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qemu/hw/virtio/vhost.c
Felipe Franciosi 5c0ba1be37 virtio/vhost: reset dev->log after syncing 
vhost_log_put() is called to decomission the dirty log between qemu and
a vhost device when stopping the device. Such a call can happen from
migration_completion().

Present code sets dev->log_size to zero too early in vhost_log_put(),
causing the sync check to always return false. As a consequence, the
last pass on the dirty bitmap never happens at the end of migration.

If a vhost device was busy (writing to guest memory) until the last
moments before vhost_virtqueue_stop(), this error will result in guest
memory corruption (at least) following migrations.

Signed-off-by: Felipe Franciosi <felipe@nutanix.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
2017-10-15 05:54:41 +03:00

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/*
* 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 "hw/hw.h"
#include "qemu/atomic.h"
#include "qemu/range.h"
#include "qemu/error-report.h"
#include "qemu/memfd.h"
#include <linux/vhost.h>
#include "exec/address-spaces.h"
#include "hw/virtio/virtio-bus.h"
#include "hw/virtio/virtio-access.h"
#include "migration/blocker.h"
#include "sysemu/dma.h"
/* enabled until disconnected backend stabilizes */
#define _VHOST_DEBUG 1
#ifdef _VHOST_DEBUG
#define VHOST_OPS_DEBUG(fmt, ...) \
do { error_report(fmt ": %s (%d)", ## __VA_ARGS__, \
strerror(errno), errno); } while (0)
#else
#define VHOST_OPS_DEBUG(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 = atomic_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;
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);
}
}
/* 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 (dev->vhost_ops->vhost_backend_can_merge &&
!dev->vhost_ops->vhost_backend_can_merge(dev, uaddr, size,
reg->userspace_addr,
reg->memory_size)) {
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 struct vhost_log *vhost_log_alloc(uint64_t size, bool share)
{
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);
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("vhost_set_log_base failed");
}
vhost_log_put(dev, true);
dev->log = log;
dev->log_size = size;
}
static int vhost_dev_has_iommu(struct vhost_dev *dev)
{
VirtIODevice *vdev = dev->vdev;
return virtio_host_has_feature(vdev, VIRTIO_F_IOMMU_PLATFORM);
}
static void *vhost_memory_map(struct vhost_dev *dev, hwaddr addr,
hwaddr *plen, int 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(struct vhost_dev *dev,
void *part,
uint64_t part_addr,
uint64_t part_size,
uint64_t start_addr,
uint64_t size)
{
hwaddr l;
void *p;
int r = 0;
if (!ranges_overlap(start_addr, size, part_addr, part_size)) {
return 0;
}
l = part_size;
p = vhost_memory_map(dev, part_addr, &l, 1);
if (!p || l != part_size) {
r = -ENOMEM;
}
if (p != part) {
r = -EBUSY;
}
vhost_memory_unmap(dev, p, l, 0, 0);
return r;
}
static int vhost_verify_ring_mappings(struct vhost_dev *dev,
uint64_t start_addr,
uint64_t size)
{
int i, j;
int r = 0;
const char *part_name[] = {
"descriptor table",
"available ring",
"used ring"
};
for (i = 0; i < dev->nvqs; ++i) {
struct vhost_virtqueue *vq = dev->vqs + i;
j = 0;
r = vhost_verify_ring_part_mapping(dev, vq->desc, vq->desc_phys,
vq->desc_size, start_addr, size);
if (!r) {
break;
}
j++;
r = vhost_verify_ring_part_mapping(dev, vq->avail, vq->avail_phys,
vq->avail_size, start_addr, size);
if (!r) {
break;
}
j++;
r = vhost_verify_ring_part_mapping(dev, vq->used, vq->used_phys,
vq->used_size, start_addr, 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;
}
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);
hwaddr start_addr = section->offset_within_address_space;
ram_addr_t size = int128_get64(section->size);
bool log_dirty =
memory_region_get_dirty_log_mask(section->mr) & ~(1 << DIRTY_MEMORY_MIGRATION);
int s = offsetof(struct vhost_memory, regions) +
(dev->mem->nregions + 1) * sizeof dev->mem->regions[0];
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);
}
dev->mem_changed_start_addr = MIN(dev->mem_changed_start_addr, start_addr);
dev->mem_changed_end_addr = MAX(dev->mem_changed_end_addr, start_addr + size - 1);
dev->memory_changed = true;
used_memslots = dev->mem->nregions;
}
static bool vhost_section(MemoryRegionSection *section)
{
return memory_region_is_ram(section->mr) &&
!memory_region_is_rom(section->mr);
}
static void vhost_begin(MemoryListener *listener)
{
struct vhost_dev *dev = container_of(listener, struct vhost_dev,
memory_listener);
dev->mem_changed_end_addr = 0;
dev->mem_changed_start_addr = -1;
}
static void vhost_commit(MemoryListener *listener)
{
struct vhost_dev *dev = container_of(listener, struct vhost_dev,
memory_listener);
hwaddr start_addr = 0;
ram_addr_t size = 0;
uint64_t log_size;
int r;
if (!dev->memory_changed) {
return;
}
if (!dev->started) {
return;
}
if (dev->mem_changed_start_addr > dev->mem_changed_end_addr) {
return;
}
if (dev->started) {
start_addr = dev->mem_changed_start_addr;
size = dev->mem_changed_end_addr - dev->mem_changed_start_addr + 1;
r = vhost_verify_ring_mappings(dev, start_addr, size);
assert(r >= 0);
}
if (!dev->log_enabled) {
r = dev->vhost_ops->vhost_set_mem_table(dev, dev->mem);
if (r < 0) {
VHOST_OPS_DEBUG("vhost_set_mem_table failed");
}
dev->memory_changed = false;
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 = dev->vhost_ops->vhost_set_mem_table(dev, dev->mem);
if (r < 0) {
VHOST_OPS_DEBUG("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);
}
dev->memory_changed = false;
}
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;
memory_region_ref(section->mr);
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);
memory_region_unref(section->mr);
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_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;
if (!memory_region_is_iommu(section->mr)) {
return;
}
iommu = g_malloc0(sizeof(*iommu));
end = int128_add(int128_make64(section->offset_within_region),
section->size);
end = int128_sub(end, int128_one());
iommu_notifier_init(&iommu->n, vhost_iommu_unmap_notify,
IOMMU_NOTIFIER_UNMAP,
section->offset_within_region,
int128_get64(end));
iommu->mr = section->mr;
iommu->iommu_offset = section->offset_within_address_space -
section->offset_within_region;
iommu->hdev = dev;
memory_region_register_iommu_notifier(section->mr, &iommu->n);
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 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 = dev->vhost_ops->vhost_set_vring_addr(dev, &addr);
if (r < 0) {
VHOST_OPS_DEBUG("vhost_set_vring_addr failed");
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 |= 0x1ULL << VHOST_F_LOG_ALL;
}
r = dev->vhost_ops->vhost_set_features(dev, features);
if (r < 0) {
VHOST_OPS_DEBUG("vhost_set_features failed");
}
return r < 0 ? -errno : 0;
}
static int vhost_dev_set_log(struct vhost_dev *dev, bool enable_log)
{
int r, i, idx;
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);
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);
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, 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;
}
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) {
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,
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;
}
#ifdef HOST_WORDS_BIGENDIAN
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)
{
struct vhost_vring_state s = {
.index = vhost_vq_index,
.num = is_big_endian
};
if (!dev->vhost_ops->vhost_set_vring_endian(dev, &s)) {
return 0;
}
VHOST_OPS_DEBUG("vhost_set_vring_endian failed");
if (errno == ENOTTY) {
error_report("vhost does not support cross-endian");
return -ENOSYS;
}
return -errno;
}
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();
iotlb = address_space_get_iotlb_entry(dev->vdev->dma_as,
iova, write);
if (iotlb.target_as != NULL) {
ret = vhost_memory_region_lookup(dev, iotlb.translated_addr,
&uaddr, &len);
if (ret) {
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) {
error_report("Fail to update device iotlb");
goto out;
}
}
out:
rcu_read_unlock();
return ret;
}
static 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);
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("vhost_set_vring_num failed");
return -errno;
}
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("vhost_set_vring_base failed");
return -errno;
}
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 -errno;
}
}
vq->desc_size = s = l = virtio_queue_get_desc_size(vdev, idx);
vq->desc_phys = a = virtio_queue_get_desc_addr(vdev, idx);
vq->desc = vhost_memory_map(dev, a, &l, 0);
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, 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 = vhost_memory_map(dev, a, &l, 1);
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) {
r = -errno;
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("vhost_set_vring_kick failed");
r = -errno;
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;
}
static 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;
r = dev->vhost_ops->vhost_get_vring_base(dev, &state);
if (r < 0) {
VHOST_OPS_DEBUG("vhost VQ %d ring restore failed: %d", idx, r);
} 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("vhost_set_vring_busyloop_timeout failed");
return r;
}
return 0;
}
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_fd(&vq->masked_notifier);
r = dev->vhost_ops->vhost_set_vring_call(dev, &file);
if (r) {
VHOST_OPS_DEBUG("vhost_set_vring_call failed");
r = -errno;
goto fail_call;
}
vq->dev = dev;
return 0;
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);
}
int vhost_dev_init(struct vhost_dev *hdev, void *opaque,
VhostBackendType backend_type, uint32_t busyloop_timeout)
{
uint64_t features;
int i, r, n_initialized_vqs = 0;
Error *local_err = NULL;
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);
if (r < 0) {
goto fail;
}
if (used_memslots > hdev->vhost_ops->vhost_backend_memslots_limit(hdev)) {
error_report("vhost backend memory slots limit is less"
" than current number of present memory slots");
r = -1;
goto fail;
}
r = hdev->vhost_ops->vhost_set_owner(hdev);
if (r < 0) {
VHOST_OPS_DEBUG("vhost_set_owner failed");
goto fail;
}
r = hdev->vhost_ops->vhost_get_features(hdev, &features);
if (r < 0) {
VHOST_OPS_DEBUG("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) {
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) {
goto fail_busyloop;
}
}
}
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->iommu_listener = (MemoryListener) {
.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_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, &local_err);
if (local_err) {
error_report_err(local_err);
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;
hdev->memory_changed = false;
memory_listener_register(&hdev->memory_listener, &address_space_memory);
QLIST_INSERT_HEAD(&vhost_devices, hdev, entry);
return 0;
fail_busyloop:
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;
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);
for (i = 0; i < hdev->n_mem_sections; ++i) {
MemoryRegionSection *section = &hdev->mem_sections[i];
memory_region_unref(section->mr);
}
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_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_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_fd(&hdev->vqs[index].masked_notifier);
} else {
file.fd = event_notifier_get_fd(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("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++;
}
}
/* Host notifiers must be enabled at this point. */
int vhost_dev_start(struct vhost_dev *hdev, VirtIODevice *vdev)
{
int i, r;
/* should only be called after backend is connected */
assert(hdev->vhost_ops);
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("vhost_set_mem_table failed");
r = -errno;
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("vhost_set_log_base failed");
r = -errno;
goto fail_log;
}
}
if (vhost_dev_has_iommu(hdev)) {
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_log:
vhost_log_put(hdev, false);
fail_vq:
while (--i >= 0) {
vhost_virtqueue_stop(hdev,
vdev,
hdev->vqs + i,
hdev->vq_index + i);
}
i = hdev->nvqs;
fail_mem:
fail_features:
hdev->started = false;
return r;
}
/* Host notifiers must be enabled at this point. */
void vhost_dev_stop(struct vhost_dev *hdev, VirtIODevice *vdev)
{
int i;
/* should only be called after backend is connected */
assert(hdev->vhost_ops);
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)) {
hdev->vhost_ops->vhost_set_iotlb_callback(hdev, false);
memory_listener_unregister(&hdev->iommu_listener);
}
vhost_log_put(hdev, true);
hdev->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 -1;
}
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