmp_sections = 0;
+}
+
+static void vhost_commit(MemoryListener *listener)
+{
+    struct vhost_dev *dev = container_of(listener, struct vhost_dev,
+                                         memory_listener);
+    MemoryRegionSection *old_sections;
+    int n_old_sections;
+    uint64_t log_size;
+    size_t regions_size;
+    int r;
+    int i;
+    bool changed = false;
+
+    /* Note we can be called before the device is started, but then
+     * starting the device calls set_mem_table, so we need to have
+     * built the data structures.
+     */
+    old_sections = dev->mem_sections;
+    n_old_sections = dev->n_mem_sections;
+    dev->mem_sections = dev->tmp_sections;
+    dev->n_mem_sections = dev->n_tmp_sections;
+
+    if (dev->n_mem_sections != n_old_sections) {
+        changed = true;
+    } else {
+        /* Same size, lets check the contents */
+        for (int i = 0; i < n_old_sections; i++) {
+            if (!MemoryRegionSection_eq(&old_sections[i],
+                                        &dev->mem_sections[i])) {
+                changed = true;
+                break;
+            }
+        }
+    }
+
+    trace_vhost_commit(dev->started, changed);
+    if (!changed) {
+        goto out;
+    }
+
+    /* Rebuild the regions list from the new sections list */
+    regions_size = offsetof(struct vhost_memory, regions) +
+                       dev->n_mem_sections * sizeof dev->mem->regions[0];
+    dev->mem = g_realloc(dev->mem, regions_size);
+    dev->mem->nregions = dev->n_mem_sections;
+    used_memslots = dev->mem->nregions;
+    for (i = 0; i < dev->n_mem_sections; i++) {
+        struct vhost_memory_region *cur_vmr = dev->mem->regions + i;
+        struct MemoryRegionSection *mrs = dev->mem_sections + i;
+
+        cur_vmr->guest_phys_addr = mrs->offset_within_address_space;
+        cur_vmr->memory_size     = int128_get64(mrs->size);
+        cur_vmr->userspace_addr  =
+            (uintptr_t)memory_region_get_ram_ptr(mrs->mr) +
+            mrs->offset_within_region;
+        cur_vmr->flags_padding   = 0;
+    }
+
+    if (!dev->started) {
+        goto out;
+    }
+
+    for (i = 0; i < dev->mem->nregions; i++) {
+        if (vhost_verify_ring_mappings(dev,
+                       (void *)(uintptr_t)dev->mem->regions[i].userspace_addr,
+                       dev->mem->regions[i].guest_phys_addr,
+                       dev->mem->regions[i].memory_size)) {
+            error_report("Verify ring failure on region %d", i);
+            abort();
+        }
+    }
+
+    if (!dev->log_enabled) {
+        r = dev->vhost_ops->vhost_set_mem_table(dev, dev->mem);
+        if (r < 0) {
+            VHOST_OPS_DEBUG(r, "vhost_set_mem_table failed");
+        }
+        goto out;
+    }
+    log_size = vhost_get_log_size(dev);
+    /* We allocate an extra 4K bytes to log,
+     * to reduce the * number of reallocations. */
+#define VHOST_LOG_BUFFER (0x1000 / sizeof *dev->log)
+    /* To log more, must increase log size before table update. */
+    if (dev->log_size < log_size) {
+        vhost_dev_log_resize(dev, log_size + VHOST_LOG_BUFFER);
+    }
+    r = dev->vhost_ops->vhost_set_mem_table(dev, dev->mem);
+    if (r < 0) {
+        VHOST_OPS_DEBUG(r, "vhost_set_mem_table failed");
+    }
+    /* To log less, can only decrease log size after table update. */
+    if (dev->log_size > log_size + VHOST_LOG_BUFFER) {
+        vhost_dev_log_resize(dev, log_size);
+    }
+
+out:
+    /* Deref the old list of sections, this must happen _after_ the
+     * vhost_set_mem_table to ensure the client isn't still using the
+     * section we're about to unref.
+     */
+    while (n_old_sections--) {
+        memory_region_unref(old_sections[n_old_sections].mr);
+    }
+    g_free(old_sections);
+    return;
+}
+
+/* Adds the section data to the tmp_section structure.
+ * It relies on the listener calling us in memory address order
+ * and for each region (via the _add and _nop methods) to
+ * join neighbours.
+ */
+static void vhost_region_add_section(struct vhost_dev *dev,
+                                     MemoryRegionSection *section)
+{
+    bool need_add = true;
+    uint64_t mrs_size = int128_get64(section->size);
+    uint64_t mrs_gpa = section->offset_within_address_space;
+    uintptr_t mrs_host = (uintptr_t)memory_region_get_ram_ptr(section->mr) +
+                         section->offset_within_region;
+    RAMBlock *mrs_rb = section->mr->ram_block;
+
+    trace_vhost_region_add_section(section->mr->name, mrs_gpa, mrs_size,
+                                   mrs_host);
+
+    if (dev->vhost_ops->backend_type == VHOST_BACKEND_TYPE_USER) {
+        /* Round the section to it's page size */
+        /* First align the start down to a page boundary */
+        size_t mrs_page = qemu_ram_pagesize(mrs_rb);
+        uint64_t alignage = mrs_host & (mrs_page - 1);
+        if (alignage) {
+            mrs_host -= alignage;
+            mrs_size += alignage;
+            mrs_gpa  -= alignage;
+        }
+        /* Now align the size up to a page boundary */
+        alignage = mrs_size & (mrs_page - 1);
+        if (alignage) {
+            mrs_size += mrs_page - alignage;
+        }
+        trace_vhost_region_add_section_aligned(section->mr->name, mrs_gpa,
+                                               mrs_size, mrs_host);
+    }
+
+    if (dev->n_tmp_sections) {
+        /* Since we already have at least one section, lets see if
+         * this extends it; since we're scanning in order, we only
+         * have to look at the last one, and the FlatView that calls
+         * us shouldn't have overlaps.
+         */
+        MemoryRegionSection *prev_sec = dev->tmp_sections +
+                                               (dev->n_tmp_sections - 1);
+        uint64_t prev_gpa_start = prev_sec->offset_within_address_space;
+        uint64_t prev_size = int128_get64(prev_sec->size);
+        uint64_t prev_gpa_end   = range_get_last(prev_gpa_start, prev_size);
+        uint64_t prev_host_start =
+                        (uintptr_t)memory_region_get_ram_ptr(prev_sec->mr) +
+                        prev_sec->offset_within_region;
+        uint64_t prev_host_end   = range_get_last(prev_host_start, prev_size);
+
+        if (mrs_gpa <= (prev_gpa_end + 1)) {
+            /* OK, looks like overlapping/intersecting - it's possible that
+             * the rounding to page sizes has made them overlap, but they should
+             * match up in the same RAMBlock if they do.
+             */
+            if (mrs_gpa < prev_gpa_start) {
+                error_report("%s:Section '%s' rounded to %"PRIx64
+                             " prior to previous '%s' %"PRIx64,
+                             __func__, section->mr->name, mrs_gpa,
+                             prev_sec->mr->name, prev_gpa_start);
+                /* A way to cleanly fail here would be better */
+                return;
+            }
+            /* Offset from the start of the previous GPA to this GPA */
+            size_t offset = mrs_gpa - prev_gpa_start;
+
+            if (prev_host_start + offset == mrs_host &&
+                section->mr == prev_sec->mr &&
+                (!dev->vhost_ops->vhost_backend_can_merge ||
+                 dev->vhost_ops->vhost_backend_can_merge(dev,
+                    mrs_host, mrs_size,
+                    prev_host_start, prev_size))) {
+                uint64_t max_end = MAX(prev_host_end, mrs_host + mrs_size);
+                need_add = false;
+                prev_sec->offset_within_address_space =
+                    MIN(prev_gpa_start, mrs_gpa);
+                prev_sec->offset_within_region =
+                    MIN(prev_host_start, mrs_host) -
+                    (uintptr_t)memory_region_get_ram_ptr(prev_sec->mr);
+                prev_sec->size = int128_make64(max_end - MIN(prev_host_start,
+                                               mrs_host));
+                trace_vhost_region_add_section_merge(section->mr->name,
+                                        int128_get64(prev_sec->size),
+                                        prev_sec->offset_within_address_space,
+                                        prev_sec->offset_within_region);
+            } else {
+                /* adjoining regions are fine, but overlapping ones with
+                 * different blocks/offsets shouldn't happen
+                 */
+                if (mrs_gpa != prev_gpa_end + 1) {
+                    error_report("%s: Overlapping but not coherent sections "
+                                 "at %"PRIx64,
+                                 __func__, mrs_gpa);
+                    return;
+                }
+            }
+        }
+    }
+
+    if (need_add) {
+        ++dev->n_tmp_sections;
+        dev->tmp_sections = g_renew(MemoryRegionSection, dev->tmp_sections,
+                                    dev->n_tmp_sections);
+        dev->tmp_sections[dev->n_tmp_sections - 1] = *section;
+        /* The flatview isn't stable and we don't use it, making it NULL
+         * means we can memcmp the list.
+         */
+        dev->tmp_sections[dev->n_tmp_sections - 1].fv = NULL;
+        memory_region_ref(section->mr);
+    }
+}
+
+/* Used for both add and nop callbacks */
+static void vhost_region_addnop(MemoryListener *listener,
+                                MemoryRegionSection *section)
+{
+    struct vhost_dev *dev = container_of(listener, struct vhost_dev,
+                                         memory_listener);
+
+    if (!vhost_section(dev, section)) {
+        return;
+    }
+    vhost_region_add_section(dev, section);
+}
+
+static void vhost_iommu_unmap_notify(IOMMUNotifier *n, IOMMUTLBEntry *iotlb)
+{
+    struct vhost_iommu *iommu = container_of(n, struct vhost_iommu, n);
+    struct vhost_dev *hdev = iommu->hdev;
+    hwaddr iova = iotlb->iova + iommu->iommu_offset;
+
+    if (vhost_backend_invalidate_device_iotlb(hdev, iova,
+                                              iotlb->addr_mask + 1)) {
+        error_report("Fail to invalidate device iotlb");
+    }
+}
+
+static void vhost_iommu_region_add(MemoryListener *listener,
+                                   MemoryRegionSection *section)
+{
+    struct vhost_dev *dev = container_of(listener, struct vhost_dev,
+                                         iommu_listener);
+    struct vhost_iommu *iommu;
+    Int128 end;
+    int iommu_idx;
+    IOMMUMemoryRegion *iommu_mr;
+    int ret;
+
+    if (!memory_region_is_iommu(section->mr)) {
+        return;
+    }
+
+    iommu_mr = IOMMU_MEMORY_REGION(section->mr);
+
+    iommu = g_malloc0(sizeof(*iommu));
+    end = int128_add(int128_make64(section->offset_within_region),
+                     section->size);
+    end = int128_sub(end, int128_one());
+    iommu_idx = memory_region_iommu_attrs_to_index(iommu_mr,
+                                                   MEMTXATTRS_UNSPECIFIED);
+    iommu_notifier_init(&iommu->n, vhost_iommu_unmap_notify,
+                        IOMMU_NOTIFIER_DEVIOTLB_UNMAP,
+                        section->offset_within_region,
+                        int128_get64(end),
+                        iommu_idx);
+    iommu->mr = section->mr;
+    iommu->iommu_offset = section->offset_within_address_space -
+                          section->offset_within_region;
+    iommu->hdev = dev;
+    ret = memory_region_register_iommu_notifier(section->mr, &iommu->n, NULL);
+    if (ret) {
+        /*
+         * Some vIOMMUs do not support dev-iotlb yet.  If so, try to use the
+         * UNMAP legacy message
+         */
+        iommu->n.notifier_flags = IOMMU_NOTIFIER_UNMAP;
+        memory_region_register_iommu_notifier(section->mr, &iommu->n,
+                                              &error_fatal);
+    }
+    QLIST_INSERT_HEAD(&dev->iommu_list, iommu, iommu_next);
+    /* TODO: can replay help performance here? */
+}
+
+static void vhost_iommu_region_del(MemoryListener *listener,
+                                   MemoryRegionSection *section)
+{
+    struct vhost_dev *dev = container_of(listener, struct vhost_dev,
+                                         iommu_listener);
+    struct vhost_iommu *iommu;
+
+    if (!memory_region_is_iommu(section->mr)) {
+        return;
+    }
+
+    QLIST_FOREACH(iommu, &dev->iommu_list, iommu_next) {
+        if (iommu->mr == section->mr &&
+            iommu->n.start == section->offset_within_region) {
+            memory_region_unregister_iommu_notifier(iommu->mr,
+                                                    &iommu->n);
+            QLIST_REMOVE(iommu, iommu_next);
+            g_free(iommu);
+            break;
+        }
+    }
+}
+
+static int vhost_virtqueue_set_addr(struct vhost_dev *dev,
+                                    struct vhost_virtqueue *vq,
+                                    unsigned idx, bool enable_log)
+{
+    struct vhost_vring_addr addr;
+    int r;
+    memset(&addr, 0, sizeof(struct vhost_vring_addr));
+
+    if (dev->vhost_ops->vhost_vq_get_addr) {
+        r = dev->vhost_ops->vhost_vq_get_addr(dev, &addr, vq);
+        if (r < 0) {
+            VHOST_OPS_DEBUG(r, "vhost_vq_get_addr failed");
+            return r;
+        }
+    } else {
+        addr.desc_user_addr = (uint64_t)(unsigned long)vq->desc;
+        addr.avail_user_addr = (uint64_t)(unsigned long)vq->avail;
+        addr.used_user_addr = (uint64_t)(unsigned long)vq->used;
+    }
+    addr.index = idx;
+    addr.log_guest_addr = vq->used_phys;
+    addr.flags = enable_log ? (1 << VHOST_VRING_F_LOG) : 0;
+    r = dev->vhost_ops->vhost_set_vring_addr(dev, &addr);
+    if (r < 0) {
+        VHOST_OPS_DEBUG(r, "vhost_set_vring_addr failed");
+    }
+    return r;
+}
+
+static int vhost_dev_set_features(struct vhost_dev *dev,
+                                  bool enable_log)
+{
+    uint64_t features = dev->acked_features;
+    int r;
+    if (enable_log) {
+        features |= 0x1ULL << VHOST_F_LOG_ALL;
+    }
+    if (!vhost_dev_has_iommu(dev)) {
+        features &= ~(0x1ULL << VIRTIO_F_IOMMU_PLATFORM);
+    }
+    if (dev->vhost_ops->vhost_force_iommu) {
+        if (dev->vhost_ops->vhost_force_iommu(dev) == true) {
+            features |= 0x1ULL << VIRTIO_F_IOMMU_PLATFORM;
+       }
+    }
+    r = dev->vhost_ops->vhost_set_features(dev, features);
+    if (r < 0) {
+        VHOST_OPS_DEBUG(r, "vhost_set_features failed");
+        goto out;
+    }
+    if (dev->vhost_ops->vhost_set_backend_cap) {
+        r = dev->vhost_ops->vhost_set_backend_cap(dev);
+        if (r < 0) {
+            VHOST_OPS_DEBUG(r, "vhost_set_backend_cap failed");
+            goto out;
+        }
+    }
+
+out:
+    return r;
+}
+
+static int vhost_dev_set_log(struct vhost_dev *dev, bool enable_log)
+{
+    int r, i, idx;
+    hwaddr addr;
+
+    r = vhost_dev_set_features(dev, enable_log);
+    if (r < 0) {
+        goto err_features;
+    }
+    for (i = 0; i < dev->nvqs; ++i) {
+        idx = dev->vhost_ops->vhost_get_vq_index(dev, dev->vq_index + i);
+        addr = virtio_queue_get_desc_addr(dev->vdev, idx);
+        if (!addr) {
+            /*
+             * The queue might not be ready for start. If this
+             * is the case there is no reason to continue the process.
+             * The similar logic is used by the vhost_virtqueue_start()
+             * routine.
+             */
+            continue;
+        }
+        r = vhost_virtqueue_set_addr(dev, dev->vqs + i, idx,
+                                     enable_log);
+        if (r < 0) {
+            goto err_vq;
+        }
+    }
+    return 0;
+err_vq:
+    for (; i >= 0; --i) {
+        idx = dev->vhost_ops->vhost_get_vq_index(dev, dev->vq_index + i);
+        addr = virtio_queue_get_desc_addr(dev->vdev, idx);
+        if (!addr) {
+            continue;
+        }
+        vhost_virtqueue_set_addr(dev, dev->vqs + i, idx,
+                                 dev->log_enabled);
+    }
+    vhost_dev_set_features(dev, dev->log_enabled);
+err_features:
+    return r;
+}
+
+static int vhost_migration_log(MemoryListener *listener, bool enable)
+{
+    struct vhost_dev *dev = container_of(listener, struct vhost_dev,
+                                         memory_listener);
+    int r;
+    if (enable == dev->log_enabled) {
+        return 0;
+    }
+    if (!dev->started) {
+        dev->log_enabled = enable;
+        return 0;
+    }
+
+    r = 0;
+    if (!enable) {
+        r = vhost_dev_set_log(dev, false);
+        if (r < 0) {
+            goto check_dev_state;
+        }
+        vhost_log_put(dev, false);
+    } else {
+        vhost_dev_log_resize(dev, vhost_get_log_size(dev));
+        r = vhost_dev_set_log(dev, true);
+        if (r < 0) {
+            goto check_dev_state;
+        }
+    }
+
+check_dev_state:
+    dev->log_enabled = enable;
+    /*
+     * vhost-user-* devices could change their state during log
+     * initialization due to disconnect. So check dev state after
+     * vhost communication.
+     */
+    if (!dev->started) {
+        /*
+         * Since device is in the stopped state, it is okay for
+         * migration. Return success.
+         */
+        r = 0;
+    }
+    if (r) {
+        /* An error occurred. */
+        dev->log_enabled = false;
+    }
+
+    return r;
+}
+
+static void vhost_log_global_start(MemoryListener *listener)
+{
+    int r;
+
+    r = vhost_migration_log(listener, true);
+    if (r < 0) {
+        abort();
+    }
+}
+
+static void vhost_log_global_stop(MemoryListener *listener)
+{
+    int r;
+
+    r = vhost_migration_log(listener, false);
+    if (r < 0) {
+        abort();
+    }
+}
+
+static void vhost_log_start(MemoryListener *listener,
+                            MemoryRegionSection *section,
+                            int old, int new)
+{
+    /* FIXME: implement */
+}
+
+static void vhost_log_stop(MemoryListener *listener,
+                           MemoryRegionSection *section,
+                           int old, int new)
+{
+    /* FIXME: implement */
+}
+
+/* The vhost driver natively knows how to handle the vrings of non
+ * cross-endian legacy devices and modern devices. Only legacy devices
+ * exposed to a bi-endian guest may require the vhost driver to use a
+ * specific endianness.
+ */
+static inline bool vhost_needs_vring_endian(VirtIODevice *vdev)
+{
+    if (virtio_vdev_has_feature(vdev, VIRTIO_F_VERSION_1)) {
+        return false;
+    }
+#if HOST_BIG_ENDIAN
+    return vdev->device_endian == VIRTIO_DEVICE_ENDIAN_LITTLE;
+#else
+    return vdev->device_endian == VIRTIO_DEVICE_ENDIAN_BIG;
+#endif
+}
+
+static int vhost_virtqueue_set_vring_endian_legacy(struct vhost_dev *dev,
+                                                   bool is_big_endian,
+                                                   int vhost_vq_index)
+{
+    int r;
+    struct vhost_vring_state s = {
+        .index = vhost_vq_index,
+        .num = is_big_endian
+    };
+
+    r = dev->vhost_ops->vhost_set_vring_endian(dev, &s);
+    if (r < 0) {
+        VHOST_OPS_DEBUG(r, "vhost_set_vring_endian failed");
+    }
+    return r;
+}
+
+static int vhost_memory_region_lookup(struct vhost_dev *hdev,
+                                      uint64_t gpa, uint64_t *uaddr,
+                                      uint64_t *len)
+{
+    int i;
+
+    for (i = 0; i < hdev->mem->nregions; i++) {
+        struct vhost_memory_region *reg = hdev->mem->regions + i;
+
+        if (gpa >= reg->guest_phys_addr &&
+            reg->guest_phys_addr + reg->memory_size > gpa) {
+            *uaddr = reg->userspace_addr + gpa - reg->guest_phys_addr;
+            *len = reg->guest_phys_addr + reg->memory_size - gpa;
+            return 0;
+        }
+    }
+
+    return -EFAULT;
+}
+
+int vhost_device_iotlb_miss(struct vhost_dev *dev, uint64_t iova, int write)
+{
+    IOMMUTLBEntry iotlb;
+    uint64_t uaddr, len;
+    int ret = -EFAULT;
+
+    RCU_READ_LOCK_GUARD();
+
+    trace_vhost_iotlb_miss(dev, 1);
+
+    iotlb = address_space_get_iotlb_entry(dev->vdev->dma_as,
+                                          iova, write,
+                                          MEMTXATTRS_UNSPECIFIED);
+    if (iotlb.target_as != NULL) {
+        ret = vhost_memory_region_lookup(dev, iotlb.translated_addr,
+                                         &uaddr, &len);
+        if (ret) {
+            trace_vhost_iotlb_miss(dev, 3);
+            error_report("Fail to lookup the translated address "
+                         "%"PRIx64, iotlb.translated_addr);
+            goto out;
+        }
+
+        len = MIN(iotlb.addr_mask + 1, len);
+        iova = iova & ~iotlb.addr_mask;
+
+        ret = vhost_backend_update_device_iotlb(dev, iova, uaddr,
+                                                len, iotlb.perm);
+        if (ret) {
+            trace_vhost_iotlb_miss(dev, 4);
+            error_report("Fail to update device iotlb");
+            goto out;
+        }
+    }
+
+    trace_vhost_iotlb_miss(dev, 2);
+
+out:
+    return ret;
+}
+
+int vhost_virtqueue_start(struct vhost_dev *dev,
+                          struct VirtIODevice *vdev,
+                          struct vhost_virtqueue *vq,
+                          unsigned idx)
+{
+    BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(vdev)));
+    VirtioBusState *vbus = VIRTIO_BUS(qbus);
+    VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(vbus);
+    hwaddr s, l, a;
+    int r;
+    int vhost_vq_index = dev->vhost_ops->vhost_get_vq_index(dev, idx);
+    struct vhost_vring_file file = {
+        .index = vhost_vq_index
+    };
+    struct vhost_vring_state state = {
+        .index = vhost_vq_index
+    };
+    struct VirtQueue *vvq = virtio_get_queue(vdev, idx);
+
+    a = virtio_queue_get_desc_addr(vdev, idx);
+    if (a == 0) {
+        /* Queue might not be ready for start */
+        return 0;
+    }
+
+    vq->num = state.num = virtio_queue_get_num(vdev, idx);
+    r = dev->vhost_ops->vhost_set_vring_num(dev, &state);
+    if (r) {
+        VHOST_OPS_DEBUG(r, "vhost_set_vring_num failed");
+        return r;
+    }
+
+    state.num = virtio_queue_get_last_avail_idx(vdev, idx);
+    r = dev->vhost_ops->vhost_set_vring_base(dev, &state);
+    if (r) {
+        VHOST_OPS_DEBUG(r, "vhost_set_vring_base failed");
+        return r;
+    }
+
+    if (vhost_needs_vring_endian(vdev)) {
+        r = vhost_virtqueue_set_vring_endian_legacy(dev,
+                                                    virtio_is_big_endian(vdev),
+                                                    vhost_vq_index);
+        if (r) {
+            return r;
+        }
+    }
+
+    vq->desc_size = s = l = virtio_queue_get_desc_size(vdev, idx);
+    vq->desc_phys = a;
+    vq->desc = vhost_memory_map(dev, a, &l, false);
+    if (!vq->desc || l != s) {
+        r = -ENOMEM;
+        goto fail_alloc_desc;
+    }
+    vq->avail_size = s = l = virtio_queue_get_avail_size(vdev, idx);
+    vq->avail_phys = a = virtio_queue_get_avail_addr(vdev, idx);
+    vq->avail = vhost_memory_map(dev, a, &l, false);
+    if (!vq->avail || l != s) {
+        r = -ENOMEM;
+        goto fail_alloc_avail;
+    }
+    vq->used_size = s = l = virtio_queue_get_used_size(vdev, idx);
+    vq->used_phys = a = virtio_queue_get_used_addr(vdev, idx);
+    vq->used = vhost_memory_map(dev, a, &l, true);
+    if (!vq->used || l != s) {
+        r = -ENOMEM;
+        goto fail_alloc_used;
+    }
+
+    r = vhost_virtqueue_set_addr(dev, vq, vhost_vq_index, dev->log_enabled);
+    if (r < 0) {
+        goto fail_alloc;
+    }
+
+    file.fd = event_notifier_get_fd(virtio_queue_get_host_notifier(vvq));
+    r = dev->vhost_ops->vhost_set_vring_kick(dev, &file);
+    if (r) {
+        VHOST_OPS_DEBUG(r, "vhost_set_vring_kick failed");
+        goto fail_kick;
+    }
+
+    /* Clear and discard previous events if any. */
+    event_notifier_test_and_clear(&vq->masked_notifier);
+
+    /* Init vring in unmasked state, unless guest_notifier_mask
+     * will do it later.
+     */
+    if (!vdev->use_guest_notifier_mask) {
+        /* TODO: check and handle errors. */
+        vhost_virtqueue_mask(dev, vdev, idx, false);
+    }
+
+    if (k->query_guest_notifiers &&
+        k->query_guest_notifiers(qbus->parent) &&
+        virtio_queue_vector(vdev, idx) == VIRTIO_NO_VECTOR) {
+        file.fd = -1;
+        r = dev->vhost_ops->vhost_set_vring_call(dev, &file);
+        if (r) {
+            goto fail_vector;
+        }
+    }
+
+    return 0;
+
+fail_vector:
+fail_kick:
+fail_alloc:
+    vhost_memory_unmap(dev, vq->used, virtio_queue_get_used_size(vdev, idx),
+                       0, 0);
+fail_alloc_used:
+    vhost_memory_unmap(dev, vq->avail, virtio_queue_get_avail_size(vdev, idx),
+                       0, 0);
+fail_alloc_avail:
+    vhost_memory_unmap(dev, vq->desc, virtio_queue_get_desc_size(vdev, idx),
+                       0, 0);
+fail_alloc_desc:
+    return r;
+}
+
+void vhost_virtqueue_stop(struct vhost_dev *dev,
+                          struct VirtIODevice *vdev,
+                          struct vhost_virtqueue *vq,
+                          unsigned idx)
+{
+    int vhost_vq_index = dev->vhost_ops->vhost_get_vq_index(dev, idx);
+    struct vhost_vring_state state = {
+        .index = vhost_vq_index,
+    };
+    int r;
+
+    if (virtio_queue_get_desc_addr(vdev, idx) == 0) {
+        /* Don't stop the virtqueue which might have not been started */
+        return;
+    }
+
+    r = dev->vhost_ops->vhost_get_vring_base(dev, &state);
+    if (r < 0) {
+        VHOST_OPS_DEBUG(r, "vhost VQ %u ring restore failed: %d", idx, r);
+        /* Connection to the backend is broken, so let's sync internal
+         * last avail idx to the device used idx.
+         */
+        virtio_queue_restore_last_avail_idx(vdev, idx);
+    } else {
+        virtio_queue_set_last_avail_idx(vdev, idx, state.num);
+    }
+    virtio_queue_invalidate_signalled_used(vdev, idx);
+    virtio_queue_update_used_idx(vdev, idx);
+
+    /* In the cross-endian case, we need to reset the vring endianness to
+     * native as legacy devices expect so by default.
+     */
+    if (vhost_needs_vring_endian(vdev)) {
+        vhost_virtqueue_set_vring_endian_legacy(dev,
+                                                !virtio_is_big_endian(vdev),
+                                                vhost_vq_index);
+    }
+
+    vhost_memory_unmap(dev, vq->used, virtio_queue_get_used_size(vdev, idx),
+                       1, virtio_queue_get_used_size(vdev, idx));
+    vhost_memory_unmap(dev, vq->avail, virtio_queue_get_avail_size(vdev, idx),
+                       0, virtio_queue_get_avail_size(vdev, idx));
+    vhost_memory_unmap(dev, vq->desc, virtio_queue_get_desc_size(vdev, idx),
+                       0, virtio_queue_get_desc_size(vdev, idx));
+}
+
+static void vhost_eventfd_add(MemoryListener *listener,
+                              MemoryRegionSection *section,
+                              bool match_data, uint64_t data, EventNotifier *e)
+{
+}
+
+static void vhost_eventfd_del(MemoryListener *listener,
+                              MemoryRegionSection *section,
+                              bool match_data, uint64_t data, EventNotifier *e)
+{
+}
+
+static int vhost_virtqueue_set_busyloop_timeout(struct vhost_dev *dev,
+                                                int n, uint32_t timeout)
+{
+    int vhost_vq_index = dev->vhost_ops->vhost_get_vq_index(dev, n);
+    struct vhost_vring_state state = {
+        .index = vhost_vq_index,
+        .num = timeout,
+    };
+    int r;
+
+    if (!dev->vhost_ops->vhost_set_vring_busyloop_timeout) {
+        return -EINVAL;
+    }
+
+    r = dev->vhost_ops->vhost_set_vring_busyloop_timeout(dev, &state);
+    if (r) {
+        VHOST_OPS_DEBUG(r, "vhost_set_vring_busyloop_timeout failed");
+        return r;
+    }
+
+    return 0;
+}
+
+static void vhost_virtqueue_error_notifier(EventNotifier *n)
+{
+    struct vhost_virtqueue *vq = container_of(n, struct vhost_virtqueue,
+                                              error_notifier);
+    struct vhost_dev *dev = vq->dev;
+    int index = vq - dev->vqs;
+
+    if (event_notifier_test_and_clear(n) && dev->vdev) {
+        VHOST_OPS_DEBUG(-EINVAL,  "vhost vring error in virtqueue %d",
+                        dev->vq_index + index);
+    }
+}
+
+static int vhost_virtqueue_init(struct vhost_dev *dev,
+                                struct vhost_virtqueue *vq, int n)
+{
+    int vhost_vq_index = dev->vhost_ops->vhost_get_vq_index(dev, n);
+    struct vhost_vring_file file = {
+        .index = vhost_vq_index,
+    };
+    int r = event_notifier_init(&vq->masked_notifier, 0);
+    if (r < 0) {
+        return r;
+    }
+
+    file.fd = event_notifier_get_wfd(&vq->masked_notifier);
+    r = dev->vhost_ops->vhost_set_vring_call(dev, &file);
+    if (r) {
+        VHOST_OPS_DEBUG(r, "vhost_set_vring_call failed");
+        goto fail_call;
+    }
+
+    vq->dev = dev;
+
+    if (dev->vhost_ops->vhost_set_vring_err) {
+        r = event_notifier_init(&vq->error_notifier, 0);
+        if (r < 0) {
+            goto fail_call;
+        }
+
+        file.fd = event_notifier_get_fd(&vq->error_notifier);
+        r = dev->vhost_ops->vhost_set_vring_err(dev, &file);
+        if (r) {
+            VHOST_OPS_DEBUG(r, "vhost_set_vring_err failed");
+            goto fail_err;
+        }
+
+        event_notifier_set_handler(&vq->error_notifier,
+                                   vhost_virtqueue_error_notifier);
+    }
+
+    return 0;
+
+fail_err:
+    event_notifier_cleanup(&vq->error_notifier);
+fail_call:
+    event_notifier_cleanup(&vq->masked_notifier);
+    return r;
+}
+
+static void vhost_virtqueue_cleanup(struct vhost_virtqueue *vq)
+{
+    event_notifier_cleanup(&vq->masked_notifier);
+    if (vq->dev->vhost_ops->vhost_set_vring_err) {
+        event_notifier_set_handler(&vq->error_notifier, NULL);
+        event_notifier_cleanup(&vq->error_notifier);
+    }
+}
+
+int vhost_dev_init(struct vhost_dev *hdev, void *opaque,
+                   VhostBackendType backend_type, uint32_t busyloop_timeout,
+                   Error **errp)
+{
+    uint64_t features;
+    int i, r, n_initialized_vqs = 0;
+
+    hdev->vdev = NULL;
+    hdev->migration_blocker = NULL;
+
+    r = vhost_set_backend_type(hdev, backend_type);
+    assert(r >= 0);
+
+    r = hdev->vhost_ops->vhost_backend_init(hdev, opaque, errp);
+    if (r < 0) {
+        goto fail;
+    }
+
+    r = hdev->vhost_ops->vhost_set_owner(hdev);
+    if (r < 0) {
+        error_setg_errno(errp, -r, "vhost_set_owner failed");
+        goto fail;
+    }
+
+    r = hdev->vhost_ops->vhost_get_features(hdev, &features);
+    if (r < 0) {
+        error_setg_errno(errp, -r, "vhost_get_features failed");
+        goto fail;
+    }
+
+    for (i = 0; i < hdev->nvqs; ++i, ++n_initialized_vqs) {
+        r = vhost_virtqueue_init(hdev, hdev->vqs + i, hdev->vq_index + i);
+        if (r < 0) {
+            error_setg_errno(errp, -r, "Failed to initialize virtqueue %d", i);
+            goto fail;
+        }
+    }
+
+    if (busyloop_timeout) {
+        for (i = 0; i < hdev->nvqs; ++i) {
+            r = vhost_virtqueue_set_busyloop_timeout(hdev, hdev->vq_index + i,
+                                                     busyloop_timeout);
+            if (r < 0) {
+                error_setg_errno(errp, -r, "Failed to set busyloop timeout");
+                goto fail_busyloop;
+            }
+        }
+    }
+
+    hdev->features = features;
+
+    hdev->memory_listener = (MemoryListener) {
+        .name = "vhost",
+        .begin = vhost_begin,
+        .commit = vhost_commit,
+        .region_add = vhost_region_addnop,
+        .region_nop = vhost_region_addnop,
+        .log_start = vhost_log_start,
+        .log_stop = vhost_log_stop,
+        .log_sync = vhost_log_sync,
+        .log_global_start = vhost_log_global_start,
+        .log_global_stop = vhost_log_global_stop,
+        .eventfd_add = vhost_eventfd_add,
+        .eventfd_del = vhost_eventfd_del,
+        .priority = 10
+    };
+
+    hdev->iommu_listener = (MemoryListener) {
+        .name = "vhost-iommu",
+        .region_add = vhost_iommu_region_add,
+        .region_del = vhost_iommu_region_del,
+    };
+
+    if (hdev->migration_blocker == NULL) {
+        if (!(hdev->features & (0x1ULL << VHOST_F_LOG_ALL))) {
+            error_setg(&hdev->migration_blocker,
+                       "Migration disabled: vhost lacks VHOST_F_LOG_ALL feature.");
+        } else if (vhost_dev_log_is_shared(hdev) && !qemu_memfd_alloc_check()) {
+            error_setg(&hdev->migration_blocker,
+                       "Migration disabled: failed to allocate shared memory");
+        }
+    }
+
+    if (hdev->migration_blocker != NULL) {
+        r = migrate_add_blocker(hdev->migration_blocker, errp);
+        if (r < 0) {
+            error_free(hdev->migration_blocker);
+            goto fail_busyloop;
+        }
+    }
+
+    hdev->mem = g_malloc0(offsetof(struct vhost_memory, regions));
+    hdev->n_mem_sections = 0;
+    hdev->mem_sections = NULL;
+    hdev->log = NULL;
+    hdev->log_size = 0;
+    hdev->log_enabled = false;
+    hdev->started = false;
+    memory_listener_register(&hdev->memory_listener, &address_space_memory);
+    QLIST_INSERT_HEAD(&vhost_devices, hdev, entry);
+
+    if (used_memslots > hdev->vhost_ops->vhost_backend_memslots_limit(hdev)) {
+        error_setg(errp, "vhost backend memory slots limit is less"
+                   " than current number of present memory slots");
+        r = -EINVAL;
+        goto fail_busyloop;
+    }
+
+    return 0;
+
+fail_busyloop:
+    if (busyloop_timeout) {
+        while (--i >= 0) {
+            vhost_virtqueue_set_busyloop_timeout(hdev, hdev->vq_index + i, 0);
+        }
+    }
+fail:
+    hdev->nvqs = n_initialized_vqs;
+    vhost_dev_cleanup(hdev);
+    return r;
+}
+
+void vhost_dev_cleanup(struct vhost_dev *hdev)
+{
+    int i;
+
+    trace_vhost_dev_cleanup(hdev);
+
+    for (i = 0; i < hdev->nvqs; ++i) {
+        vhost_virtqueue_cleanup(hdev->vqs + i);
+    }
+    if (hdev->mem) {
+        /* those are only safe after successful init */
+        memory_listener_unregister(&hdev->memory_listener);
+        QLIST_REMOVE(hdev, entry);
+    }
+    if (hdev->migration_blocker) {
+        migrate_del_blocker(hdev->migration_blocker);
+        error_free(hdev->migration_blocker);
+    }
+    g_free(hdev->mem);
+    g_free(hdev->mem_sections);
+    if (hdev->vhost_ops) {
+        hdev->vhost_ops->vhost_backend_cleanup(hdev);
+    }
+    assert(!hdev->log);
+
+    memset(hdev, 0, sizeof(struct vhost_dev));
+}
+
+/* Stop processing guest IO notifications in qemu.
+ * Start processing them in vhost in kernel.
+ */
+int vhost_dev_enable_notifiers(struct vhost_dev *hdev, VirtIODevice *vdev)
+{
+    BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(vdev)));
+    int i, r, e;
+
+    /* We will pass the notifiers to the kernel, make sure that QEMU
+     * doesn't interfere.
+     */
+    r = virtio_device_grab_ioeventfd(vdev);
+    if (r < 0) {
+        error_report("binding does not support host notifiers");
+        goto fail;
+    }
+
+    for (i = 0; i < hdev->nvqs; ++i) {
+        r = virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), hdev->vq_index + i,
+                                         true);
+        if (r < 0) {
+            error_report("vhost VQ %d notifier binding failed: %d", i, -r);
+            goto fail_vq;
+        }
+    }
+
+    return 0;
+fail_vq:
+    while (--i >= 0) {
+        e = virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), hdev->vq_index + i,
+                                         false);
+        if (e < 0) {
+            error_report("vhost VQ %d notifier cleanup error: %d", i, -r);
+        }
+        assert (e >= 0);
+        virtio_bus_cleanup_host_notifier(VIRTIO_BUS(qbus), hdev->vq_index + i);
+    }
+    virtio_device_release_ioeventfd(vdev);
+fail:
+    return r;
+}
+
+/* Stop processing guest IO notifications in vhost.
+ * Start processing them in qemu.
+ * This might actually run the qemu handlers right away,
+ * so virtio in qemu must be completely setup when this is called.
+ */
+void vhost_dev_disable_notifiers(struct vhost_dev *hdev, VirtIODevice *vdev)
+{
+    BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(vdev)));
+    int i, r;
+
+    for (i = 0; i < hdev->nvqs; ++i) {
+        r = virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), hdev->vq_index + i,
+                                         false);
+        if (r < 0) {
+            error_report("vhost VQ %d notifier cleanup failed: %d", i, -r);
+        }
+        assert (r >= 0);
+        virtio_bus_cleanup_host_notifier(VIRTIO_BUS(qbus), hdev->vq_index + i);
+    }
+    virtio_device_release_ioeventfd(vdev);
+}
+
+/* Test and clear event pending status.
+ * Should be called after unmask to avoid losing events.
+ */
+bool vhost_virtqueue_pending(struct vhost_dev *hdev, int n)
+{
+    struct vhost_virtqueue *vq = hdev->vqs + n - hdev->vq_index;
+    assert(n >= hdev->vq_index && n < hdev->vq_index + hdev->nvqs);
+    return event_notifier_test_and_clear(&vq->masked_notifier);
+}
+
+/* Mask/unmask events from this vq. */
+void vhost_virtqueue_mask(struct vhost_dev *hdev, VirtIODevice *vdev, int n,
+                         bool mask)
+{
+    struct VirtQueue *vvq = virtio_get_queue(vdev, n);
+    int r, index = n - hdev->vq_index;
+    struct vhost_vring_file file;
+
+    /* should only be called after backend is connected */
+    assert(hdev->vhost_ops);
+
+    if (mask) {
+        assert(vdev->use_guest_notifier_mask);
+        file.fd = event_notifier_get_wfd(&hdev->vqs[index].masked_notifier);
+    } else {
+        file.fd = event_notifier_get_wfd(virtio_queue_get_guest_notifier(vvq));
+    }
+
+    file.index = hdev->vhost_ops->vhost_get_vq_index(hdev, n);
+    r = hdev->vhost_ops->vhost_set_vring_call(hdev, &file);
+    if (r < 0) {
+        VHOST_OPS_DEBUG(r, "vhost_set_vring_call failed");
+    }
+}
+
+uint64_t vhost_get_features(struct vhost_dev *hdev, const int *feature_bits,
+                            uint64_t features)
+{
+    const int *bit = feature_bits;
+    while (*bit != VHOST_INVALID_FEATURE_BIT) {
+        uint64_t bit_mask = (1ULL << *bit);
+        if (!(hdev->features & bit_mask)) {
+            features &= ~bit_mask;
+        }
+        bit++;
+    }
+    return features;
+}
+
+void vhost_ack_features(struct vhost_dev *hdev, const int *feature_bits,
+                        uint64_t features)
+{
+    const int *bit = feature_bits;
+    while (*bit != VHOST_INVALID_FEATURE_BIT) {
+        uint64_t bit_mask = (1ULL << *bit);
+        if (features & bit_mask) {
+            hdev->acked_features |= bit_mask;
+        }
+        bit++;
+    }
+}
+
+int vhost_dev_get_config(struct vhost_dev *hdev, uint8_t *config,
+                         uint32_t config_len, Error **errp)
+{
+    assert(hdev->vhost_ops);
+
+    if (hdev->vhost_ops->vhost_get_config) {
+        return hdev->vhost_ops->vhost_get_config(hdev, config, config_len,
+                                                 errp);
+    }
+
+    error_setg(errp, "vhost_get_config not implemented");
+    return -ENOSYS;
+}
+
+int vhost_dev_set_config(struct vhost_dev *hdev, const uint8_t *data,
+                         uint32_t offset, uint32_t size, uint32_t flags)
+{
+    assert(hdev->vhost_ops);
+
+    if (hdev->vhost_ops->vhost_set_config) {
+        return hdev->vhost_ops->vhost_set_config(hdev, data, offset,
+                                                 size, flags);
+    }
+
+    return -ENOSYS;
+}
+
+void vhost_dev_set_config_notifier(struct vhost_dev *hdev,
+                                   const VhostDevConfigOps *ops)
+{
+    hdev->config_ops = ops;
+}
+
+void vhost_dev_free_inflight(struct vhost_inflight *inflight)
+{
+    if (inflight && inflight->addr) {
+        qemu_memfd_free(inflight->addr, inflight->size, inflight->fd);
+        inflight->addr = NULL;
+        inflight->fd = -1;
+    }
+}
+
+static int vhost_dev_resize_inflight(struct vhost_inflight *inflight,
+                                     uint64_t new_size)
+{
+    Error *err = NULL;
+    int fd = -1;
+    void *addr = qemu_memfd_alloc("vhost-inflight", new_size,
+                                  F_SEAL_GROW | F_SEAL_SHRINK | F_SEAL_SEAL,
+                                  &fd, &err);
+
+    if (err) {
+        error_report_err(err);
+        return -ENOMEM;
+    }
+
+    vhost_dev_free_inflight(inflight);
+    inflight->offset = 0;
+    inflight->addr = addr;
+    inflight->fd = fd;
+    inflight->size = new_size;
+
+    return 0;
+}
+
+void vhost_dev_save_inflight(struct vhost_inflight *inflight, QEMUFile *f)
+{
+    if (inflight->addr) {
+        qemu_put_be64(f, inflight->size);
+        qemu_put_be16(f, inflight->queue_size);
+        qemu_put_buffer(f, inflight->addr, inflight->size);
+    } else {
+        qemu_put_be64(f, 0);
+    }
+}
+
+int vhost_dev_load_inflight(struct vhost_inflight *inflight, QEMUFile *f)
+{
+    uint64_t size;
+
+    size = qemu_get_be64(f);
+    if (!size) {
+        return 0;
+    }
+
+    if (inflight->size != size) {
+        int ret = vhost_dev_resize_inflight(inflight, size);
+        if (ret < 0) {
+            return ret;
+        }
+    }
+    inflight->queue_size = qemu_get_be16(f);
+
+    qemu_get_buffer(f, inflight->addr, size);
+
+    return 0;
+}
+
+int vhost_dev_prepare_inflight(struct vhost_dev *hdev, VirtIODevice *vdev)
+{
+    int r;
+
+    if (hdev->vhost_ops->vhost_get_inflight_fd == NULL ||
+        hdev->vhost_ops->vhost_set_inflight_fd == NULL) {
+        return 0;
+    }
+
+    hdev->vdev = vdev;
+
+    r = vhost_dev_set_features(hdev, hdev->log_enabled);
+    if (r < 0) {
+        VHOST_OPS_DEBUG(r, "vhost_dev_prepare_inflight failed");
+        return r;
+    }
+
+    return 0;
+}
+
+int vhost_dev_set_inflight(struct vhost_dev *dev,
+                           struct vhost_inflight *inflight)
+{
+    int r;
+
+    if (dev->vhost_ops->vhost_set_inflight_fd && inflight->addr) {
+        r = dev->vhost_ops->vhost_set_inflight_fd(dev, inflight);
+        if (r) {
+            VHOST_OPS_DEBUG(r, "vhost_set_inflight_fd failed");
+            return r;
+        }
+    }
+
+    return 0;
+}
+
+int vhost_dev_get_inflight(struct vhost_dev *dev, uint16_t queue_size,
+                           struct vhost_inflight *inflight)
+{
+    int r;
+
+    if (dev->vhost_ops->vhost_get_inflight_fd) {
+        r = dev->vhost_ops->vhost_get_inflight_fd(dev, queue_size, inflight);
+        if (r) {
+            VHOST_OPS_DEBUG(r, "vhost_get_inflight_fd failed");
+            return r;
+        }
+    }
+
+    return 0;
+}
+
+static int vhost_dev_set_vring_enable(struct vhost_dev *hdev, int enable)
+{
+    if (!hdev->vhost_ops->vhost_set_vring_enable) {
+        return 0;
+    }
+
+    /*
+     * For vhost-user devices, if VHOST_USER_F_PROTOCOL_FEATURES has not
+     * been negotiated, the rings start directly in the enabled state, and
+     * .vhost_set_vring_enable callback will fail since
+     * VHOST_USER_SET_VRING_ENABLE is not supported.
+     */
+    if (hdev->vhost_ops->backend_type == VHOST_BACKEND_TYPE_USER &&
+        !virtio_has_feature(hdev->backend_features,
+                            VHOST_USER_F_PROTOCOL_FEATURES)) {
+        return 0;
+    }
+
+    return hdev->vhost_ops->vhost_set_vring_enable(hdev, enable);
+}
+
+/* Host notifiers must be enabled at this point. */
+int vhost_dev_start(struct vhost_dev *hdev, VirtIODevice *vdev, bool vrings)
+{
+    int i, r;
+
+    /* should only be called after backend is connected */
+    assert(hdev->vhost_ops);
+
+    trace_vhost_dev_start(hdev, vdev->name, vrings);
+
+    vdev->vhost_started = true;
+    hdev->started = true;
+    hdev->vdev = vdev;
+
+    r = vhost_dev_set_features(hdev, hdev->log_enabled);
+    if (r < 0) {
+        goto fail_features;
+    }
+
+    if (vhost_dev_has_iommu(hdev)) {
+        memory_listener_register(&hdev->iommu_listener, vdev->dma_as);
+    }
+
+    r = hdev->vhost_ops->vhost_set_mem_table(hdev, hdev->mem);
+    if (r < 0) {
+        VHOST_OPS_DEBUG(r, "vhost_set_mem_table failed");
+        goto fail_mem;
+    }
+    for (i = 0; i < hdev->nvqs; ++i) {
+        r = vhost_virtqueue_start(hdev,
+                                  vdev,
+                                  hdev->vqs + i,
+                                  hdev->vq_index + i);
+        if (r < 0) {
+            goto fail_vq;
+        }
+    }
+
+    if (hdev->log_enabled) {
+        uint64_t log_base;
+
+        hdev->log_size = vhost_get_log_size(hdev);
+        hdev->log = vhost_log_get(hdev->log_size,
+                                  vhost_dev_log_is_shared(hdev));
+        log_base = (uintptr_t)hdev->log->log;
+        r = hdev->vhost_ops->vhost_set_log_base(hdev,
+                                                hdev->log_size ? log_base : 0,
+                                                hdev->log);
+        if (r < 0) {
+            VHOST_OPS_DEBUG(r, "vhost_set_log_base failed");
+            goto fail_log;
+        }
+    }
+    if (vrings) {
+        r = vhost_dev_set_vring_enable(hdev, true);
+        if (r) {
+            goto fail_log;
+        }
+    }
+    if (hdev->vhost_ops->vhost_dev_start) {
+        r = hdev->vhost_ops->vhost_dev_start(hdev, true);
+        if (r) {
+            goto fail_start;
+        }
+    }
+    if (vhost_dev_has_iommu(hdev) &&
+        hdev->vhost_ops->vhost_set_iotlb_callback) {
+            hdev->vhost_ops->vhost_set_iotlb_callback(hdev, true);
+
+        /* Update used ring information for IOTLB to work correctly,
+         * vhost-kernel code requires for this.*/
+        for (i = 0; i < hdev->nvqs; ++i) {
+            struct vhost_virtqueue *vq = hdev->vqs + i;
+            vhost_device_iotlb_miss(hdev, vq->used_phys, true);
+        }
+    }
+    return 0;
+fail_start:
+    if (vrings) {
+        vhost_dev_set_vring_enable(hdev, false);
+    }
+fail_log:
+    vhost_log_put(hdev, false);
+fail_vq:
+    while (--i >= 0) {
+        vhost_virtqueue_stop(hdev,
+                             vdev,
+                             hdev->vqs + i,
+                             hdev->vq_index + i);
+    }
+
+fail_mem:
+fail_features:
+    vdev->vhost_started = false;
+    hdev->started = false;
+    return r;
+}
+
+/* Host notifiers must be enabled at this point. */
+void vhost_dev_stop(struct vhost_dev *hdev, VirtIODevice *vdev, bool vrings)
+{
+    int i;
+
+    /* should only be called after backend is connected */
+    assert(hdev->vhost_ops);
+
+    trace_vhost_dev_stop(hdev, vdev->name, vrings);
+
+    if (hdev->vhost_ops->vhost_dev_start) {
+        hdev->vhost_ops->vhost_dev_start(hdev, false);
+    }
+    if (vrings) {
+        vhost_dev_set_vring_enable(hdev, false);
+    }
+    for (i = 0; i < hdev->nvqs; ++i) {
+        vhost_virtqueue_stop(hdev,
+                             vdev,
+                             hdev->vqs + i,
+                             hdev->vq_index + i);
+    }
+
+    if (vhost_dev_has_iommu(hdev)) {
+        if (hdev->vhost_ops->vhost_set_iotlb_callback) {
+            hdev->vhost_ops->vhost_set_iotlb_callback(hdev, false);
+        }
+        memory_listener_unregister(&hdev->iommu_listener);
+    }
+    vhost_log_put(hdev, true);
+    hdev->started = false;
+    vdev->vhost_started = false;
+    hdev->vdev = NULL;
+}
+
+int vhost_net_set_backend(struct vhost_dev *hdev,
+                          struct vhost_vring_file *file)
+{
+    if (hdev->vhost_ops->vhost_net_set_backend) {
+        return hdev->vhost_ops->vhost_net_set_backend(hdev, file);
+    }
+
+    return -ENOSYS;
+}