Archipelago » qemu

/*

 * 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 <sys/ioctl.h>

#include "vhost.h"

#include "hw/hw.h"

#include "range.h"

#include <linux/vhost.h>

#include "exec-memory.h"

static void vhost_dev_sync_region(struct vhost_dev *dev,

                                  MemoryRegionSection *section,

                                  uint64_t mfirst, uint64_t mlast,

                                  uint64_t rfirst, uint64_t rlast)

{

    uint64_t start = MAX(mfirst, rfirst);

    uint64_t end = MIN(mlast, rlast);

    vhost_log_chunk_t *from = dev->log + start / VHOST_LOG_CHUNK;

    vhost_log_chunk_t *to = dev->log + end / VHOST_LOG_CHUNK + 1;

    uint64_t addr = (start / VHOST_LOG_CHUNK) * 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;

        int bit;

        /* 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 the barrier semantics of __sync

         * builtins, but it's easier to use them than

         * roll our own. */

        log = __sync_fetch_and_and(from, 0);

        while ((bit = sizeof(log) > sizeof(int) ?

                ffsll(log) : ffs(log))) {

            ram_addr_t ram_addr;

            bit -= 1;

            ram_addr = section->offset_within_region + bit * VHOST_LOG_PAGE;

            memory_region_set_dirty(section->mr, ram_addr, VHOST_LOG_PAGE);

            log &= ~(0x1ull << bit);

        }

        addr += VHOST_LOG_CHUNK;

    }

}

static int vhost_sync_dirty_bitmap(struct vhost_dev *dev,

                                   MemoryRegionSection *section,

                                   target_phys_addr_t start_addr,

                                   target_phys_addr_t end_addr)

{

    int i;

    if (!dev->log_enabled || !dev->started) {

        return 0;

    }

    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;

        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);

    target_phys_addr_t start_addr = section->offset_within_address_space;

    target_phys_addr_t end_addr = start_addr + section->size;

    vhost_sync_dirty_bitmap(dev, section, start_addr, end_addr);

}

/* Assign/unassign. Keep an unsorted array of non-overlapping

 * memory regions in dev->mem. */

static void vhost_dev_unassign_memory(struct vhost_dev *dev,

                                      uint64_t start_addr,

                                      uint64_t size)

{

    int from, to, n = dev->mem->nregions;

    /* Track overlapping/split regions for sanity checking. */

    int overlap_start = 0, overlap_end = 0, overlap_middle = 0, split = 0;

    for (from = 0, to = 0; from < n; ++from, ++to) {

        struct vhost_memory_region *reg = dev->mem->regions + to;

        uint64_t reglast;

        uint64_t memlast;

        uint64_t change;

        /* clone old region */

        if (to != from) {

            memcpy(reg, dev->mem->regions + from, sizeof *reg);

        }

        /* No overlap is simple */

        if (!ranges_overlap(reg->guest_phys_addr, reg->memory_size,

                            start_addr, size)) {

            continue;

        }

        /* Split only happens if supplied region

         * is in the middle of an existing one. Thus it can not

         * overlap with any other existing region. */

        assert(!split);

        reglast = range_get_last(reg->guest_phys_addr, reg->memory_size);

        memlast = range_get_last(start_addr, size);

        /* Remove whole region */

        if (start_addr <= reg->guest_phys_addr && memlast >= reglast) {

            --dev->mem->nregions;

            --to;

            ++overlap_middle;

            continue;

        }

        /* Shrink region */

        if (memlast >= reglast) {

            reg->memory_size = start_addr - reg->guest_phys_addr;

            assert(reg->memory_size);

            assert(!overlap_end);

            ++overlap_end;

            continue;

        }

        /* Shift region */

        if (start_addr <= reg->guest_phys_addr) {

            change = memlast + 1 - reg->guest_phys_addr;

            reg->memory_size -= change;

            reg->guest_phys_addr += change;

            reg->userspace_addr += change;

            assert(reg->memory_size);

            assert(!overlap_start);

            ++overlap_start;

            continue;

        }

        /* This only happens if supplied region

         * is in the middle of an existing one. Thus it can not

         * overlap with any other existing region. */

        assert(!overlap_start);

        assert(!overlap_end);

        assert(!overlap_middle);

        /* Split region: shrink first part, shift second part. */

        memcpy(dev->mem->regions + n, reg, sizeof *reg);

        reg->memory_size = start_addr - reg->guest_phys_addr;

        assert(reg->memory_size);

        change = memlast + 1 - reg->guest_phys_addr;

        reg = dev->mem->regions + n;

        reg->memory_size -= change;

        assert(reg->memory_size);

        reg->guest_phys_addr += change;

        reg->userspace_addr += change;

        /* Never add more than 1 region */

        assert(dev->mem->nregions == n);

        ++dev->mem->nregions;

        ++split;

    }

}

/* Called after unassign, so no regions overlap the given range. */

static void vhost_dev_assign_memory(struct vhost_dev *dev,

                                    uint64_t start_addr,

                                    uint64_t size,

                                    uint64_t uaddr)

{

    int from, to;

    struct vhost_memory_region *merged = NULL;

    for (from = 0, to = 0; from < dev->mem->nregions; ++from, ++to) {

        struct vhost_memory_region *reg = dev->mem->regions + to;

        uint64_t prlast, urlast;

        uint64_t pmlast, umlast;

        uint64_t s, e, u;

        /* clone old region */

        if (to != from) {

            memcpy(reg, dev->mem->regions + from, sizeof *reg);

        }

        prlast = range_get_last(reg->guest_phys_addr, reg->memory_size);

        pmlast = range_get_last(start_addr, size);

        urlast = range_get_last(reg->userspace_addr, reg->memory_size);

        umlast = range_get_last(uaddr, size);

        /* check for overlapping regions: should never happen. */

        assert(prlast < start_addr || pmlast < reg->guest_phys_addr);

        /* Not an adjacent or overlapping region - do not merge. */

        if ((prlast + 1 != start_addr || urlast + 1 != uaddr) &&

            (pmlast + 1 != reg->guest_phys_addr ||

             umlast + 1 != reg->userspace_addr)) {

            continue;

        }

        if (merged) {

            --to;

            assert(to >= 0);

        } else {

            merged = reg;

        }

        u = MIN(uaddr, reg->userspace_addr);

        s = MIN(start_addr, reg->guest_phys_addr);

        e = MAX(pmlast, prlast);

        uaddr = merged->userspace_addr = u;

        start_addr = merged->guest_phys_addr = s;

        size = merged->memory_size = e - s + 1;

        assert(merged->memory_size);

    }

    if (!merged) {

        struct vhost_memory_region *reg = dev->mem->regions + to;

        memset(reg, 0, sizeof *reg);

        reg->memory_size = size;

        assert(reg->memory_size);

        reg->guest_phys_addr = start_addr;

        reg->userspace_addr = uaddr;

        ++to;

    }

    assert(to <= dev->mem->nregions + 1);

    dev->mem->nregions = to;

}

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);

    }

    for (i = 0; i < dev->nvqs; ++i) {

        struct vhost_virtqueue *vq = dev->vqs + i;

        uint64_t last = vq->used_phys + vq->used_size - 1;

        log_size = MAX(log_size, last / VHOST_LOG_CHUNK + 1);

    }

    return log_size;

}

static inline void vhost_dev_log_resize(struct vhost_dev* dev, uint64_t size)

{

    vhost_log_chunk_t *log;

    uint64_t log_base;

    int r, i;

    if (size) {

        log = g_malloc0(size * sizeof *log);

    } else {

        log = NULL;

    }

    log_base = (uint64_t)(unsigned long)log;

    r = ioctl(dev->control, VHOST_SET_LOG_BASE, &log_base);

    assert(r >= 0);

    for (i = 0; i < dev->n_mem_sections; ++i) {

        /* Sync only the range covered by the old log */

        vhost_sync_dirty_bitmap(dev, &dev->mem_sections[i], 0,

                                dev->log_size * VHOST_LOG_CHUNK - 1);

    }

    if (dev->log) {

        g_free(dev->log);

    }

    dev->log = log;

    dev->log_size = size;

}

static int vhost_verify_ring_mappings(struct vhost_dev *dev,

                                      uint64_t start_addr,

                                      uint64_t size)

{

    int i;

    for (i = 0; i < dev->nvqs; ++i) {

        struct vhost_virtqueue *vq = dev->vqs + i;

        target_phys_addr_t l;

        void *p;

        if (!ranges_overlap(start_addr, size, vq->ring_phys, vq->ring_size)) {

            continue;

        }

        l = vq->ring_size;

        p = cpu_physical_memory_map(vq->ring_phys, &l, 1);

        if (!p || l != vq->ring_size) {

            fprintf(stderr, "Unable to map ring buffer for ring %d\n", i);

            return -ENOMEM;

        }

        if (p != vq->ring) {

            fprintf(stderr, "Ring buffer relocated for ring %d\n", i);

            return -EBUSY;

        }

        cpu_physical_memory_unmap(p, l, 0, 0);

    }

    return 0;

}

static struct vhost_memory_region *vhost_dev_find_reg(struct vhost_dev *dev,

                                                      uint64_t start_addr,

                                                      uint64_t size)

{

    int i, n = dev->mem->nregions;

    for (i = 0; i < n; ++i) {

        struct vhost_memory_region *reg = dev->mem->regions + i;

        if (ranges_overlap(reg->guest_phys_addr, reg->memory_size,

                           start_addr, size)) {

            return reg;

        }

    }

    return NULL;

}

static bool vhost_dev_cmp_memory(struct vhost_dev *dev,

                                 uint64_t start_addr,

                                 uint64_t size,

                                 uint64_t uaddr)

{

    struct vhost_memory_region *reg = vhost_dev_find_reg(dev, start_addr, size);

    uint64_t reglast;

    uint64_t memlast;

    if (!reg) {

        return true;

    }

    reglast = range_get_last(reg->guest_phys_addr, reg->memory_size);

    memlast = range_get_last(start_addr, size);

    /* Need to extend region? */

    if (start_addr < reg->guest_phys_addr || memlast > reglast) {

        return true;

    }

    /* userspace_addr changed? */

    return uaddr != reg->userspace_addr + start_addr - reg->guest_phys_addr;

}

static void vhost_set_memory(MemoryListener *listener,

                             MemoryRegionSection *section,

                             bool add)

{

    struct vhost_dev *dev = container_of(listener, struct vhost_dev,

                                         memory_listener);

    target_phys_addr_t start_addr = section->offset_within_address_space;

    ram_addr_t size = section->size;

    bool log_dirty = memory_region_is_logging(section->mr);

    int s = offsetof(struct vhost_memory, regions) +

        (dev->mem->nregions + 1) * sizeof dev->mem->regions[0];

    uint64_t log_size;

    int r;

    void *ram;

    dev->mem = g_realloc(dev->mem, s);

    if (log_dirty) {

        add = false;

    }

    assert(size);

    /* Optimize no-change case. At least cirrus_vga does this a lot at this time. */

    ram = memory_region_get_ram_ptr(section->mr) + section->offset_within_region;

    if (add) {

        if (!vhost_dev_cmp_memory(dev, start_addr, size, (uintptr_t)ram)) {

            /* Region exists with same address. Nothing to do. */

            return;

        }

    } else {

        if (!vhost_dev_find_reg(dev, start_addr, size)) {

            /* Removing region that we don't access. Nothing to do. */

            return;

        }

    }

    vhost_dev_unassign_memory(dev, start_addr, size);

    if (add) {

        /* Add given mapping, merging adjacent regions if any */

        vhost_dev_assign_memory(dev, start_addr, size, (uintptr_t)ram);

    } else {

        /* Remove old mapping for this memory, if any. */

        vhost_dev_unassign_memory(dev, start_addr, size);

    }

    if (!dev->started) {

        return;

    }

    if (dev->started) {

        r = vhost_verify_ring_mappings(dev, start_addr, size);

        assert(r >= 0);

    }

    if (!dev->log_enabled) {

        r = ioctl(dev->control, VHOST_SET_MEM_TABLE, dev->mem);

        assert(r >= 0);

        return;

    }

    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 = ioctl(dev->control, VHOST_SET_MEM_TABLE, dev->mem);

    assert(r >= 0);

    /* 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);

    }

}

static bool vhost_section(MemoryRegionSection *section)

{

    return section->address_space == get_system_memory()

        && memory_region_is_ram(section->mr);

}

static void vhost_begin(MemoryListener *listener)

{

}

static void vhost_commit(MemoryListener *listener)

{

}

static void vhost_region_add(MemoryListener *listener,

                             MemoryRegionSection *section)

{

    struct vhost_dev *dev = container_of(listener, struct vhost_dev,

                                         memory_listener);

    if (!vhost_section(section)) {

        return;

    }

    ++dev->n_mem_sections;

    dev->mem_sections = g_renew(MemoryRegionSection, dev->mem_sections,

                                dev->n_mem_sections);

    dev->mem_sections[dev->n_mem_sections - 1] = *section;

    vhost_set_memory(listener, section, true);

}

static void vhost_region_del(MemoryListener *listener,

                             MemoryRegionSection *section)

{

    struct vhost_dev *dev = container_of(listener, struct vhost_dev,

                                         memory_listener);

    int i;

    if (!vhost_section(section)) {

        return;

    }

    vhost_set_memory(listener, section, false);

    for (i = 0; i < dev->n_mem_sections; ++i) {

        if (dev->mem_sections[i].offset_within_address_space

            == section->offset_within_address_space) {

            --dev->n_mem_sections;

            memmove(&dev->mem_sections[i], &dev->mem_sections[i+1],

                    (dev->n_mem_sections - i) * sizeof(*dev->mem_sections));

            break;

        }

    }

}

static void vhost_region_nop(MemoryListener *listener,

                             MemoryRegionSection *section)

{

}

static int vhost_virtqueue_set_addr(struct vhost_dev *dev,

                                    struct vhost_virtqueue *vq,

                                    unsigned idx, bool enable_log)

{

    struct vhost_vring_addr addr = {

        .index = idx,

        .desc_user_addr = (uint64_t)(unsigned long)vq->desc,

        .avail_user_addr = (uint64_t)(unsigned long)vq->avail,

        .used_user_addr = (uint64_t)(unsigned long)vq->used,

        .log_guest_addr = vq->used_phys,

        .flags = enable_log ? (1 << VHOST_VRING_F_LOG) : 0,

    };

    int r = ioctl(dev->control, VHOST_SET_VRING_ADDR, &addr);

    if (r < 0) {

        return -errno;

    }

    return 0;

}

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 |= 0x1 << VHOST_F_LOG_ALL;

    }

    r = ioctl(dev->control, VHOST_SET_FEATURES, &features);

    return r < 0 ? -errno : 0;

}

static int vhost_dev_set_log(struct vhost_dev *dev, bool enable_log)

{

    int r, t, i;

    r = vhost_dev_set_features(dev, enable_log);

    if (r < 0) {

        goto err_features;

    }

    for (i = 0; i < dev->nvqs; ++i) {

        r = vhost_virtqueue_set_addr(dev, dev->vqs + i, i,

                                     enable_log);

        if (r < 0) {

            goto err_vq;

        }

    }

    return 0;

err_vq:

    for (; i >= 0; --i) {

        t = vhost_virtqueue_set_addr(dev, dev->vqs + i, i,

                                     dev->log_enabled);

        assert(t >= 0);

    }

    t = vhost_dev_set_features(dev, dev->log_enabled);

    assert(t >= 0);

err_features:

    return r;

}

static int vhost_migration_log(MemoryListener *listener, int 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;

    }

    if (!enable) {

        r = vhost_dev_set_log(dev, false);

        if (r < 0) {

            return r;

        }

        if (dev->log) {

            g_free(dev->log);

        }

        dev->log = NULL;

        dev->log_size = 0;

    } else {

        vhost_dev_log_resize(dev, vhost_get_log_size(dev));

        r = vhost_dev_set_log(dev, true);

        if (r < 0) {

            return r;

        }

    }

    dev->log_enabled = enable;

    return 0;

}

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)

{

    /* FIXME: implement */

}

static void vhost_log_stop(MemoryListener *listener,

                           MemoryRegionSection *section)

{

    /* FIXME: implement */

}

static int vhost_virtqueue_init(struct vhost_dev *dev,

                                struct VirtIODevice *vdev,

                                struct vhost_virtqueue *vq,

                                unsigned idx)

{

    target_phys_addr_t s, l, a;

    int r;

    struct vhost_vring_file file = {

        .index = idx,

    };

    struct vhost_vring_state state = {

        .index = idx,

    };

    struct VirtQueue *vvq = virtio_get_queue(vdev, idx);

    vq->num = state.num = virtio_queue_get_num(vdev, idx);

    r = ioctl(dev->control, VHOST_SET_VRING_NUM, &state);

    if (r) {

        return -errno;

    }

    state.num = virtio_queue_get_last_avail_idx(vdev, idx);

    r = ioctl(dev->control, VHOST_SET_VRING_BASE, &state);

    if (r) {

        return -errno;

    }

    s = l = virtio_queue_get_desc_size(vdev, idx);

    a = virtio_queue_get_desc_addr(vdev, idx);

    vq->desc = cpu_physical_memory_map(a, &l, 0);

    if (!vq->desc || l != s) {

        r = -ENOMEM;

        goto fail_alloc_desc;

    }

    s = l = virtio_queue_get_avail_size(vdev, idx);

    a = virtio_queue_get_avail_addr(vdev, idx);

    vq->avail = cpu_physical_memory_map(a, &l, 0);

    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 = cpu_physical_memory_map(a, &l, 1);

    if (!vq->used || l != s) {

        r = -ENOMEM;

        goto fail_alloc_used;

    }

    vq->ring_size = s = l = virtio_queue_get_ring_size(vdev, idx);

    vq->ring_phys = a = virtio_queue_get_ring_addr(vdev, idx);

    vq->ring = cpu_physical_memory_map(a, &l, 1);

    if (!vq->ring || l != s) {

        r = -ENOMEM;

        goto fail_alloc_ring;

    }

    r = vhost_virtqueue_set_addr(dev, vq, idx, dev->log_enabled);

    if (r < 0) {

        r = -errno;

        goto fail_alloc;

    }

    file.fd = event_notifier_get_fd(virtio_queue_get_host_notifier(vvq));

    r = ioctl(dev->control, VHOST_SET_VRING_KICK, &file);

    if (r) {

        r = -errno;

        goto fail_kick;

    }

    file.fd = event_notifier_get_fd(virtio_queue_get_guest_notifier(vvq));

    r = ioctl(dev->control, VHOST_SET_VRING_CALL, &file);

    if (r) {

        r = -errno;

        goto fail_call;

    }

    return 0;

fail_call:

fail_kick:

fail_alloc:

    cpu_physical_memory_unmap(vq->ring, virtio_queue_get_ring_size(vdev, idx),

                              0, 0);

fail_alloc_ring:

    cpu_physical_memory_unmap(vq->used, virtio_queue_get_used_size(vdev, idx),

                              0, 0);

fail_alloc_used:

    cpu_physical_memory_unmap(vq->avail, virtio_queue_get_avail_size(vdev, idx),

                              0, 0);

fail_alloc_avail:

    cpu_physical_memory_unmap(vq->desc, virtio_queue_get_desc_size(vdev, idx),

                              0, 0);

fail_alloc_desc:

    return r;

}

static void vhost_virtqueue_cleanup(struct vhost_dev *dev,

                                    struct VirtIODevice *vdev,

                                    struct vhost_virtqueue *vq,

                                    unsigned idx)

{

    struct vhost_vring_state state = {

        .index = idx,

    };

    int r;

    r = ioctl(dev->control, VHOST_GET_VRING_BASE, &state);

    if (r < 0) {

        fprintf(stderr, "vhost VQ %d ring restore failed: %d\n", idx, r);

        fflush(stderr);

    }

    virtio_queue_set_last_avail_idx(vdev, idx, state.num);

    assert (r >= 0);

    cpu_physical_memory_unmap(vq->ring, virtio_queue_get_ring_size(vdev, idx),

                              0, virtio_queue_get_ring_size(vdev, idx));

    cpu_physical_memory_unmap(vq->used, virtio_queue_get_used_size(vdev, idx),

                              1, virtio_queue_get_used_size(vdev, idx));

    cpu_physical_memory_unmap(vq->avail, virtio_queue_get_avail_size(vdev, idx),

                              0, virtio_queue_get_avail_size(vdev, idx));

    cpu_physical_memory_unmap(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)

{

}

int vhost_dev_init(struct vhost_dev *hdev, int devfd, const char *devpath,

                   bool force)

{

    uint64_t features;

    int r;

    if (devfd >= 0) {

        hdev->control = devfd;

    } else {

        hdev->control = open(devpath, O_RDWR);

        if (hdev->control < 0) {

            return -errno;

        }

    }

    r = ioctl(hdev->control, VHOST_SET_OWNER, NULL);

    if (r < 0) {

        goto fail;

    }

    r = ioctl(hdev->control, VHOST_GET_FEATURES, &features);

    if (r < 0) {

        goto fail;

    }

    hdev->features = features;

    hdev->memory_listener = (MemoryListener) {

        .begin = vhost_begin,

        .commit = vhost_commit,

        .region_add = vhost_region_add,

        .region_del = vhost_region_del,

        .region_nop = vhost_region_nop,

        .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->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, NULL);

    hdev->force = force;

    return 0;

fail:

    r = -errno;

    close(hdev->control);

    return r;

}

void vhost_dev_cleanup(struct vhost_dev *hdev)

{

    memory_listener_unregister(&hdev->memory_listener);

    g_free(hdev->mem);

    g_free(hdev->mem_sections);

    close(hdev->control);

}

bool vhost_dev_query(struct vhost_dev *hdev, VirtIODevice *vdev)

{

    return !vdev->binding->query_guest_notifiers ||

        vdev->binding->query_guest_notifiers(vdev->binding_opaque) ||

        hdev->force;

}

/* 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)

{

    int i, r;

    if (!vdev->binding->set_host_notifier) {

        fprintf(stderr, "binding does not support host notifiers\n");

        r = -ENOSYS;

        goto fail;

    }

    for (i = 0; i < hdev->nvqs; ++i) {

        r = vdev->binding->set_host_notifier(vdev->binding_opaque, i, true);

        if (r < 0) {

            fprintf(stderr, "vhost VQ %d notifier binding failed: %d\n", i, -r);

            goto fail_vq;

        }

    }

    return 0;

fail_vq:

    while (--i >= 0) {

        r = vdev->binding->set_host_notifier(vdev->binding_opaque, i, false);

        if (r < 0) {

            fprintf(stderr, "vhost VQ %d notifier cleanup error: %d\n", i, -r);

            fflush(stderr);

        }

        assert (r >= 0);

    }

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)

{

    int i, r;

    for (i = 0; i < hdev->nvqs; ++i) {

        r = vdev->binding->set_host_notifier(vdev->binding_opaque, i, false);

        if (r < 0) {

            fprintf(stderr, "vhost VQ %d notifier cleanup failed: %d\n", i, -r);

            fflush(stderr);

        }

        assert (r >= 0);

    }

}

/* Host notifiers must be enabled at this point. */

int vhost_dev_start(struct vhost_dev *hdev, VirtIODevice *vdev)

{

    int i, r;

    if (!vdev->binding->set_guest_notifiers) {

        fprintf(stderr, "binding does not support guest notifiers\n");

        r = -ENOSYS;

        goto fail;

    }

    r = vdev->binding->set_guest_notifiers(vdev->binding_opaque, true);

    if (r < 0) {

        fprintf(stderr, "Error binding guest notifier: %d\n", -r);

        goto fail_notifiers;

    }

    r = vhost_dev_set_features(hdev, hdev->log_enabled);

    if (r < 0) {

        goto fail_features;

    }

    r = ioctl(hdev->control, VHOST_SET_MEM_TABLE, hdev->mem);

    if (r < 0) {

        r = -errno;

        goto fail_mem;

    }

    for (i = 0; i < hdev->nvqs; ++i) {

        r = vhost_virtqueue_init(hdev,

                                 vdev,

                                 hdev->vqs + i,

                                 i);

        if (r < 0) {

            goto fail_vq;

        }

    }

    if (hdev->log_enabled) {

        hdev->log_size = vhost_get_log_size(hdev);

        hdev->log = hdev->log_size ?

            g_malloc0(hdev->log_size * sizeof *hdev->log) : NULL;

        r = ioctl(hdev->control, VHOST_SET_LOG_BASE,

                  (uint64_t)(unsigned long)hdev->log);

        if (r < 0) {