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qemu/hw/virtio/vhost.c
Kevin Wolf 2c66de61f8 vdpa-dev: Fix initialisation order to restore VDUSE compatibility 
VDUSE requires that virtqueues are first enabled before the DRIVER_OK
status flag is set; with the current API of the kernel module, it is
impossible to enable the opposite order in our block export code because
userspace is not notified when a virtqueue is enabled.

This requirement also mathces the normal initialisation order as done by
the generic vhost code in QEMU. However, commit 6c482547 accidentally
changed the order for vdpa-dev and broke access to VDUSE devices with
this.

This changes vdpa-dev to use the normal order again and use the standard
vhost callback .vhost_set_vring_enable for this. VDUSE devices can be
used with vdpa-dev again after this fix.

vhost_net intentionally avoided enabling the vrings for vdpa and does
this manually later while it does enable them for other vhost backends.
Reflect this in the vhost_net code and return early for vdpa, so that
the behaviour doesn't change for this device.

Cc: qemu-stable@nongnu.org
Fixes: 6c4825476a ('vdpa: move vhost_vdpa_set_vring_ready to the caller')
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20240315155949.86066-1-kwolf@redhat.com>
Reviewed-by: Eugenio Pérez <eperezma@redhat.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2024-03-26 14:21:26 +01:00

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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 "qemu/atomic.h"
#include "qemu/range.h"
#include "qemu/error-report.h"
#include "qemu/memfd.h"
#include "qemu/log.h"
#include "standard-headers/linux/vhost_types.h"
#include "hw/virtio/virtio-bus.h"
#include "hw/mem/memory-device.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;
/* Memslots used by backends that support private memslots (without an fd). */
static unsigned int used_memslots;
/* Memslots used by backends that only support shared memslots (with an fd). */
static unsigned int used_shared_memslots;
static QLIST_HEAD(, vhost_dev) vhost_devices =
QLIST_HEAD_INITIALIZER(vhost_devices);
unsigned int vhost_get_max_memslots(void)
{
unsigned int max = UINT_MAX;
struct vhost_dev *hdev;
QLIST_FOREACH(hdev, &vhost_devices, entry) {
max = MIN(max, hdev->vhost_ops->vhost_backend_memslots_limit(hdev));
}
return max;
}
unsigned int vhost_get_free_memslots(void)
{
unsigned int free = UINT_MAX;
struct vhost_dev *hdev;
QLIST_FOREACH(hdev, &vhost_devices, entry) {
unsigned int r = hdev->vhost_ops->vhost_backend_memslots_limit(hdev);
unsigned int cur_free;
if (hdev->vhost_ops->vhost_backend_no_private_memslots &&
hdev->vhost_ops->vhost_backend_no_private_memslots(hdev)) {
cur_free = r - used_shared_memslots;
} else {
cur_free = r - used_memslots;
}
free = MIN(free, cur_free);
}
return free;
}
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 *dev_log = dev->log->log;
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 = 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;
}
}
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 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;
}
if (vhost_dev_has_iommu(dev)) {
IOMMUTLBEntry iotlb;
hwaddr used_phys = vq->used_phys, used_size = vq->used_size;
hwaddr phys, s, offset;
while (used_size) {
rcu_read_lock();
iotlb = address_space_get_iotlb_entry(dev->vdev->dma_as,
used_phys,
true,
MEMTXATTRS_UNSPECIFIED);
rcu_read_unlock();
if (!iotlb.target_as) {
qemu_log_mask(LOG_GUEST_ERROR, "translation "
"failure for used_iova %"PRIx64"\n",
used_phys);
return -EINVAL;
}
offset = used_phys & iotlb.addr_mask;
phys = iotlb.translated_addr + offset;
/*
* Distance from start of used ring until last byte of
* IOMMU page.
*/
s = iotlb.addr_mask - offset;
/*
* Size of used ring, or of the part of it until end
* of IOMMU page. To avoid zero result, do the adding
* outside of MIN().
*/
s = MIN(s, used_size - 1) + 1;
vhost_dev_sync_region(dev, section, start_addr, end_addr, phys,
range_get_last(phys, s));
used_size -= s;
used_phys += s;
}
} else {
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 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).
*/
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;
}
/*
* Some backends (like vhost-user) can only handle memory regions
* that have an fd (can be mapped into a different process). Filter
* the ones without an fd out, if requested.
*
* TODO: we might have to limit to MAP_SHARED as well.
*/
if (memory_region_get_fd(section->mr) < 0 &&
dev->vhost_ops->vhost_backend_no_private_memslots &&
dev->vhost_ops->vhost_backend_no_private_memslots(dev)) {
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 (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;
if (dev->vhost_ops->vhost_backend_no_private_memslots &&
dev->vhost_ops->vhost_backend_no_private_memslots(dev)) {
used_shared_memslots = dev->mem->nregions;
} else {
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 && !section->unmergeable) {
/* 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 && !prev_sec->unmergeable) {
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;
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,
dev->vdev->device_iotlb_enabled ?
IOMMU_NOTIFIER_DEVIOTLB_UNMAP :
IOMMU_NOTIFIER_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;
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;
}
}
}
void vhost_toggle_device_iotlb(VirtIODevice *vdev)
{
VirtioDeviceClass *vdc = VIRTIO_DEVICE_GET_CLASS(vdev);
struct vhost_dev *dev;
struct vhost_iommu *iommu;
if (vdev->vhost_started) {
dev = vdc->get_vhost(vdev);
} else {
return;
}
QLIST_FOREACH(iommu, &dev->iommu_list, iommu_next) {
memory_region_unregister_iommu_notifier(iommu->mr, &iommu->n);
iommu->n.notifier_flags = vdev->device_iotlb_enabled ?
IOMMU_NOTIFIER_DEVIOTLB_UNMAP : IOMMU_NOTIFIER_UNMAP;
memory_region_register_iommu_notifier(iommu->mr, &iommu->n,
&error_fatal);
}
}
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 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)
{
unsigned int used, reserved, limit;
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;
}
limit = hdev->vhost_ops->vhost_backend_memslots_limit(hdev);
if (limit < MEMORY_DEVICES_SAFE_MAX_MEMSLOTS &&
memory_devices_memslot_auto_decision_active()) {
error_setg(errp, "some memory device (like virtio-mem)"
" decided how many memory slots to use based on the overall"
" number of memory slots; this vhost backend would further"
" restricts the overall number of memory slots");
error_append_hint(errp, "Try plugging this vhost backend before"
" plugging such memory devices.\n");
r = -EINVAL;
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,
.priority = MEMORY_LISTENER_PRIORITY_DEV_BACKEND
};
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_normal(&hdev->migration_blocker, errp);
if (r < 0) {
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);
/*
* The listener we registered properly updated the corresponding counter.
* So we can trust that these values are accurate.
*/
if (hdev->vhost_ops->vhost_backend_no_private_memslots &&
hdev->vhost_ops->vhost_backend_no_private_memslots(hdev)) {
used = used_shared_memslots;
} else {
used = used_memslots;
}
/*
* We assume that all reserved memslots actually require a real memslot
* in our vhost backend. This might not be true, for example, if the
* memslot would be ROM. If ever relevant, we can optimize for that --
* but we'll need additional information about the reservations.
*/
reserved = memory_devices_get_reserved_memslots();
if (used + reserved > limit) {
error_setg(errp, "vhost backend memory slots limit (%d) is less"
" than current number of used (%d) and reserved (%d)"
" memory slots for memory devices.", limit, used, reserved);
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);
}
migrate_del_blocker(&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));
}
static void vhost_dev_disable_notifiers_nvqs(struct vhost_dev *hdev,
VirtIODevice *vdev,
unsigned int nvqs)
{
BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(vdev)));
int i, r;
/*
* Batch all the host notifiers in a single transaction to avoid
* quadratic time complexity in address_space_update_ioeventfds().
*/
memory_region_transaction_begin();
for (i = 0; i < 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);
}
/*
* The transaction expects the ioeventfds to be open when it
* commits. Do it now, before the cleanup loop.
*/
memory_region_transaction_commit();
for (i = 0; i < nvqs; ++i) {
virtio_bus_cleanup_host_notifier(VIRTIO_BUS(qbus), hdev->vq_index + i);
}
virtio_device_release_ioeventfd(vdev);
}
/* 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;
/* 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");
return r;
}
/*
* Batch all the host notifiers in a single transaction to avoid
* quadratic time complexity in address_space_update_ioeventfds().
*/
memory_region_transaction_begin();
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);
memory_region_transaction_commit();
vhost_dev_disable_notifiers_nvqs(hdev, vdev, i);
return r;
}
}
memory_region_transaction_commit();
return 0;
}
/* 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)
{
vhost_dev_disable_notifiers_nvqs(hdev, vdev, hdev->nvqs);
}
/* 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) {
error_report("vhost_set_vring_call failed %d", -r);
}
}
bool vhost_config_pending(struct vhost_dev *hdev)
{
assert(hdev->vhost_ops);
if ((hdev->started == false) ||
(hdev->vhost_ops->vhost_set_config_call == NULL)) {
return false;
}
EventNotifier *notifier =
&hdev->vqs[VHOST_QUEUE_NUM_CONFIG_INR].masked_config_notifier;
return event_notifier_test_and_clear(notifier);
}
void vhost_config_mask(struct vhost_dev *hdev, VirtIODevice *vdev, bool mask)
{
int fd;
int r;
EventNotifier *notifier =
&hdev->vqs[VHOST_QUEUE_NUM_CONFIG_INR].masked_config_notifier;
EventNotifier *config_notifier = &vdev->config_notifier;
assert(hdev->vhost_ops);
if ((hdev->started == false) ||
(hdev->vhost_ops->vhost_set_config_call == NULL)) {
return;
}
if (mask) {
assert(vdev->use_guest_notifier_mask);
fd = event_notifier_get_fd(notifier);
} else {
fd = event_notifier_get_fd(config_notifier);
}
r = hdev->vhost_ops->vhost_set_config_call(hdev, fd);
if (r < 0) {
error_report("vhost_set_config_call failed %d", -r);
}
}
static void vhost_stop_config_intr(struct vhost_dev *dev)
{
int fd = -1;
assert(dev->vhost_ops);
if (dev->vhost_ops->vhost_set_config_call) {
dev->vhost_ops->vhost_set_config_call(dev, fd);
}
}
static void vhost_start_config_intr(struct vhost_dev *dev)
{
int r;
assert(dev->vhost_ops);
int fd = event_notifier_get_fd(&dev->vdev->config_notifier);
if (dev->vhost_ops->vhost_set_config_call) {
r = dev->vhost_ops->vhost_set_config_call(dev, fd);
if (!r) {
event_notifier_set(&dev->vdev->config_notifier);
}
}
}
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.
*
* If @vrings is true, this function will enable all vrings before starting the
* device. If it is false, the vring initialization is left to be done by the
* caller.
*/
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;
}
}
r = event_notifier_init(
&hdev->vqs[VHOST_QUEUE_NUM_CONFIG_INR].masked_config_notifier, 0);
if (r < 0) {
VHOST_OPS_DEBUG(r, "event_notifier_init failed");
goto fail_vq;
}
event_notifier_test_and_clear(
&hdev->vqs[VHOST_QUEUE_NUM_CONFIG_INR].masked_config_notifier);
if (!vdev->use_guest_notifier_mask) {
vhost_config_mask(hdev, vdev, true);
}
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);
}
}
vhost_start_config_intr(hdev);
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:
if (vhost_dev_has_iommu(hdev)) {
memory_listener_unregister(&hdev->iommu_listener);
}
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);
event_notifier_test_and_clear(
&hdev->vqs[VHOST_QUEUE_NUM_CONFIG_INR].masked_config_notifier);
event_notifier_test_and_clear(&vdev->config_notifier);
event_notifier_cleanup(
&hdev->vqs[VHOST_QUEUE_NUM_CONFIG_INR].masked_config_notifier);
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 (hdev->vhost_ops->vhost_reset_status) {
hdev->vhost_ops->vhost_reset_status(hdev);
}
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_stop_config_intr(hdev);
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;
}
int vhost_reset_device(struct vhost_dev *hdev)
{
if (hdev->vhost_ops->vhost_reset_device) {
return hdev->vhost_ops->vhost_reset_device(hdev);
}
return -ENOSYS;
}
bool vhost_supports_device_state(struct vhost_dev *dev)
{
if (dev->vhost_ops->vhost_supports_device_state) {
return dev->vhost_ops->vhost_supports_device_state(dev);
}
return false;
}
int vhost_set_device_state_fd(struct vhost_dev *dev,
VhostDeviceStateDirection direction,
VhostDeviceStatePhase phase,
int fd,
int *reply_fd,
Error **errp)
{
if (dev->vhost_ops->vhost_set_device_state_fd) {
return dev->vhost_ops->vhost_set_device_state_fd(dev, direction, phase,
fd, reply_fd, errp);
}
error_setg(errp,
"vhost transport does not support migration state transfer");
return -ENOSYS;
}
int vhost_check_device_state(struct vhost_dev *dev, Error **errp)
{
if (dev->vhost_ops->vhost_check_device_state) {
return dev->vhost_ops->vhost_check_device_state(dev, errp);
}
error_setg(errp,
"vhost transport does not support migration state transfer");
return -ENOSYS;
}
int vhost_save_backend_state(struct vhost_dev *dev, QEMUFile *f, Error **errp)
{
ERRP_GUARD();
/* Maximum chunk size in which to transfer the state */
const size_t chunk_size = 1 * 1024 * 1024;
g_autofree void *transfer_buf = NULL;
g_autoptr(GError) g_err = NULL;
int pipe_fds[2], read_fd = -1, write_fd = -1, reply_fd = -1;
int ret;
/* [0] for reading (our end), [1] for writing (back-end's end) */
if (!g_unix_open_pipe(pipe_fds, FD_CLOEXEC, &g_err)) {
error_setg(errp, "Failed to set up state transfer pipe: %s",
g_err->message);
ret = -EINVAL;
goto fail;
}
read_fd = pipe_fds[0];
write_fd = pipe_fds[1];
/*
* VHOST_TRANSFER_STATE_PHASE_STOPPED means the device must be stopped.
* Ideally, it is suspended, but SUSPEND/RESUME currently do not exist for
* vhost-user, so just check that it is stopped at all.
*/
assert(!dev->started);
/* Transfer ownership of write_fd to the back-end */
ret = vhost_set_device_state_fd(dev,
VHOST_TRANSFER_STATE_DIRECTION_SAVE,
VHOST_TRANSFER_STATE_PHASE_STOPPED,
write_fd,
&reply_fd,
errp);
if (ret < 0) {
error_prepend(errp, "Failed to initiate state transfer: ");
goto fail;
}
/* If the back-end wishes to use a different pipe, switch over */
if (reply_fd >= 0) {
close(read_fd);
read_fd = reply_fd;
}
transfer_buf = g_malloc(chunk_size);
while (true) {
ssize_t read_ret;
read_ret = RETRY_ON_EINTR(read(read_fd, transfer_buf, chunk_size));
if (read_ret < 0) {
ret = -errno;
error_setg_errno(errp, -ret, "Failed to receive state");
goto fail;
}
assert(read_ret <= chunk_size);
qemu_put_be32(f, read_ret);
if (read_ret == 0) {
/* EOF */
break;
}
qemu_put_buffer(f, transfer_buf, read_ret);
}
/*
* Back-end will not really care, but be clean and close our end of the pipe
* before inquiring the back-end about whether transfer was successful
*/
close(read_fd);
read_fd = -1;
/* Also, verify that the device is still stopped */
assert(!dev->started);
ret = vhost_check_device_state(dev, errp);
if (ret < 0) {
goto fail;
}
ret = 0;
fail:
if (read_fd >= 0) {
close(read_fd);
}
return ret;
}
int vhost_load_backend_state(struct vhost_dev *dev, QEMUFile *f, Error **errp)
{
ERRP_GUARD();
size_t transfer_buf_size = 0;
g_autofree void *transfer_buf = NULL;
g_autoptr(GError) g_err = NULL;
int pipe_fds[2], read_fd = -1, write_fd = -1, reply_fd = -1;
int ret;
/* [0] for reading (back-end's end), [1] for writing (our end) */
if (!g_unix_open_pipe(pipe_fds, FD_CLOEXEC, &g_err)) {
error_setg(errp, "Failed to set up state transfer pipe: %s",
g_err->message);
ret = -EINVAL;
goto fail;
}
read_fd = pipe_fds[0];
write_fd = pipe_fds[1];
/*
* VHOST_TRANSFER_STATE_PHASE_STOPPED means the device must be stopped.
* Ideally, it is suspended, but SUSPEND/RESUME currently do not exist for
* vhost-user, so just check that it is stopped at all.
*/
assert(!dev->started);
/* Transfer ownership of read_fd to the back-end */
ret = vhost_set_device_state_fd(dev,
VHOST_TRANSFER_STATE_DIRECTION_LOAD,
VHOST_TRANSFER_STATE_PHASE_STOPPED,
read_fd,
&reply_fd,
errp);
if (ret < 0) {
error_prepend(errp, "Failed to initiate state transfer: ");
goto fail;
}
/* If the back-end wishes to use a different pipe, switch over */
if (reply_fd >= 0) {
close(write_fd);
write_fd = reply_fd;
}
while (true) {
size_t this_chunk_size = qemu_get_be32(f);
ssize_t write_ret;
const uint8_t *transfer_pointer;
if (this_chunk_size == 0) {
/* End of state */
break;
}
if (transfer_buf_size < this_chunk_size) {
transfer_buf = g_realloc(transfer_buf, this_chunk_size);
transfer_buf_size = this_chunk_size;
}
if (qemu_get_buffer(f, transfer_buf, this_chunk_size) <
this_chunk_size)
{
error_setg(errp, "Failed to read state");
ret = -EINVAL;
goto fail;
}
transfer_pointer = transfer_buf;
while (this_chunk_size > 0) {
write_ret = RETRY_ON_EINTR(
write(write_fd, transfer_pointer, this_chunk_size)
);
if (write_ret < 0) {
ret = -errno;
error_setg_errno(errp, -ret, "Failed to send state");
goto fail;
} else if (write_ret == 0) {
error_setg(errp, "Failed to send state: Connection is closed");
ret = -ECONNRESET;
goto fail;
}
assert(write_ret <= this_chunk_size);
this_chunk_size -= write_ret;
transfer_pointer += write_ret;
}
}
/*
* Close our end, thus ending transfer, before inquiring the back-end about
* whether transfer was successful
*/
close(write_fd);
write_fd = -1;
/* Also, verify that the device is still stopped */
assert(!dev->started);
ret = vhost_check_device_state(dev, errp);
if (ret < 0) {
goto fail;
}
ret = 0;
fail:
if (write_fd >= 0) {
close(write_fd);
}
return ret;
}
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