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38738f7dbb
qemu-e2k/hw/virtio/virtio.c
Stefan Hajnoczi 38738f7dbb virtio-scsi: don't waste CPU polling the event virtqueue 
The virtio-scsi event virtqueue is not emptied by its handler function.
This is typical for rx virtqueues where the device uses buffers when
some event occurs (e.g. a packet is received, an error condition
happens, etc).

Polling non-empty virtqueues wastes CPU cycles. We are not waiting for
new buffers to become available, we are waiting for an event to occur,
so it's a misuse of CPU resources to poll for buffers.

Introduce the new virtio_queue_aio_attach_host_notifier_no_poll() API,
which is identical to virtio_queue_aio_attach_host_notifier() except
that it does not poll the virtqueue.

Before this patch the following command-line consumed 100% CPU in the
IOThread polling and calling virtio_scsi_handle_event():

  $ qemu-system-x86_64 -M accel=kvm -m 1G -cpu host \
      --object iothread,id=iothread0 \
      --device virtio-scsi-pci,iothread=iothread0 \
      --blockdev file,filename=test.img,aio=native,cache.direct=on,node-name=drive0 \
      --device scsi-hd,drive=drive0

After this patch CPU is no longer wasted.

Reported-by: Nir Soffer <nsoffer@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Tested-by: Nir Soffer <nsoffer@redhat.com>
Message-id: 20220427143541.119567-3-stefanha@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2022-05-09 10:45:04 +01:00

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/*
* Virtio Support
*
* Copyright IBM, Corp. 2007
*
* Authors:
* Anthony Liguori <aliguori@us.ibm.com>
*
* This work is licensed under the terms of the GNU GPL, version 2. See
* the COPYING file in the top-level directory.
*
*/
#include "qemu/osdep.h"
#include "qapi/error.h"
#include "cpu.h"
#include "trace.h"
#include "qemu/error-report.h"
#include "qemu/log.h"
#include "qemu/main-loop.h"
#include "qemu/module.h"
#include "hw/virtio/virtio.h"
#include "migration/qemu-file-types.h"
#include "qemu/atomic.h"
#include "hw/virtio/virtio-bus.h"
#include "hw/qdev-properties.h"
#include "hw/virtio/virtio-access.h"
#include "sysemu/dma.h"
#include "sysemu/runstate.h"
#include "standard-headers/linux/virtio_ids.h"
/*
* The alignment to use between consumer and producer parts of vring.
* x86 pagesize again. This is the default, used by transports like PCI
* which don't provide a means for the guest to tell the host the alignment.
*/
#define VIRTIO_PCI_VRING_ALIGN 4096
typedef struct VRingDesc
{
uint64_t addr;
uint32_t len;
uint16_t flags;
uint16_t next;
} VRingDesc;
typedef struct VRingPackedDesc {
uint64_t addr;
uint32_t len;
uint16_t id;
uint16_t flags;
} VRingPackedDesc;
typedef struct VRingAvail
{
uint16_t flags;
uint16_t idx;
uint16_t ring[];
} VRingAvail;
typedef struct VRingUsedElem
{
uint32_t id;
uint32_t len;
} VRingUsedElem;
typedef struct VRingUsed
{
uint16_t flags;
uint16_t idx;
VRingUsedElem ring[];
} VRingUsed;
typedef struct VRingMemoryRegionCaches {
struct rcu_head rcu;
MemoryRegionCache desc;
MemoryRegionCache avail;
MemoryRegionCache used;
} VRingMemoryRegionCaches;
typedef struct VRing
{
unsigned int num;
unsigned int num_default;
unsigned int align;
hwaddr desc;
hwaddr avail;
hwaddr used;
VRingMemoryRegionCaches *caches;
} VRing;
typedef struct VRingPackedDescEvent {
uint16_t off_wrap;
uint16_t flags;
} VRingPackedDescEvent ;
struct VirtQueue
{
VRing vring;
VirtQueueElement *used_elems;
/* Next head to pop */
uint16_t last_avail_idx;
bool last_avail_wrap_counter;
/* Last avail_idx read from VQ. */
uint16_t shadow_avail_idx;
bool shadow_avail_wrap_counter;
uint16_t used_idx;
bool used_wrap_counter;
/* Last used index value we have signalled on */
uint16_t signalled_used;
/* Last used index value we have signalled on */
bool signalled_used_valid;
/* Notification enabled? */
bool notification;
uint16_t queue_index;
unsigned int inuse;
uint16_t vector;
VirtIOHandleOutput handle_output;
VirtIODevice *vdev;
EventNotifier guest_notifier;
EventNotifier host_notifier;
bool host_notifier_enabled;
QLIST_ENTRY(VirtQueue) node;
};
/* Called within call_rcu(). */
static void virtio_free_region_cache(VRingMemoryRegionCaches *caches)
{
assert(caches != NULL);
address_space_cache_destroy(&caches->desc);
address_space_cache_destroy(&caches->avail);
address_space_cache_destroy(&caches->used);
g_free(caches);
}
static void virtio_virtqueue_reset_region_cache(struct VirtQueue *vq)
{
VRingMemoryRegionCaches *caches;
caches = qatomic_read(&vq->vring.caches);
qatomic_rcu_set(&vq->vring.caches, NULL);
if (caches) {
call_rcu(caches, virtio_free_region_cache, rcu);
}
}
static void virtio_init_region_cache(VirtIODevice *vdev, int n)
{
VirtQueue *vq = &vdev->vq[n];
VRingMemoryRegionCaches *old = vq->vring.caches;
VRingMemoryRegionCaches *new = NULL;
hwaddr addr, size;
int64_t len;
bool packed;
addr = vq->vring.desc;
if (!addr) {
goto out_no_cache;
}
new = g_new0(VRingMemoryRegionCaches, 1);
size = virtio_queue_get_desc_size(vdev, n);
packed = virtio_vdev_has_feature(vq->vdev, VIRTIO_F_RING_PACKED) ?
true : false;
len = address_space_cache_init(&new->desc, vdev->dma_as,
addr, size, packed);
if (len < size) {
virtio_error(vdev, "Cannot map desc");
goto err_desc;
}
size = virtio_queue_get_used_size(vdev, n);
len = address_space_cache_init(&new->used, vdev->dma_as,
vq->vring.used, size, true);
if (len < size) {
virtio_error(vdev, "Cannot map used");
goto err_used;
}
size = virtio_queue_get_avail_size(vdev, n);
len = address_space_cache_init(&new->avail, vdev->dma_as,
vq->vring.avail, size, false);
if (len < size) {
virtio_error(vdev, "Cannot map avail");
goto err_avail;
}
qatomic_rcu_set(&vq->vring.caches, new);
if (old) {
call_rcu(old, virtio_free_region_cache, rcu);
}
return;
err_avail:
address_space_cache_destroy(&new->avail);
err_used:
address_space_cache_destroy(&new->used);
err_desc:
address_space_cache_destroy(&new->desc);
out_no_cache:
g_free(new);
virtio_virtqueue_reset_region_cache(vq);
}
/* virt queue functions */
void virtio_queue_update_rings(VirtIODevice *vdev, int n)
{
VRing *vring = &vdev->vq[n].vring;
if (!vring->num || !vring->desc || !vring->align) {
/* not yet setup -> nothing to do */
return;
}
vring->avail = vring->desc + vring->num * sizeof(VRingDesc);
vring->used = vring_align(vring->avail +
offsetof(VRingAvail, ring[vring->num]),
vring->align);
virtio_init_region_cache(vdev, n);
}
/* Called within rcu_read_lock(). */
static void vring_split_desc_read(VirtIODevice *vdev, VRingDesc *desc,
MemoryRegionCache *cache, int i)
{
address_space_read_cached(cache, i * sizeof(VRingDesc),
desc, sizeof(VRingDesc));
virtio_tswap64s(vdev, &desc->addr);
virtio_tswap32s(vdev, &desc->len);
virtio_tswap16s(vdev, &desc->flags);
virtio_tswap16s(vdev, &desc->next);
}
static void vring_packed_event_read(VirtIODevice *vdev,
MemoryRegionCache *cache,
VRingPackedDescEvent *e)
{
hwaddr off_off = offsetof(VRingPackedDescEvent, off_wrap);
hwaddr off_flags = offsetof(VRingPackedDescEvent, flags);
e->flags = virtio_lduw_phys_cached(vdev, cache, off_flags);
/* Make sure flags is seen before off_wrap */
smp_rmb();
e->off_wrap = virtio_lduw_phys_cached(vdev, cache, off_off);
virtio_tswap16s(vdev, &e->flags);
}
static void vring_packed_off_wrap_write(VirtIODevice *vdev,
MemoryRegionCache *cache,
uint16_t off_wrap)
{
hwaddr off = offsetof(VRingPackedDescEvent, off_wrap);
virtio_stw_phys_cached(vdev, cache, off, off_wrap);
address_space_cache_invalidate(cache, off, sizeof(off_wrap));
}
static void vring_packed_flags_write(VirtIODevice *vdev,
MemoryRegionCache *cache, uint16_t flags)
{
hwaddr off = offsetof(VRingPackedDescEvent, flags);
virtio_stw_phys_cached(vdev, cache, off, flags);
address_space_cache_invalidate(cache, off, sizeof(flags));
}
/* Called within rcu_read_lock(). */
static VRingMemoryRegionCaches *vring_get_region_caches(struct VirtQueue *vq)
{
return qatomic_rcu_read(&vq->vring.caches);
}
/* Called within rcu_read_lock(). */
static inline uint16_t vring_avail_flags(VirtQueue *vq)
{
VRingMemoryRegionCaches *caches = vring_get_region_caches(vq);
hwaddr pa = offsetof(VRingAvail, flags);
if (!caches) {
return 0;
}
return virtio_lduw_phys_cached(vq->vdev, &caches->avail, pa);
}
/* Called within rcu_read_lock(). */
static inline uint16_t vring_avail_idx(VirtQueue *vq)
{
VRingMemoryRegionCaches *caches = vring_get_region_caches(vq);
hwaddr pa = offsetof(VRingAvail, idx);
if (!caches) {
return 0;
}
vq->shadow_avail_idx = virtio_lduw_phys_cached(vq->vdev, &caches->avail, pa);
return vq->shadow_avail_idx;
}
/* Called within rcu_read_lock(). */
static inline uint16_t vring_avail_ring(VirtQueue *vq, int i)
{
VRingMemoryRegionCaches *caches = vring_get_region_caches(vq);
hwaddr pa = offsetof(VRingAvail, ring[i]);
if (!caches) {
return 0;
}
return virtio_lduw_phys_cached(vq->vdev, &caches->avail, pa);
}
/* Called within rcu_read_lock(). */
static inline uint16_t vring_get_used_event(VirtQueue *vq)
{
return vring_avail_ring(vq, vq->vring.num);
}
/* Called within rcu_read_lock(). */
static inline void vring_used_write(VirtQueue *vq, VRingUsedElem *uelem,
int i)
{
VRingMemoryRegionCaches *caches = vring_get_region_caches(vq);
hwaddr pa = offsetof(VRingUsed, ring[i]);
if (!caches) {
return;
}
virtio_tswap32s(vq->vdev, &uelem->id);
virtio_tswap32s(vq->vdev, &uelem->len);
address_space_write_cached(&caches->used, pa, uelem, sizeof(VRingUsedElem));
address_space_cache_invalidate(&caches->used, pa, sizeof(VRingUsedElem));
}
/* Called within rcu_read_lock(). */
static uint16_t vring_used_idx(VirtQueue *vq)
{
VRingMemoryRegionCaches *caches = vring_get_region_caches(vq);
hwaddr pa = offsetof(VRingUsed, idx);
if (!caches) {
return 0;
}
return virtio_lduw_phys_cached(vq->vdev, &caches->used, pa);
}
/* Called within rcu_read_lock(). */
static inline void vring_used_idx_set(VirtQueue *vq, uint16_t val)
{
VRingMemoryRegionCaches *caches = vring_get_region_caches(vq);
hwaddr pa = offsetof(VRingUsed, idx);
if (caches) {
virtio_stw_phys_cached(vq->vdev, &caches->used, pa, val);
address_space_cache_invalidate(&caches->used, pa, sizeof(val));
}
vq->used_idx = val;
}
/* Called within rcu_read_lock(). */
static inline void vring_used_flags_set_bit(VirtQueue *vq, int mask)
{
VRingMemoryRegionCaches *caches = vring_get_region_caches(vq);
VirtIODevice *vdev = vq->vdev;
hwaddr pa = offsetof(VRingUsed, flags);
uint16_t flags;
if (!caches) {
return;
}
flags = virtio_lduw_phys_cached(vq->vdev, &caches->used, pa);
virtio_stw_phys_cached(vdev, &caches->used, pa, flags | mask);
address_space_cache_invalidate(&caches->used, pa, sizeof(flags));
}
/* Called within rcu_read_lock(). */
static inline void vring_used_flags_unset_bit(VirtQueue *vq, int mask)
{
VRingMemoryRegionCaches *caches = vring_get_region_caches(vq);
VirtIODevice *vdev = vq->vdev;
hwaddr pa = offsetof(VRingUsed, flags);
uint16_t flags;
if (!caches) {
return;
}
flags = virtio_lduw_phys_cached(vq->vdev, &caches->used, pa);
virtio_stw_phys_cached(vdev, &caches->used, pa, flags & ~mask);
address_space_cache_invalidate(&caches->used, pa, sizeof(flags));
}
/* Called within rcu_read_lock(). */
static inline void vring_set_avail_event(VirtQueue *vq, uint16_t val)
{
VRingMemoryRegionCaches *caches;
hwaddr pa;
if (!vq->notification) {
return;
}
caches = vring_get_region_caches(vq);
if (!caches) {
return;
}
pa = offsetof(VRingUsed, ring[vq->vring.num]);
virtio_stw_phys_cached(vq->vdev, &caches->used, pa, val);
address_space_cache_invalidate(&caches->used, pa, sizeof(val));
}
static void virtio_queue_split_set_notification(VirtQueue *vq, int enable)
{
RCU_READ_LOCK_GUARD();
if (virtio_vdev_has_feature(vq->vdev, VIRTIO_RING_F_EVENT_IDX)) {
vring_set_avail_event(vq, vring_avail_idx(vq));
} else if (enable) {
vring_used_flags_unset_bit(vq, VRING_USED_F_NO_NOTIFY);
} else {
vring_used_flags_set_bit(vq, VRING_USED_F_NO_NOTIFY);
}
if (enable) {
/* Expose avail event/used flags before caller checks the avail idx. */
smp_mb();
}
}
static void virtio_queue_packed_set_notification(VirtQueue *vq, int enable)
{
uint16_t off_wrap;
VRingPackedDescEvent e;
VRingMemoryRegionCaches *caches;
RCU_READ_LOCK_GUARD();
caches = vring_get_region_caches(vq);
if (!caches) {
return;
}
vring_packed_event_read(vq->vdev, &caches->used, &e);
if (!enable) {
e.flags = VRING_PACKED_EVENT_FLAG_DISABLE;
} else if (virtio_vdev_has_feature(vq->vdev, VIRTIO_RING_F_EVENT_IDX)) {
off_wrap = vq->shadow_avail_idx | vq->shadow_avail_wrap_counter << 15;
vring_packed_off_wrap_write(vq->vdev, &caches->used, off_wrap);
/* Make sure off_wrap is wrote before flags */
smp_wmb();
e.flags = VRING_PACKED_EVENT_FLAG_DESC;
} else {
e.flags = VRING_PACKED_EVENT_FLAG_ENABLE;
}
vring_packed_flags_write(vq->vdev, &caches->used, e.flags);
if (enable) {
/* Expose avail event/used flags before caller checks the avail idx. */
smp_mb();
}
}
bool virtio_queue_get_notification(VirtQueue *vq)
{
return vq->notification;
}
void virtio_queue_set_notification(VirtQueue *vq, int enable)
{
vq->notification = enable;
if (!vq->vring.desc) {
return;
}
if (virtio_vdev_has_feature(vq->vdev, VIRTIO_F_RING_PACKED)) {
virtio_queue_packed_set_notification(vq, enable);
} else {
virtio_queue_split_set_notification(vq, enable);
}
}
int virtio_queue_ready(VirtQueue *vq)
{
return vq->vring.avail != 0;
}
static void vring_packed_desc_read_flags(VirtIODevice *vdev,
uint16_t *flags,
MemoryRegionCache *cache,
int i)
{
hwaddr off = i * sizeof(VRingPackedDesc) + offsetof(VRingPackedDesc, flags);
*flags = virtio_lduw_phys_cached(vdev, cache, off);
}
static void vring_packed_desc_read(VirtIODevice *vdev,
VRingPackedDesc *desc,
MemoryRegionCache *cache,
int i, bool strict_order)
{
hwaddr off = i * sizeof(VRingPackedDesc);
vring_packed_desc_read_flags(vdev, &desc->flags, cache, i);
if (strict_order) {
/* Make sure flags is read before the rest fields. */
smp_rmb();
}
address_space_read_cached(cache, off + offsetof(VRingPackedDesc, addr),
&desc->addr, sizeof(desc->addr));
address_space_read_cached(cache, off + offsetof(VRingPackedDesc, id),
&desc->id, sizeof(desc->id));
address_space_read_cached(cache, off + offsetof(VRingPackedDesc, len),
&desc->len, sizeof(desc->len));
virtio_tswap64s(vdev, &desc->addr);
virtio_tswap16s(vdev, &desc->id);
virtio_tswap32s(vdev, &desc->len);
}
static void vring_packed_desc_write_data(VirtIODevice *vdev,
VRingPackedDesc *desc,
MemoryRegionCache *cache,
int i)
{
hwaddr off_id = i * sizeof(VRingPackedDesc) +
offsetof(VRingPackedDesc, id);
hwaddr off_len = i * sizeof(VRingPackedDesc) +
offsetof(VRingPackedDesc, len);
virtio_tswap32s(vdev, &desc->len);
virtio_tswap16s(vdev, &desc->id);
address_space_write_cached(cache, off_id, &desc->id, sizeof(desc->id));
address_space_cache_invalidate(cache, off_id, sizeof(desc->id));
address_space_write_cached(cache, off_len, &desc->len, sizeof(desc->len));
address_space_cache_invalidate(cache, off_len, sizeof(desc->len));
}
static void vring_packed_desc_write_flags(VirtIODevice *vdev,
VRingPackedDesc *desc,
MemoryRegionCache *cache,
int i)
{
hwaddr off = i * sizeof(VRingPackedDesc) + offsetof(VRingPackedDesc, flags);
virtio_stw_phys_cached(vdev, cache, off, desc->flags);
address_space_cache_invalidate(cache, off, sizeof(desc->flags));
}
static void vring_packed_desc_write(VirtIODevice *vdev,
VRingPackedDesc *desc,
MemoryRegionCache *cache,
int i, bool strict_order)
{
vring_packed_desc_write_data(vdev, desc, cache, i);
if (strict_order) {
/* Make sure data is wrote before flags. */
smp_wmb();
}
vring_packed_desc_write_flags(vdev, desc, cache, i);
}
static inline bool is_desc_avail(uint16_t flags, bool wrap_counter)
{
bool avail, used;
avail = !!(flags & (1 << VRING_PACKED_DESC_F_AVAIL));
used = !!(flags & (1 << VRING_PACKED_DESC_F_USED));
return (avail != used) && (avail == wrap_counter);
}
/* Fetch avail_idx from VQ memory only when we really need to know if
* guest has added some buffers.
* Called within rcu_read_lock(). */
static int virtio_queue_empty_rcu(VirtQueue *vq)
{
if (virtio_device_disabled(vq->vdev)) {
return 1;
}
if (unlikely(!vq->vring.avail)) {
return 1;
}
if (vq->shadow_avail_idx != vq->last_avail_idx) {
return 0;
}
return vring_avail_idx(vq) == vq->last_avail_idx;
}
static int virtio_queue_split_empty(VirtQueue *vq)
{
bool empty;
if (virtio_device_disabled(vq->vdev)) {
return 1;
}
if (unlikely(!vq->vring.avail)) {
return 1;
}
if (vq->shadow_avail_idx != vq->last_avail_idx) {
return 0;
}
RCU_READ_LOCK_GUARD();
empty = vring_avail_idx(vq) == vq->last_avail_idx;
return empty;
}
/* Called within rcu_read_lock(). */
static int virtio_queue_packed_empty_rcu(VirtQueue *vq)
{
struct VRingPackedDesc desc;
VRingMemoryRegionCaches *cache;
if (unlikely(!vq->vring.desc)) {
return 1;
}
cache = vring_get_region_caches(vq);
if (!cache) {
return 1;
}
vring_packed_desc_read_flags(vq->vdev, &desc.flags, &cache->desc,
vq->last_avail_idx);
return !is_desc_avail(desc.flags, vq->last_avail_wrap_counter);
}
static int virtio_queue_packed_empty(VirtQueue *vq)
{
RCU_READ_LOCK_GUARD();
return virtio_queue_packed_empty_rcu(vq);
}
int virtio_queue_empty(VirtQueue *vq)
{
if (virtio_vdev_has_feature(vq->vdev, VIRTIO_F_RING_PACKED)) {
return virtio_queue_packed_empty(vq);
} else {
return virtio_queue_split_empty(vq);
}
}
static void virtqueue_unmap_sg(VirtQueue *vq, const VirtQueueElement *elem,
unsigned int len)
{
AddressSpace *dma_as = vq->vdev->dma_as;
unsigned int offset;
int i;
offset = 0;
for (i = 0; i < elem->in_num; i++) {
size_t size = MIN(len - offset, elem->in_sg[i].iov_len);
dma_memory_unmap(dma_as, elem->in_sg[i].iov_base,
elem->in_sg[i].iov_len,
DMA_DIRECTION_FROM_DEVICE, size);
offset += size;
}
for (i = 0; i < elem->out_num; i++)
dma_memory_unmap(dma_as, elem->out_sg[i].iov_base,
elem->out_sg[i].iov_len,
DMA_DIRECTION_TO_DEVICE,
elem->out_sg[i].iov_len);
}
/* virtqueue_detach_element:
* @vq: The #VirtQueue
* @elem: The #VirtQueueElement
* @len: number of bytes written
*
* Detach the element from the virtqueue. This function is suitable for device
* reset or other situations where a #VirtQueueElement is simply freed and will
* not be pushed or discarded.
*/
void virtqueue_detach_element(VirtQueue *vq, const VirtQueueElement *elem,
unsigned int len)
{
vq->inuse -= elem->ndescs;
virtqueue_unmap_sg(vq, elem, len);
}
static void virtqueue_split_rewind(VirtQueue *vq, unsigned int num)
{
vq->last_avail_idx -= num;
}
static void virtqueue_packed_rewind(VirtQueue *vq, unsigned int num)
{
if (vq->last_avail_idx < num) {
vq->last_avail_idx = vq->vring.num + vq->last_avail_idx - num;
vq->last_avail_wrap_counter ^= 1;
} else {
vq->last_avail_idx -= num;
}
}
/* virtqueue_unpop:
* @vq: The #VirtQueue
* @elem: The #VirtQueueElement
* @len: number of bytes written
*
* Pretend the most recent element wasn't popped from the virtqueue. The next
* call to virtqueue_pop() will refetch the element.
*/
void virtqueue_unpop(VirtQueue *vq, const VirtQueueElement *elem,
unsigned int len)
{
if (virtio_vdev_has_feature(vq->vdev, VIRTIO_F_RING_PACKED)) {
virtqueue_packed_rewind(vq, 1);
} else {
virtqueue_split_rewind(vq, 1);
}
virtqueue_detach_element(vq, elem, len);
}
/* virtqueue_rewind:
* @vq: The #VirtQueue
* @num: Number of elements to push back
*
* Pretend that elements weren't popped from the virtqueue. The next
* virtqueue_pop() will refetch the oldest element.
*
* Use virtqueue_unpop() instead if you have a VirtQueueElement.
*
* Returns: true on success, false if @num is greater than the number of in use
* elements.
*/
bool virtqueue_rewind(VirtQueue *vq, unsigned int num)
{
if (num > vq->inuse) {
return false;
}
vq->inuse -= num;
if (virtio_vdev_has_feature(vq->vdev, VIRTIO_F_RING_PACKED)) {
virtqueue_packed_rewind(vq, num);
} else {
virtqueue_split_rewind(vq, num);
}
return true;
}
static void virtqueue_split_fill(VirtQueue *vq, const VirtQueueElement *elem,
unsigned int len, unsigned int idx)
{
VRingUsedElem uelem;
if (unlikely(!vq->vring.used)) {
return;
}
idx = (idx + vq->used_idx) % vq->vring.num;
uelem.id = elem->index;
uelem.len = len;
vring_used_write(vq, &uelem, idx);
}
static void virtqueue_packed_fill(VirtQueue *vq, const VirtQueueElement *elem,
unsigned int len, unsigned int idx)
{
vq->used_elems[idx].index = elem->index;
vq->used_elems[idx].len = len;
vq->used_elems[idx].ndescs = elem->ndescs;
}
static void virtqueue_packed_fill_desc(VirtQueue *vq,
const VirtQueueElement *elem,
unsigned int idx,
bool strict_order)
{
uint16_t head;
VRingMemoryRegionCaches *caches;
VRingPackedDesc desc = {
.id = elem->index,
.len = elem->len,
};
bool wrap_counter = vq->used_wrap_counter;
if (unlikely(!vq->vring.desc)) {
return;
}
head = vq->used_idx + idx;
if (head >= vq->vring.num) {
head -= vq->vring.num;
wrap_counter ^= 1;
}
if (wrap_counter) {
desc.flags |= (1 << VRING_PACKED_DESC_F_AVAIL);
desc.flags |= (1 << VRING_PACKED_DESC_F_USED);
} else {
desc.flags &= ~(1 << VRING_PACKED_DESC_F_AVAIL);
desc.flags &= ~(1 << VRING_PACKED_DESC_F_USED);
}
caches = vring_get_region_caches(vq);
if (!caches) {
return;
}
vring_packed_desc_write(vq->vdev, &desc, &caches->desc, head, strict_order);
}
/* Called within rcu_read_lock(). */
void virtqueue_fill(VirtQueue *vq, const VirtQueueElement *elem,
unsigned int len, unsigned int idx)
{
trace_virtqueue_fill(vq, elem, len, idx);
virtqueue_unmap_sg(vq, elem, len);
if (virtio_device_disabled(vq->vdev)) {
return;
}
if (virtio_vdev_has_feature(vq->vdev, VIRTIO_F_RING_PACKED)) {
virtqueue_packed_fill(vq, elem, len, idx);
} else {
virtqueue_split_fill(vq, elem, len, idx);
}
}
/* Called within rcu_read_lock(). */
static void virtqueue_split_flush(VirtQueue *vq, unsigned int count)
{
uint16_t old, new;
if (unlikely(!vq->vring.used)) {
return;
}
/* Make sure buffer is written before we update index. */
smp_wmb();
trace_virtqueue_flush(vq, count);
old = vq->used_idx;
new = old + count;
vring_used_idx_set(vq, new);
vq->inuse -= count;
if (unlikely((int16_t)(new - vq->signalled_used) < (uint16_t)(new - old)))
vq->signalled_used_valid = false;
}
static void virtqueue_packed_flush(VirtQueue *vq, unsigned int count)
{
unsigned int i, ndescs = 0;
if (unlikely(!vq->vring.desc)) {
return;
}
for (i = 1; i < count; i++) {
virtqueue_packed_fill_desc(vq, &vq->used_elems[i], i, false);
ndescs += vq->used_elems[i].ndescs;
}
virtqueue_packed_fill_desc(vq, &vq->used_elems[0], 0, true);
ndescs += vq->used_elems[0].ndescs;
vq->inuse -= ndescs;
vq->used_idx += ndescs;
if (vq->used_idx >= vq->vring.num) {
vq->used_idx -= vq->vring.num;
vq->used_wrap_counter ^= 1;
vq->signalled_used_valid = false;
}
}
void virtqueue_flush(VirtQueue *vq, unsigned int count)
{
if (virtio_device_disabled(vq->vdev)) {
vq->inuse -= count;
return;
}
if (virtio_vdev_has_feature(vq->vdev, VIRTIO_F_RING_PACKED)) {
virtqueue_packed_flush(vq, count);
} else {
virtqueue_split_flush(vq, count);
}
}
void virtqueue_push(VirtQueue *vq, const VirtQueueElement *elem,
unsigned int len)
{
RCU_READ_LOCK_GUARD();
virtqueue_fill(vq, elem, len, 0);
virtqueue_flush(vq, 1);
}
/* Called within rcu_read_lock(). */
static int virtqueue_num_heads(VirtQueue *vq, unsigned int idx)
{
uint16_t num_heads = vring_avail_idx(vq) - idx;
/* Check it isn't doing very strange things with descriptor numbers. */
if (num_heads > vq->vring.num) {
virtio_error(vq->vdev, "Guest moved used index from %u to %u",
idx, vq->shadow_avail_idx);
return -EINVAL;
}
/* On success, callers read a descriptor at vq->last_avail_idx.
* Make sure descriptor read does not bypass avail index read. */
if (num_heads) {
smp_rmb();
}
return num_heads;
}
/* Called within rcu_read_lock(). */
static bool virtqueue_get_head(VirtQueue *vq, unsigned int idx,
unsigned int *head)
{
/* Grab the next descriptor number they're advertising, and increment
* the index we've seen. */
*head = vring_avail_ring(vq, idx % vq->vring.num);
/* If their number is silly, that's a fatal mistake. */
if (*head >= vq->vring.num) {
virtio_error(vq->vdev, "Guest says index %u is available", *head);
return false;
}
return true;
}
enum {
VIRTQUEUE_READ_DESC_ERROR = -1,
VIRTQUEUE_READ_DESC_DONE = 0, /* end of chain */
VIRTQUEUE_READ_DESC_MORE = 1, /* more buffers in chain */
};
static int virtqueue_split_read_next_desc(VirtIODevice *vdev, VRingDesc *desc,
MemoryRegionCache *desc_cache,
unsigned int max, unsigned int *next)
{
/* If this descriptor says it doesn't chain, we're done. */
if (!(desc->flags & VRING_DESC_F_NEXT)) {
return VIRTQUEUE_READ_DESC_DONE;
}
/* Check they're not leading us off end of descriptors. */
*next = desc->next;
/* Make sure compiler knows to grab that: we don't want it changing! */
smp_wmb();
if (*next >= max) {
virtio_error(vdev, "Desc next is %u", *next);
return VIRTQUEUE_READ_DESC_ERROR;
}
vring_split_desc_read(vdev, desc, desc_cache, *next);
return VIRTQUEUE_READ_DESC_MORE;
}
/* Called within rcu_read_lock(). */
static void virtqueue_split_get_avail_bytes(VirtQueue *vq,
unsigned int *in_bytes, unsigned int *out_bytes,
unsigned max_in_bytes, unsigned max_out_bytes,
VRingMemoryRegionCaches *caches)
{
VirtIODevice *vdev = vq->vdev;
unsigned int max, idx;
unsigned int total_bufs, in_total, out_total;
MemoryRegionCache indirect_desc_cache = MEMORY_REGION_CACHE_INVALID;
int64_t len = 0;
int rc;
idx = vq->last_avail_idx;
total_bufs = in_total = out_total = 0;
max = vq->vring.num;
while ((rc = virtqueue_num_heads(vq, idx)) > 0) {
MemoryRegionCache *desc_cache = &caches->desc;
unsigned int num_bufs;
VRingDesc desc;
unsigned int i;
num_bufs = total_bufs;
if (!virtqueue_get_head(vq, idx++, &i)) {
goto err;
}
vring_split_desc_read(vdev, &desc, desc_cache, i);
if (desc.flags & VRING_DESC_F_INDIRECT) {
if (!desc.len || (desc.len % sizeof(VRingDesc))) {
virtio_error(vdev, "Invalid size for indirect buffer table");
goto err;
}
/* If we've got too many, that implies a descriptor loop. */
if (num_bufs >= max) {
virtio_error(vdev, "Looped descriptor");
goto err;
}
/* loop over the indirect descriptor table */
len = address_space_cache_init(&indirect_desc_cache,
vdev->dma_as,
desc.addr, desc.len, false);
desc_cache = &indirect_desc_cache;
if (len < desc.len) {
virtio_error(vdev, "Cannot map indirect buffer");
goto err;
}
max = desc.len / sizeof(VRingDesc);
num_bufs = i = 0;
vring_split_desc_read(vdev, &desc, desc_cache, i);
}
do {
/* If we've got too many, that implies a descriptor loop. */
if (++num_bufs > max) {
virtio_error(vdev, "Looped descriptor");
goto err;
}
if (desc.flags & VRING_DESC_F_WRITE) {
in_total += desc.len;
} else {
out_total += desc.len;
}
if (in_total >= max_in_bytes && out_total >= max_out_bytes) {
goto done;
}
rc = virtqueue_split_read_next_desc(vdev, &desc, desc_cache, max, &i);
} while (rc == VIRTQUEUE_READ_DESC_MORE);
if (rc == VIRTQUEUE_READ_DESC_ERROR) {
goto err;
}
if (desc_cache == &indirect_desc_cache) {
address_space_cache_destroy(&indirect_desc_cache);
total_bufs++;
} else {
total_bufs = num_bufs;
}
}
if (rc < 0) {
goto err;
}
done:
address_space_cache_destroy(&indirect_desc_cache);
if (in_bytes) {
*in_bytes = in_total;
}
if (out_bytes) {
*out_bytes = out_total;
}
return;
err:
in_total = out_total = 0;
goto done;
}
static int virtqueue_packed_read_next_desc(VirtQueue *vq,
VRingPackedDesc *desc,
MemoryRegionCache
*desc_cache,
unsigned int max,
unsigned int *next,
bool indirect)
{
/* If this descriptor says it doesn't chain, we're done. */
if (!indirect && !(desc->flags & VRING_DESC_F_NEXT)) {
return VIRTQUEUE_READ_DESC_DONE;
}
++*next;
if (*next == max) {
if (indirect) {
return VIRTQUEUE_READ_DESC_DONE;
} else {
(*next) -= vq->vring.num;
}
}
vring_packed_desc_read(vq->vdev, desc, desc_cache, *next, false);
return VIRTQUEUE_READ_DESC_MORE;
}
/* Called within rcu_read_lock(). */
static void virtqueue_packed_get_avail_bytes(VirtQueue *vq,
unsigned int *in_bytes,
unsigned int *out_bytes,
unsigned max_in_bytes,
unsigned max_out_bytes,
VRingMemoryRegionCaches *caches)
{
VirtIODevice *vdev = vq->vdev;
unsigned int max, idx;
unsigned int total_bufs, in_total, out_total;
MemoryRegionCache *desc_cache;
MemoryRegionCache indirect_desc_cache = MEMORY_REGION_CACHE_INVALID;
int64_t len = 0;
VRingPackedDesc desc;
bool wrap_counter;
idx = vq->last_avail_idx;
wrap_counter = vq->last_avail_wrap_counter;
total_bufs = in_total = out_total = 0;
max = vq->vring.num;
for (;;) {
unsigned int num_bufs = total_bufs;
unsigned int i = idx;
int rc;
desc_cache = &caches->desc;
vring_packed_desc_read(vdev, &desc, desc_cache, idx, true);
if (!is_desc_avail(desc.flags, wrap_counter)) {
break;
}
if (desc.flags & VRING_DESC_F_INDIRECT) {
if (desc.len % sizeof(VRingPackedDesc)) {
virtio_error(vdev, "Invalid size for indirect buffer table");
goto err;
}
/* If we've got too many, that implies a descriptor loop. */
if (num_bufs >= max) {
virtio_error(vdev, "Looped descriptor");
goto err;
}
/* loop over the indirect descriptor table */
len = address_space_cache_init(&indirect_desc_cache,
vdev->dma_as,
desc.addr, desc.len, false);
desc_cache = &indirect_desc_cache;
if (len < desc.len) {
virtio_error(vdev, "Cannot map indirect buffer");
goto err;
}
max = desc.len / sizeof(VRingPackedDesc);
num_bufs = i = 0;
vring_packed_desc_read(vdev, &desc, desc_cache, i, false);
}
do {
/* If we've got too many, that implies a descriptor loop. */
if (++num_bufs > max) {
virtio_error(vdev, "Looped descriptor");
goto err;
}
if (desc.flags & VRING_DESC_F_WRITE) {
in_total += desc.len;
} else {
out_total += desc.len;
}
if (in_total >= max_in_bytes && out_total >= max_out_bytes) {
goto done;
}
rc = virtqueue_packed_read_next_desc(vq, &desc, desc_cache, max,
&i, desc_cache ==
&indirect_desc_cache);
} while (rc == VIRTQUEUE_READ_DESC_MORE);
if (desc_cache == &indirect_desc_cache) {
address_space_cache_destroy(&indirect_desc_cache);
total_bufs++;
idx++;
} else {
idx += num_bufs - total_bufs;
total_bufs = num_bufs;
}
if (idx >= vq->vring.num) {
idx -= vq->vring.num;
wrap_counter ^= 1;
}
}
/* Record the index and wrap counter for a kick we want */
vq->shadow_avail_idx = idx;
vq->shadow_avail_wrap_counter = wrap_counter;
done:
address_space_cache_destroy(&indirect_desc_cache);
if (in_bytes) {
*in_bytes = in_total;
}
if (out_bytes) {
*out_bytes = out_total;
}
return;
err:
in_total = out_total = 0;
goto done;
}
void virtqueue_get_avail_bytes(VirtQueue *vq, unsigned int *in_bytes,
unsigned int *out_bytes,
unsigned max_in_bytes, unsigned max_out_bytes)
{
uint16_t desc_size;
VRingMemoryRegionCaches *caches;
RCU_READ_LOCK_GUARD();
if (unlikely(!vq->vring.desc)) {
goto err;
}
caches = vring_get_region_caches(vq);
if (!caches) {
goto err;
}
desc_size = virtio_vdev_has_feature(vq->vdev, VIRTIO_F_RING_PACKED) ?
sizeof(VRingPackedDesc) : sizeof(VRingDesc);
if (caches->desc.len < vq->vring.num * desc_size) {
virtio_error(vq->vdev, "Cannot map descriptor ring");
goto err;
}
if (virtio_vdev_has_feature(vq->vdev, VIRTIO_F_RING_PACKED)) {
virtqueue_packed_get_avail_bytes(vq, in_bytes, out_bytes,
max_in_bytes, max_out_bytes,
caches);
} else {
virtqueue_split_get_avail_bytes(vq, in_bytes, out_bytes,
max_in_bytes, max_out_bytes,
caches);
}
return;
err:
if (in_bytes) {
*in_bytes = 0;
}
if (out_bytes) {
*out_bytes = 0;
}
}
int virtqueue_avail_bytes(VirtQueue *vq, unsigned int in_bytes,
unsigned int out_bytes)
{
unsigned int in_total, out_total;
virtqueue_get_avail_bytes(vq, &in_total, &out_total, in_bytes, out_bytes);
return in_bytes <= in_total && out_bytes <= out_total;
}
static bool virtqueue_map_desc(VirtIODevice *vdev, unsigned int *p_num_sg,
hwaddr *addr, struct iovec *iov,
unsigned int max_num_sg, bool is_write,
hwaddr pa, size_t sz)
{
bool ok = false;
unsigned num_sg = *p_num_sg;
assert(num_sg <= max_num_sg);
if (!sz) {
virtio_error(vdev, "virtio: zero sized buffers are not allowed");
goto out;
}
while (sz) {
hwaddr len = sz;
if (num_sg == max_num_sg) {
virtio_error(vdev, "virtio: too many write descriptors in "
"indirect table");
goto out;
}
iov[num_sg].iov_base = dma_memory_map(vdev->dma_as, pa, &len,
is_write ?
DMA_DIRECTION_FROM_DEVICE :
DMA_DIRECTION_TO_DEVICE,
MEMTXATTRS_UNSPECIFIED);
if (!iov[num_sg].iov_base) {
virtio_error(vdev, "virtio: bogus descriptor or out of resources");
goto out;
}
iov[num_sg].iov_len = len;
addr[num_sg] = pa;
sz -= len;
pa += len;
num_sg++;
}
ok = true;
out:
*p_num_sg = num_sg;
return ok;
}
/* Only used by error code paths before we have a VirtQueueElement (therefore
* virtqueue_unmap_sg() can't be used). Assumes buffers weren't written to
* yet.
*/
static void virtqueue_undo_map_desc(unsigned int out_num, unsigned int in_num,
struct iovec *iov)
{
unsigned int i;
for (i = 0; i < out_num + in_num; i++) {
int is_write = i >= out_num;
cpu_physical_memory_unmap(iov->iov_base, iov->iov_len, is_write, 0);
iov++;
}
}
static void virtqueue_map_iovec(VirtIODevice *vdev, struct iovec *sg,
hwaddr *addr, unsigned int num_sg,
bool is_write)
{
unsigned int i;
hwaddr len;
for (i = 0; i < num_sg; i++) {
len = sg[i].iov_len;
sg[i].iov_base = dma_memory_map(vdev->dma_as,
addr[i], &len, is_write ?
DMA_DIRECTION_FROM_DEVICE :
DMA_DIRECTION_TO_DEVICE,
MEMTXATTRS_UNSPECIFIED);
if (!sg[i].iov_base) {
error_report("virtio: error trying to map MMIO memory");
exit(1);
}
if (len != sg[i].iov_len) {
error_report("virtio: unexpected memory split");
exit(1);
}
}
}
void virtqueue_map(VirtIODevice *vdev, VirtQueueElement *elem)
{
virtqueue_map_iovec(vdev, elem->in_sg, elem->in_addr, elem->in_num, true);
virtqueue_map_iovec(vdev, elem->out_sg, elem->out_addr, elem->out_num,
false);
}
static void *virtqueue_alloc_element(size_t sz, unsigned out_num, unsigned in_num)
{
VirtQueueElement *elem;
size_t in_addr_ofs = QEMU_ALIGN_UP(sz, __alignof__(elem->in_addr[0]));
size_t out_addr_ofs = in_addr_ofs + in_num * sizeof(elem->in_addr[0]);
size_t out_addr_end = out_addr_ofs + out_num * sizeof(elem->out_addr[0]);
size_t in_sg_ofs = QEMU_ALIGN_UP(out_addr_end, __alignof__(elem->in_sg[0]));
size_t out_sg_ofs = in_sg_ofs + in_num * sizeof(elem->in_sg[0]);
size_t out_sg_end = out_sg_ofs + out_num * sizeof(elem->out_sg[0]);
assert(sz >= sizeof(VirtQueueElement));
elem = g_malloc(out_sg_end);
trace_virtqueue_alloc_element(elem, sz, in_num, out_num);
elem->out_num = out_num;
elem->in_num = in_num;
elem->in_addr = (void *)elem + in_addr_ofs;
elem->out_addr = (void *)elem + out_addr_ofs;
elem->in_sg = (void *)elem + in_sg_ofs;
elem->out_sg = (void *)elem + out_sg_ofs;
return elem;
}
static void *virtqueue_split_pop(VirtQueue *vq, size_t sz)
{
unsigned int i, head, max;
VRingMemoryRegionCaches *caches;
MemoryRegionCache indirect_desc_cache = MEMORY_REGION_CACHE_INVALID;
MemoryRegionCache *desc_cache;
int64_t len;
VirtIODevice *vdev = vq->vdev;
VirtQueueElement *elem = NULL;
unsigned out_num, in_num, elem_entries;
hwaddr addr[VIRTQUEUE_MAX_SIZE];
struct iovec iov[VIRTQUEUE_MAX_SIZE];
VRingDesc desc;
int rc;
RCU_READ_LOCK_GUARD();
if (virtio_queue_empty_rcu(vq)) {
goto done;
}
/* Needed after virtio_queue_empty(), see comment in
* virtqueue_num_heads(). */
smp_rmb();
/* When we start there are none of either input nor output. */
out_num = in_num = elem_entries = 0;
max = vq->vring.num;
if (vq->inuse >= vq->vring.num) {
virtio_error(vdev, "Virtqueue size exceeded");
goto done;
}
if (!virtqueue_get_head(vq, vq->last_avail_idx++, &head)) {
goto done;
}
if (virtio_vdev_has_feature(vdev, VIRTIO_RING_F_EVENT_IDX)) {
vring_set_avail_event(vq, vq->last_avail_idx);
}
i = head;
caches = vring_get_region_caches(vq);
if (!caches) {
virtio_error(vdev, "Region caches not initialized");
goto done;
}
if (caches->desc.len < max * sizeof(VRingDesc)) {
virtio_error(vdev, "Cannot map descriptor ring");
goto done;
}
desc_cache = &caches->desc;
vring_split_desc_read(vdev, &desc, desc_cache, i);
if (desc.flags & VRING_DESC_F_INDIRECT) {
if (!desc.len || (desc.len % sizeof(VRingDesc))) {
virtio_error(vdev, "Invalid size for indirect buffer table");
goto done;
}
/* loop over the indirect descriptor table */
len = address_space_cache_init(&indirect_desc_cache, vdev->dma_as,
desc.addr, desc.len, false);
desc_cache = &indirect_desc_cache;
if (len < desc.len) {
virtio_error(vdev, "Cannot map indirect buffer");
goto done;
}
max = desc.len / sizeof(VRingDesc);
i = 0;
vring_split_desc_read(vdev, &desc, desc_cache, i);
}
/* Collect all the descriptors */
do {
bool map_ok;
if (desc.flags & VRING_DESC_F_WRITE) {
map_ok = virtqueue_map_desc(vdev, &in_num, addr + out_num,
iov + out_num,
VIRTQUEUE_MAX_SIZE - out_num, true,
desc.addr, desc.len);
} else {
if (in_num) {
virtio_error(vdev, "Incorrect order for descriptors");
goto err_undo_map;
}
map_ok = virtqueue_map_desc(vdev, &out_num, addr, iov,
VIRTQUEUE_MAX_SIZE, false,
desc.addr, desc.len);
}
if (!map_ok) {
goto err_undo_map;
}
/* If we've got too many, that implies a descriptor loop. */
if (++elem_entries > max) {
virtio_error(vdev, "Looped descriptor");
goto err_undo_map;
}
rc = virtqueue_split_read_next_desc(vdev, &desc, desc_cache, max, &i);
} while (rc == VIRTQUEUE_READ_DESC_MORE);
if (rc == VIRTQUEUE_READ_DESC_ERROR) {
goto err_undo_map;
}
/* Now copy what we have collected and mapped */
elem = virtqueue_alloc_element(sz, out_num, in_num);
elem->index = head;
elem->ndescs = 1;
for (i = 0; i < out_num; i++) {
elem->out_addr[i] = addr[i];
elem->out_sg[i] = iov[i];
}
for (i = 0; i < in_num; i++) {
elem->in_addr[i] = addr[out_num + i];
elem->in_sg[i] = iov[out_num + i];
}
vq->inuse++;
trace_virtqueue_pop(vq, elem, elem->in_num, elem->out_num);
done:
address_space_cache_destroy(&indirect_desc_cache);
return elem;
err_undo_map:
virtqueue_undo_map_desc(out_num, in_num, iov);
goto done;
}
static void *virtqueue_packed_pop(VirtQueue *vq, size_t sz)
{
unsigned int i, max;
VRingMemoryRegionCaches *caches;
MemoryRegionCache indirect_desc_cache = MEMORY_REGION_CACHE_INVALID;
MemoryRegionCache *desc_cache;
int64_t len;
VirtIODevice *vdev = vq->vdev;
VirtQueueElement *elem = NULL;
unsigned out_num, in_num, elem_entries;
hwaddr addr[VIRTQUEUE_MAX_SIZE];
struct iovec iov[VIRTQUEUE_MAX_SIZE];
VRingPackedDesc desc;
uint16_t id;
int rc;
RCU_READ_LOCK_GUARD();
if (virtio_queue_packed_empty_rcu(vq)) {
goto done;
}
/* When we start there are none of either input nor output. */
out_num = in_num = elem_entries = 0;
max = vq->vring.num;
if (vq->inuse >= vq->vring.num) {
virtio_error(vdev, "Virtqueue size exceeded");
goto done;
}
i = vq->last_avail_idx;
caches = vring_get_region_caches(vq);
if (!caches) {
virtio_error(vdev, "Region caches not initialized");
goto done;
}
if (caches->desc.len < max * sizeof(VRingDesc)) {
virtio_error(vdev, "Cannot map descriptor ring");
goto done;
}
desc_cache = &caches->desc;
vring_packed_desc_read(vdev, &desc, desc_cache, i, true);
id = desc.id;
if (desc.flags & VRING_DESC_F_INDIRECT) {
if (desc.len % sizeof(VRingPackedDesc)) {
virtio_error(vdev, "Invalid size for indirect buffer table");
goto done;
}
/* loop over the indirect descriptor table */
len = address_space_cache_init(&indirect_desc_cache, vdev->dma_as,
desc.addr, desc.len, false);
desc_cache = &indirect_desc_cache;
if (len < desc.len) {
virtio_error(vdev, "Cannot map indirect buffer");
goto done;
}
max = desc.len / sizeof(VRingPackedDesc);
i = 0;
vring_packed_desc_read(vdev, &desc, desc_cache, i, false);
}
/* Collect all the descriptors */
do {
bool map_ok;
if (desc.flags & VRING_DESC_F_WRITE) {
map_ok = virtqueue_map_desc(vdev, &in_num, addr + out_num,
iov + out_num,
VIRTQUEUE_MAX_SIZE - out_num, true,
desc.addr, desc.len);
} else {
if (in_num) {
virtio_error(vdev, "Incorrect order for descriptors");
goto err_undo_map;
}
map_ok = virtqueue_map_desc(vdev, &out_num, addr, iov,
VIRTQUEUE_MAX_SIZE, false,
desc.addr, desc.len);
}
if (!map_ok) {
goto err_undo_map;
}
/* If we've got too many, that implies a descriptor loop. */
if (++elem_entries > max) {
virtio_error(vdev, "Looped descriptor");
goto err_undo_map;
}
rc = virtqueue_packed_read_next_desc(vq, &desc, desc_cache, max, &i,
desc_cache ==
&indirect_desc_cache);
} while (rc == VIRTQUEUE_READ_DESC_MORE);
/* Now copy what we have collected and mapped */
elem = virtqueue_alloc_element(sz, out_num, in_num);
for (i = 0; i < out_num; i++) {
elem->out_addr[i] = addr[i];
elem->out_sg[i] = iov[i];
}
for (i = 0; i < in_num; i++) {
elem->in_addr[i] = addr[out_num + i];
elem->in_sg[i] = iov[out_num + i];
}
elem->index = id;
elem->ndescs = (desc_cache == &indirect_desc_cache) ? 1 : elem_entries;
vq->last_avail_idx += elem->ndescs;
vq->inuse += elem->ndescs;
if (vq->last_avail_idx >= vq->vring.num) {
vq->last_avail_idx -= vq->vring.num;
vq->last_avail_wrap_counter ^= 1;
}
vq->shadow_avail_idx = vq->last_avail_idx;
vq->shadow_avail_wrap_counter = vq->last_avail_wrap_counter;
trace_virtqueue_pop(vq, elem, elem->in_num, elem->out_num);
done:
address_space_cache_destroy(&indirect_desc_cache);
return elem;
err_undo_map:
virtqueue_undo_map_desc(out_num, in_num, iov);
goto done;
}
void *virtqueue_pop(VirtQueue *vq, size_t sz)
{
if (virtio_device_disabled(vq->vdev)) {
return NULL;
}
if (virtio_vdev_has_feature(vq->vdev, VIRTIO_F_RING_PACKED)) {
return virtqueue_packed_pop(vq, sz);
} else {
return virtqueue_split_pop(vq, sz);
}
}
static unsigned int virtqueue_packed_drop_all(VirtQueue *vq)
{
VRingMemoryRegionCaches *caches;
MemoryRegionCache *desc_cache;
unsigned int dropped = 0;
VirtQueueElement elem = {};
VirtIODevice *vdev = vq->vdev;
VRingPackedDesc desc;
RCU_READ_LOCK_GUARD();
caches = vring_get_region_caches(vq);
if (!caches) {
return 0;
}
desc_cache = &caches->desc;
virtio_queue_set_notification(vq, 0);
while (vq->inuse < vq->vring.num) {
unsigned int idx = vq->last_avail_idx;
/*
* works similar to virtqueue_pop but does not map buffers
* and does not allocate any memory.
*/
vring_packed_desc_read(vdev, &desc, desc_cache,
vq->last_avail_idx , true);
if (!is_desc_avail(desc.flags, vq->last_avail_wrap_counter)) {
break;
}
elem.index = desc.id;
elem.ndescs = 1;
while (virtqueue_packed_read_next_desc(vq, &desc, desc_cache,
vq->vring.num, &idx, false)) {
++elem.ndescs;
}
/*
* immediately push the element, nothing to unmap
* as both in_num and out_num are set to 0.
*/
virtqueue_push(vq, &elem, 0);
dropped++;
vq->last_avail_idx += elem.ndescs;
if (vq->last_avail_idx >= vq->vring.num) {
vq->last_avail_idx -= vq->vring.num;
vq->last_avail_wrap_counter ^= 1;
}
}
return dropped;
}
static unsigned int virtqueue_split_drop_all(VirtQueue *vq)
{
unsigned int dropped = 0;
VirtQueueElement elem = {};
VirtIODevice *vdev = vq->vdev;
bool fEventIdx = virtio_vdev_has_feature(vdev, VIRTIO_RING_F_EVENT_IDX);
while (!virtio_queue_empty(vq) && vq->inuse < vq->vring.num) {
/* works similar to virtqueue_pop but does not map buffers
* and does not allocate any memory */
smp_rmb();
if (!virtqueue_get_head(vq, vq->last_avail_idx, &elem.index)) {
break;
}
vq->inuse++;
vq->last_avail_idx++;
if (fEventIdx) {
vring_set_avail_event(vq, vq->last_avail_idx);
}
/* immediately push the element, nothing to unmap
* as both in_num and out_num are set to 0 */
virtqueue_push(vq, &elem, 0);
dropped++;
}
return dropped;
}
/* virtqueue_drop_all:
* @vq: The #VirtQueue
* Drops all queued buffers and indicates them to the guest
* as if they are done. Useful when buffers can not be
* processed but must be returned to the guest.
*/
unsigned int virtqueue_drop_all(VirtQueue *vq)
{
struct VirtIODevice *vdev = vq->vdev;
if (virtio_device_disabled(vq->vdev)) {
return 0;
}
if (virtio_vdev_has_feature(vdev, VIRTIO_F_RING_PACKED)) {
return virtqueue_packed_drop_all(vq);
} else {
return virtqueue_split_drop_all(vq);
}
}
/* Reading and writing a structure directly to QEMUFile is *awful*, but
* it is what QEMU has always done by mistake. We can change it sooner
* or later by bumping the version number of the affected vm states.
* In the meanwhile, since the in-memory layout of VirtQueueElement
* has changed, we need to marshal to and from the layout that was
* used before the change.
*/
typedef struct VirtQueueElementOld {
unsigned int index;
unsigned int out_num;
unsigned int in_num;
hwaddr in_addr[VIRTQUEUE_MAX_SIZE];
hwaddr out_addr[VIRTQUEUE_MAX_SIZE];
struct iovec in_sg[VIRTQUEUE_MAX_SIZE];
struct iovec out_sg[VIRTQUEUE_MAX_SIZE];
} VirtQueueElementOld;
void *qemu_get_virtqueue_element(VirtIODevice *vdev, QEMUFile *f, size_t sz)
{
VirtQueueElement *elem;
VirtQueueElementOld data;
int i;
qemu_get_buffer(f, (uint8_t *)&data, sizeof(VirtQueueElementOld));
/* TODO: teach all callers that this can fail, and return failure instead
* of asserting here.
* This is just one thing (there are probably more) that must be
* fixed before we can allow NDEBUG compilation.
*/
assert(ARRAY_SIZE(data.in_addr) >= data.in_num);
assert(ARRAY_SIZE(data.out_addr) >= data.out_num);
elem = virtqueue_alloc_element(sz, data.out_num, data.in_num);
elem->index = data.index;
for (i = 0; i < elem->in_num; i++) {
elem->in_addr[i] = data.in_addr[i];
}
for (i = 0; i < elem->out_num; i++) {
elem->out_addr[i] = data.out_addr[i];
}
for (i = 0; i < elem->in_num; i++) {
/* Base is overwritten by virtqueue_map. */
elem->in_sg[i].iov_base = 0;
elem->in_sg[i].iov_len = data.in_sg[i].iov_len;
}
for (i = 0; i < elem->out_num; i++) {
/* Base is overwritten by virtqueue_map. */
elem->out_sg[i].iov_base = 0;
elem->out_sg[i].iov_len = data.out_sg[i].iov_len;
}
if (virtio_host_has_feature(vdev, VIRTIO_F_RING_PACKED)) {
qemu_get_be32s(f, &elem->ndescs);
}
virtqueue_map(vdev, elem);
return elem;
}
void qemu_put_virtqueue_element(VirtIODevice *vdev, QEMUFile *f,
VirtQueueElement *elem)
{
VirtQueueElementOld data;
int i;
memset(&data, 0, sizeof(data));
data.index = elem->index;
data.in_num = elem->in_num;
data.out_num = elem->out_num;
for (i = 0; i < elem->in_num; i++) {
data.in_addr[i] = elem->in_addr[i];
}
for (i = 0; i < elem->out_num; i++) {
data.out_addr[i] = elem->out_addr[i];
}
for (i = 0; i < elem->in_num; i++) {
/* Base is overwritten by virtqueue_map when loading. Do not
* save it, as it would leak the QEMU address space layout. */
data.in_sg[i].iov_len = elem->in_sg[i].iov_len;
}
for (i = 0; i < elem->out_num; i++) {
/* Do not save iov_base as above. */
data.out_sg[i].iov_len = elem->out_sg[i].iov_len;
}
if (virtio_host_has_feature(vdev, VIRTIO_F_RING_PACKED)) {
qemu_put_be32s(f, &elem->ndescs);
}
qemu_put_buffer(f, (uint8_t *)&data, sizeof(VirtQueueElementOld));
}
/* virtio device */
static void virtio_notify_vector(VirtIODevice *vdev, uint16_t vector)
{
BusState *qbus = qdev_get_parent_bus(DEVICE(vdev));
VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
if (virtio_device_disabled(vdev)) {
return;
}
if (k->notify) {
k->notify(qbus->parent, vector);
}
}
void virtio_update_irq(VirtIODevice *vdev)
{
virtio_notify_vector(vdev, VIRTIO_NO_VECTOR);
}
static int virtio_validate_features(VirtIODevice *vdev)
{
VirtioDeviceClass *k = VIRTIO_DEVICE_GET_CLASS(vdev);
if (virtio_host_has_feature(vdev, VIRTIO_F_IOMMU_PLATFORM) &&
!virtio_vdev_has_feature(vdev, VIRTIO_F_IOMMU_PLATFORM)) {
return -EFAULT;
}
if (k->validate_features) {
return k->validate_features(vdev);
} else {
return 0;
}
}
int virtio_set_status(VirtIODevice *vdev, uint8_t val)
{
VirtioDeviceClass *k = VIRTIO_DEVICE_GET_CLASS(vdev);
trace_virtio_set_status(vdev, val);
if (virtio_vdev_has_feature(vdev, VIRTIO_F_VERSION_1)) {
if (!(vdev->status & VIRTIO_CONFIG_S_FEATURES_OK) &&
val & VIRTIO_CONFIG_S_FEATURES_OK) {
int ret = virtio_validate_features(vdev);
if (ret) {
return ret;
}
}
}
if ((vdev->status & VIRTIO_CONFIG_S_DRIVER_OK) !=
(val & VIRTIO_CONFIG_S_DRIVER_OK)) {
virtio_set_started(vdev, val & VIRTIO_CONFIG_S_DRIVER_OK);
}
if (k->set_status) {
k->set_status(vdev, val);
}
vdev->status = val;
return 0;
}
static enum virtio_device_endian virtio_default_endian(void)
{
if (target_words_bigendian()) {
return VIRTIO_DEVICE_ENDIAN_BIG;
} else {
return VIRTIO_DEVICE_ENDIAN_LITTLE;
}
}
static enum virtio_device_endian virtio_current_cpu_endian(void)
{
if (cpu_virtio_is_big_endian(current_cpu)) {
return VIRTIO_DEVICE_ENDIAN_BIG;
} else {
return VIRTIO_DEVICE_ENDIAN_LITTLE;
}
}
void virtio_reset(void *opaque)
{
VirtIODevice *vdev = opaque;
VirtioDeviceClass *k = VIRTIO_DEVICE_GET_CLASS(vdev);
int i;
virtio_set_status(vdev, 0);
if (current_cpu) {
/* Guest initiated reset */
vdev->device_endian = virtio_current_cpu_endian();
} else {
/* System reset */
vdev->device_endian = virtio_default_endian();
}
if (k->reset) {
k->reset(vdev);
}
vdev->start_on_kick = false;
vdev->started = false;
vdev->broken = false;
vdev->guest_features = 0;
vdev->queue_sel = 0;
vdev->status = 0;
vdev->disabled = false;
qatomic_set(&vdev->isr, 0);
vdev->config_vector = VIRTIO_NO_VECTOR;
virtio_notify_vector(vdev, vdev->config_vector);
for(i = 0; i < VIRTIO_QUEUE_MAX; i++) {
vdev->vq[i].vring.desc = 0;
vdev->vq[i].vring.avail = 0;
vdev->vq[i].vring.used = 0;
vdev->vq[i].last_avail_idx = 0;
vdev->vq[i].shadow_avail_idx = 0;
vdev->vq[i].used_idx = 0;
vdev->vq[i].last_avail_wrap_counter = true;
vdev->vq[i].shadow_avail_wrap_counter = true;
vdev->vq[i].used_wrap_counter = true;
virtio_queue_set_vector(vdev, i, VIRTIO_NO_VECTOR);
vdev->vq[i].signalled_used = 0;
vdev->vq[i].signalled_used_valid = false;
vdev->vq[i].notification = true;
vdev->vq[i].vring.num = vdev->vq[i].vring.num_default;
vdev->vq[i].inuse = 0;
virtio_virtqueue_reset_region_cache(&vdev->vq[i]);
}
}
uint32_t virtio_config_readb(VirtIODevice *vdev, uint32_t addr)
{
VirtioDeviceClass *k = VIRTIO_DEVICE_GET_CLASS(vdev);
uint8_t val;
if (addr + sizeof(val) > vdev->config_len) {
return (uint32_t)-1;
}
k->get_config(vdev, vdev->config);
val = ldub_p(vdev->config + addr);
return val;
}
uint32_t virtio_config_readw(VirtIODevice *vdev, uint32_t addr)
{
VirtioDeviceClass *k = VIRTIO_DEVICE_GET_CLASS(vdev);
uint16_t val;
if (addr + sizeof(val) > vdev->config_len) {
return (uint32_t)-1;
}
k->get_config(vdev, vdev->config);
val = lduw_p(vdev->config + addr);
return val;
}
uint32_t virtio_config_readl(VirtIODevice *vdev, uint32_t addr)
{
VirtioDeviceClass *k = VIRTIO_DEVICE_GET_CLASS(vdev);
uint32_t val;
if (addr + sizeof(val) > vdev->config_len) {
return (uint32_t)-1;
}
k->get_config(vdev, vdev->config);
val = ldl_p(vdev->config + addr);
return val;
}
void virtio_config_writeb(VirtIODevice *vdev, uint32_t addr, uint32_t data)
{
VirtioDeviceClass *k = VIRTIO_DEVICE_GET_CLASS(vdev);
uint8_t val = data;
if (addr + sizeof(val) > vdev->config_len) {
return;
}
stb_p(vdev->config + addr, val);
if (k->set_config) {
k->set_config(vdev, vdev->config);
}
}
void virtio_config_writew(VirtIODevice *vdev, uint32_t addr, uint32_t data)
{
VirtioDeviceClass *k = VIRTIO_DEVICE_GET_CLASS(vdev);
uint16_t val = data;
if (addr + sizeof(val) > vdev->config_len) {
return;
}
stw_p(vdev->config + addr, val);
if (k->set_config) {
k->set_config(vdev, vdev->config);
}
}
void virtio_config_writel(VirtIODevice *vdev, uint32_t addr, uint32_t data)
{
VirtioDeviceClass *k = VIRTIO_DEVICE_GET_CLASS(vdev);
uint32_t val = data;
if (addr + sizeof(val) > vdev->config_len) {
return;
}
stl_p(vdev->config + addr, val);
if (k->set_config) {
k->set_config(vdev, vdev->config);
}
}
uint32_t virtio_config_modern_readb(VirtIODevice *vdev, uint32_t addr)
{
VirtioDeviceClass *k = VIRTIO_DEVICE_GET_CLASS(vdev);
uint8_t val;
if (addr + sizeof(val) > vdev->config_len) {
return (uint32_t)-1;
}
k->get_config(vdev, vdev->config);
val = ldub_p(vdev->config + addr);
return val;
}
uint32_t virtio_config_modern_readw(VirtIODevice *vdev, uint32_t addr)
{
VirtioDeviceClass *k = VIRTIO_DEVICE_GET_CLASS(vdev);
uint16_t val;
if (addr + sizeof(val) > vdev->config_len) {
return (uint32_t)-1;
}
k->get_config(vdev, vdev->config);
val = lduw_le_p(vdev->config + addr);
return val;
}
uint32_t virtio_config_modern_readl(VirtIODevice *vdev, uint32_t addr)
{
VirtioDeviceClass *k = VIRTIO_DEVICE_GET_CLASS(vdev);
uint32_t val;
if (addr + sizeof(val) > vdev->config_len) {
return (uint32_t)-1;
}
k->get_config(vdev, vdev->config);
val = ldl_le_p(vdev->config + addr);
return val;
}
void virtio_config_modern_writeb(VirtIODevice *vdev,
uint32_t addr, uint32_t data)
{
VirtioDeviceClass *k = VIRTIO_DEVICE_GET_CLASS(vdev);
uint8_t val = data;
if (addr + sizeof(val) > vdev->config_len) {
return;
}
stb_p(vdev->config + addr, val);
if (k->set_config) {
k->set_config(vdev, vdev->config);
}
}
void virtio_config_modern_writew(VirtIODevice *vdev,
uint32_t addr, uint32_t data)
{
VirtioDeviceClass *k = VIRTIO_DEVICE_GET_CLASS(vdev);
uint16_t val = data;
if (addr + sizeof(val) > vdev->config_len) {
return;
}
stw_le_p(vdev->config + addr, val);
if (k->set_config) {
k->set_config(vdev, vdev->config);
}
}
void virtio_config_modern_writel(VirtIODevice *vdev,
uint32_t addr, uint32_t data)
{
VirtioDeviceClass *k = VIRTIO_DEVICE_GET_CLASS(vdev);
uint32_t val = data;
if (addr + sizeof(val) > vdev->config_len) {
return;
}
stl_le_p(vdev->config + addr, val);
if (k->set_config) {
k->set_config(vdev, vdev->config);
}
}
void virtio_queue_set_addr(VirtIODevice *vdev, int n, hwaddr addr)
{
if (!vdev->vq[n].vring.num) {
return;
}
vdev->vq[n].vring.desc = addr;
virtio_queue_update_rings(vdev, n);
}
hwaddr virtio_queue_get_addr(VirtIODevice *vdev, int n)
{
return vdev->vq[n].vring.desc;
}
void virtio_queue_set_rings(VirtIODevice *vdev, int n, hwaddr desc,
hwaddr avail, hwaddr used)
{
if (!vdev->vq[n].vring.num) {
return;
}
vdev->vq[n].vring.desc = desc;
vdev->vq[n].vring.avail = avail;
vdev->vq[n].vring.used = used;
virtio_init_region_cache(vdev, n);
}
void virtio_queue_set_num(VirtIODevice *vdev, int n, int num)
{
/* Don't allow guest to flip queue between existent and
* nonexistent states, or to set it to an invalid size.
*/
if (!!num != !!vdev->vq[n].vring.num ||
num > VIRTQUEUE_MAX_SIZE ||
num < 0) {
return;
}
vdev->vq[n].vring.num = num;
}
VirtQueue *virtio_vector_first_queue(VirtIODevice *vdev, uint16_t vector)
{
return QLIST_FIRST(&vdev->vector_queues[vector]);
}
VirtQueue *virtio_vector_next_queue(VirtQueue *vq)
{
return QLIST_NEXT(vq, node);
}
int virtio_queue_get_num(VirtIODevice *vdev, int n)
{
return vdev->vq[n].vring.num;
}
int virtio_queue_get_max_num(VirtIODevice *vdev, int n)
{
return vdev->vq[n].vring.num_default;
}
int virtio_get_num_queues(VirtIODevice *vdev)
{
int i;
for (i = 0; i < VIRTIO_QUEUE_MAX; i++) {
if (!virtio_queue_get_num(vdev, i)) {
break;
}
}
return i;
}
void virtio_queue_set_align(VirtIODevice *vdev, int n, int align)
{
BusState *qbus = qdev_get_parent_bus(DEVICE(vdev));
VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
/* virtio-1 compliant devices cannot change the alignment */
if (virtio_vdev_has_feature(vdev, VIRTIO_F_VERSION_1)) {
error_report("tried to modify queue alignment for virtio-1 device");
return;
}
/* Check that the transport told us it was going to do this
* (so a buggy transport will immediately assert rather than
* silently failing to migrate this state)
*/
assert(k->has_variable_vring_alignment);
if (align) {
vdev->vq[n].vring.align = align;
virtio_queue_update_rings(vdev, n);
}
}
static void virtio_queue_notify_vq(VirtQueue *vq)
{
if (vq->vring.desc && vq->handle_output) {
VirtIODevice *vdev = vq->vdev;
if (unlikely(vdev->broken)) {
return;
}
trace_virtio_queue_notify(vdev, vq - vdev->vq, vq);
vq->handle_output(vdev, vq);
if (unlikely(vdev->start_on_kick)) {
virtio_set_started(vdev, true);
}
}
}
void virtio_queue_notify(VirtIODevice *vdev, int n)
{
VirtQueue *vq = &vdev->vq[n];
if (unlikely(!vq->vring.desc || vdev->broken)) {
return;
}
trace_virtio_queue_notify(vdev, vq - vdev->vq, vq);
if (vq->host_notifier_enabled) {
event_notifier_set(&vq->host_notifier);
} else if (vq->handle_output) {
vq->handle_output(vdev, vq);
if (unlikely(vdev->start_on_kick)) {
virtio_set_started(vdev, true);
}
}
}
uint16_t virtio_queue_vector(VirtIODevice *vdev, int n)
{
return n < VIRTIO_QUEUE_MAX ? vdev->vq[n].vector :
VIRTIO_NO_VECTOR;
}
void virtio_queue_set_vector(VirtIODevice *vdev, int n, uint16_t vector)
{
VirtQueue *vq = &vdev->vq[n];
if (n < VIRTIO_QUEUE_MAX) {
if (vdev->vector_queues &&
vdev->vq[n].vector != VIRTIO_NO_VECTOR) {
QLIST_REMOVE(vq, node);
}
vdev->vq[n].vector = vector;
if (vdev->vector_queues &&
vector != VIRTIO_NO_VECTOR) {
QLIST_INSERT_HEAD(&vdev->vector_queues[vector], vq, node);
}
}
}
VirtQueue *virtio_add_queue(VirtIODevice *vdev, int queue_size,
VirtIOHandleOutput handle_output)
{
int i;
for (i = 0; i < VIRTIO_QUEUE_MAX; i++) {
if (vdev->vq[i].vring.num == 0)
break;
}
if (i == VIRTIO_QUEUE_MAX || queue_size > VIRTQUEUE_MAX_SIZE)
abort();
vdev->vq[i].vring.num = queue_size;
vdev->vq[i].vring.num_default = queue_size;
vdev->vq[i].vring.align = VIRTIO_PCI_VRING_ALIGN;
vdev->vq[i].handle_output = handle_output;
vdev->vq[i].used_elems = g_new0(VirtQueueElement, queue_size);
return &vdev->vq[i];
}
void virtio_delete_queue(VirtQueue *vq)
{
vq->vring.num = 0;
vq->vring.num_default = 0;
vq->handle_output = NULL;
g_free(vq->used_elems);
vq->used_elems = NULL;
virtio_virtqueue_reset_region_cache(vq);
}
void virtio_del_queue(VirtIODevice *vdev, int n)
{
if (n < 0 || n >= VIRTIO_QUEUE_MAX) {
abort();
}
virtio_delete_queue(&vdev->vq[n]);
}
static void virtio_set_isr(VirtIODevice *vdev, int value)
{
uint8_t old = qatomic_read(&vdev->isr);
/* Do not write ISR if it does not change, so that its cacheline remains
* shared in the common case where the guest does not read it.
*/
if ((old & value) != value) {
qatomic_or(&vdev->isr, value);
}
}
/* Called within rcu_read_lock(). */
static bool virtio_split_should_notify(VirtIODevice *vdev, VirtQueue *vq)
{
uint16_t old, new;
bool v;
/* We need to expose used array entries before checking used event. */
smp_mb();
/* Always notify when queue is empty (when feature acknowledge) */
if (virtio_vdev_has_feature(vdev, VIRTIO_F_NOTIFY_ON_EMPTY) &&
!vq->inuse && virtio_queue_empty(vq)) {
return true;
}
if (!virtio_vdev_has_feature(vdev, VIRTIO_RING_F_EVENT_IDX)) {
return !(vring_avail_flags(vq) & VRING_AVAIL_F_NO_INTERRUPT);
}
v = vq->signalled_used_valid;
vq->signalled_used_valid = true;
old = vq->signalled_used;
new = vq->signalled_used = vq->used_idx;
return !v || vring_need_event(vring_get_used_event(vq), new, old);
}
static bool vring_packed_need_event(VirtQueue *vq, bool wrap,
uint16_t off_wrap, uint16_t new,
uint16_t old)
{
int off = off_wrap & ~(1 << 15);
if (wrap != off_wrap >> 15) {
off -= vq->vring.num;
}
return vring_need_event(off, new, old);
}
/* Called within rcu_read_lock(). */
static bool virtio_packed_should_notify(VirtIODevice *vdev, VirtQueue *vq)
{
VRingPackedDescEvent e;
uint16_t old, new;
bool v;
VRingMemoryRegionCaches *caches;
caches = vring_get_region_caches(vq);
if (!caches) {
return false;
}
vring_packed_event_read(vdev, &caches->avail, &e);
old = vq->signalled_used;
new = vq->signalled_used = vq->used_idx;
v = vq->signalled_used_valid;
vq->signalled_used_valid = true;
if (e.flags == VRING_PACKED_EVENT_FLAG_DISABLE) {
return false;
} else if (e.flags == VRING_PACKED_EVENT_FLAG_ENABLE) {
return true;
}
return !v || vring_packed_need_event(vq, vq->used_wrap_counter,
e.off_wrap, new, old);
}
/* Called within rcu_read_lock(). */
static bool virtio_should_notify(VirtIODevice *vdev, VirtQueue *vq)
{
if (virtio_vdev_has_feature(vdev, VIRTIO_F_RING_PACKED)) {
return virtio_packed_should_notify(vdev, vq);
} else {
return virtio_split_should_notify(vdev, vq);
}
}
void virtio_notify_irqfd(VirtIODevice *vdev, VirtQueue *vq)
{
WITH_RCU_READ_LOCK_GUARD() {
if (!virtio_should_notify(vdev, vq)) {
return;
}
}
trace_virtio_notify_irqfd(vdev, vq);
/*
* virtio spec 1.0 says ISR bit 0 should be ignored with MSI, but
* windows drivers included in virtio-win 1.8.0 (circa 2015) are
* incorrectly polling this bit during crashdump and hibernation
* in MSI mode, causing a hang if this bit is never updated.
* Recent releases of Windows do not really shut down, but rather
* log out and hibernate to make the next startup faster. Hence,
* this manifested as a more serious hang during shutdown with
*
* Next driver release from 2016 fixed this problem, so working around it
* is not a must, but it's easy to do so let's do it here.
*
* Note: it's safe to update ISR from any thread as it was switched
* to an atomic operation.
*/
virtio_set_isr(vq->vdev, 0x1);
event_notifier_set(&vq->guest_notifier);
}
static void virtio_irq(VirtQueue *vq)
{
virtio_set_isr(vq->vdev, 0x1);
virtio_notify_vector(vq->vdev, vq->vector);
}
void virtio_notify(VirtIODevice *vdev, VirtQueue *vq)
{
WITH_RCU_READ_LOCK_GUARD() {
if (!virtio_should_notify(vdev, vq)) {
return;
}
}
trace_virtio_notify(vdev, vq);
virtio_irq(vq);
}
void virtio_notify_config(VirtIODevice *vdev)
{
if (!(vdev->status & VIRTIO_CONFIG_S_DRIVER_OK))
return;
virtio_set_isr(vdev, 0x3);
vdev->generation++;
virtio_notify_vector(vdev, vdev->config_vector);
}
static bool virtio_device_endian_needed(void *opaque)
{
VirtIODevice *vdev = opaque;
assert(vdev->device_endian != VIRTIO_DEVICE_ENDIAN_UNKNOWN);
if (!virtio_vdev_has_feature(vdev, VIRTIO_F_VERSION_1)) {
return vdev->device_endian != virtio_default_endian();
}
/* Devices conforming to VIRTIO 1.0 or later are always LE. */
return vdev->device_endian != VIRTIO_DEVICE_ENDIAN_LITTLE;
}
static bool virtio_64bit_features_needed(void *opaque)
{
VirtIODevice *vdev = opaque;
return (vdev->host_features >> 32) != 0;
}
static bool virtio_virtqueue_needed(void *opaque)
{
VirtIODevice *vdev = opaque;
return virtio_host_has_feature(vdev, VIRTIO_F_VERSION_1);
}
static bool virtio_packed_virtqueue_needed(void *opaque)
{
VirtIODevice *vdev = opaque;
return virtio_host_has_feature(vdev, VIRTIO_F_RING_PACKED);
}
static bool virtio_ringsize_needed(void *opaque)
{
VirtIODevice *vdev = opaque;
int i;
for (i = 0; i < VIRTIO_QUEUE_MAX; i++) {
if (vdev->vq[i].vring.num != vdev->vq[i].vring.num_default) {
return true;
}
}
return false;
}
static bool virtio_extra_state_needed(void *opaque)
{
VirtIODevice *vdev = opaque;
BusState *qbus = qdev_get_parent_bus(DEVICE(vdev));
VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
return k->has_extra_state &&
k->has_extra_state(qbus->parent);
}
static bool virtio_broken_needed(void *opaque)
{
VirtIODevice *vdev = opaque;
return vdev->broken;
}
static bool virtio_started_needed(void *opaque)
{
VirtIODevice *vdev = opaque;
return vdev->started;
}
static bool virtio_disabled_needed(void *opaque)
{
VirtIODevice *vdev = opaque;
return vdev->disabled;
}
static const VMStateDescription vmstate_virtqueue = {
.name = "virtqueue_state",
.version_id = 1,
.minimum_version_id = 1,
.fields = (VMStateField[]) {
VMSTATE_UINT64(vring.avail, struct VirtQueue),
VMSTATE_UINT64(vring.used, struct VirtQueue),
VMSTATE_END_OF_LIST()
}
};
static const VMStateDescription vmstate_packed_virtqueue = {
.name = "packed_virtqueue_state",
.version_id = 1,
.minimum_version_id = 1,
.fields = (VMStateField[]) {
VMSTATE_UINT16(last_avail_idx, struct VirtQueue),
VMSTATE_BOOL(last_avail_wrap_counter, struct VirtQueue),
VMSTATE_UINT16(used_idx, struct VirtQueue),
VMSTATE_BOOL(used_wrap_counter, struct VirtQueue),
VMSTATE_UINT32(inuse, struct VirtQueue),
VMSTATE_END_OF_LIST()
}
};
static const VMStateDescription vmstate_virtio_virtqueues = {
.name = "virtio/virtqueues",
.version_id = 1,
.minimum_version_id = 1,
.needed = &virtio_virtqueue_needed,
.fields = (VMStateField[]) {
VMSTATE_STRUCT_VARRAY_POINTER_KNOWN(vq, struct VirtIODevice,
VIRTIO_QUEUE_MAX, 0, vmstate_virtqueue, VirtQueue),
VMSTATE_END_OF_LIST()
}
};
static const VMStateDescription vmstate_virtio_packed_virtqueues = {
.name = "virtio/packed_virtqueues",
.version_id = 1,
.minimum_version_id = 1,
.needed = &virtio_packed_virtqueue_needed,
.fields = (VMStateField[]) {
VMSTATE_STRUCT_VARRAY_POINTER_KNOWN(vq, struct VirtIODevice,
VIRTIO_QUEUE_MAX, 0, vmstate_packed_virtqueue, VirtQueue),
VMSTATE_END_OF_LIST()
}
};
static const VMStateDescription vmstate_ringsize = {
.name = "ringsize_state",
.version_id = 1,
.minimum_version_id = 1,
.fields = (VMStateField[]) {
VMSTATE_UINT32(vring.num_default, struct VirtQueue),
VMSTATE_END_OF_LIST()
}
};
static const VMStateDescription vmstate_virtio_ringsize = {
.name = "virtio/ringsize",
.version_id = 1,
.minimum_version_id = 1,
.needed = &virtio_ringsize_needed,
.fields = (VMStateField[]) {
VMSTATE_STRUCT_VARRAY_POINTER_KNOWN(vq, struct VirtIODevice,
VIRTIO_QUEUE_MAX, 0, vmstate_ringsize, VirtQueue),
VMSTATE_END_OF_LIST()
}
};
static int get_extra_state(QEMUFile *f, void *pv, size_t size,
const VMStateField *field)
{
VirtIODevice *vdev = pv;
BusState *qbus = qdev_get_parent_bus(DEVICE(vdev));
VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
if (!k->load_extra_state) {
return -1;
} else {
return k->load_extra_state(qbus->parent, f);
}
}
static int put_extra_state(QEMUFile *f, void *pv, size_t size,
const VMStateField *field, JSONWriter *vmdesc)
{
VirtIODevice *vdev = pv;
BusState *qbus = qdev_get_parent_bus(DEVICE(vdev));
VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
k->save_extra_state(qbus->parent, f);
return 0;
}
static const VMStateInfo vmstate_info_extra_state = {
.name = "virtqueue_extra_state",
.get = get_extra_state,
.put = put_extra_state,
};
static const VMStateDescription vmstate_virtio_extra_state = {
.name = "virtio/extra_state",
.version_id = 1,
.minimum_version_id = 1,
.needed = &virtio_extra_state_needed,
.fields = (VMStateField[]) {
{
.name = "extra_state",
.version_id = 0,
.field_exists = NULL,
.size = 0,
.info = &vmstate_info_extra_state,
.flags = VMS_SINGLE,
.offset = 0,
},
VMSTATE_END_OF_LIST()
}
};
static const VMStateDescription vmstate_virtio_device_endian = {
.name = "virtio/device_endian",
.version_id = 1,
.minimum_version_id = 1,
.needed = &virtio_device_endian_needed,
.fields = (VMStateField[]) {
VMSTATE_UINT8(device_endian, VirtIODevice),
VMSTATE_END_OF_LIST()
}
};
static const VMStateDescription vmstate_virtio_64bit_features = {
.name = "virtio/64bit_features",
.version_id = 1,
.minimum_version_id = 1,
.needed = &virtio_64bit_features_needed,
.fields = (VMStateField[]) {
VMSTATE_UINT64(guest_features, VirtIODevice),
VMSTATE_END_OF_LIST()
}
};
static const VMStateDescription vmstate_virtio_broken = {
.name = "virtio/broken",
.version_id = 1,
.minimum_version_id = 1,
.needed = &virtio_broken_needed,
.fields = (VMStateField[]) {
VMSTATE_BOOL(broken, VirtIODevice),
VMSTATE_END_OF_LIST()
}
};
static const VMStateDescription vmstate_virtio_started = {
.name = "virtio/started",
.version_id = 1,
.minimum_version_id = 1,
.needed = &virtio_started_needed,
.fields = (VMStateField[]) {
VMSTATE_BOOL(started, VirtIODevice),
VMSTATE_END_OF_LIST()
}
};
static const VMStateDescription vmstate_virtio_disabled = {
.name = "virtio/disabled",
.version_id = 1,
.minimum_version_id = 1,
.needed = &virtio_disabled_needed,
.fields = (VMStateField[]) {
VMSTATE_BOOL(disabled, VirtIODevice),
VMSTATE_END_OF_LIST()
}
};
static const VMStateDescription vmstate_virtio = {
.name = "virtio",
.version_id = 1,
.minimum_version_id = 1,
.fields = (VMStateField[]) {
VMSTATE_END_OF_LIST()
},
.subsections = (const VMStateDescription*[]) {
&vmstate_virtio_device_endian,
&vmstate_virtio_64bit_features,
&vmstate_virtio_virtqueues,
&vmstate_virtio_ringsize,
&vmstate_virtio_broken,
&vmstate_virtio_extra_state,
&vmstate_virtio_started,
&vmstate_virtio_packed_virtqueues,
&vmstate_virtio_disabled,
NULL
}
};
int virtio_save(VirtIODevice *vdev, QEMUFile *f)
{
BusState *qbus = qdev_get_parent_bus(DEVICE(vdev));
VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
VirtioDeviceClass *vdc = VIRTIO_DEVICE_GET_CLASS(vdev);
uint32_t guest_features_lo = (vdev->guest_features & 0xffffffff);
int i;
if (k->save_config) {
k->save_config(qbus->parent, f);
}
qemu_put_8s(f, &vdev->status);
qemu_put_8s(f, &vdev->isr);
qemu_put_be16s(f, &vdev->queue_sel);
qemu_put_be32s(f, &guest_features_lo);
qemu_put_be32(f, vdev->config_len);
qemu_put_buffer(f, vdev->config, vdev->config_len);
for (i = 0; i < VIRTIO_QUEUE_MAX; i++) {
if (vdev->vq[i].vring.num == 0)
break;
}
qemu_put_be32(f, i);
for (i = 0; i < VIRTIO_QUEUE_MAX; i++) {
if (vdev->vq[i].vring.num == 0)
break;
qemu_put_be32(f, vdev->vq[i].vring.num);
if (k->has_variable_vring_alignment) {
qemu_put_be32(f, vdev->vq[i].vring.align);
}
/*
* Save desc now, the rest of the ring addresses are saved in
* subsections for VIRTIO-1 devices.
*/
qemu_put_be64(f, vdev->vq[i].vring.desc);
qemu_put_be16s(f, &vdev->vq[i].last_avail_idx);
if (k->save_queue) {
k->save_queue(qbus->parent, i, f);
}
}
if (vdc->save != NULL) {
vdc->save(vdev, f);
}
if (vdc->vmsd) {
int ret = vmstate_save_state(f, vdc->vmsd, vdev, NULL);
if (ret) {
return ret;
}
}
/* Subsections */
return vmstate_save_state(f, &vmstate_virtio, vdev, NULL);
}
/* A wrapper for use as a VMState .put function */
static int virtio_device_put(QEMUFile *f, void *opaque, size_t size,
const VMStateField *field, JSONWriter *vmdesc)
{
return virtio_save(VIRTIO_DEVICE(opaque), f);
}
/* A wrapper for use as a VMState .get function */
static int virtio_device_get(QEMUFile *f, void *opaque, size_t size,
const VMStateField *field)
{
VirtIODevice *vdev = VIRTIO_DEVICE(opaque);
DeviceClass *dc = DEVICE_CLASS(VIRTIO_DEVICE_GET_CLASS(vdev));
return virtio_load(vdev, f, dc->vmsd->version_id);
}
const VMStateInfo virtio_vmstate_info = {
.name = "virtio",
.get = virtio_device_get,
.put = virtio_device_put,
};
static int virtio_set_features_nocheck(VirtIODevice *vdev, uint64_t val)
{
VirtioDeviceClass *k = VIRTIO_DEVICE_GET_CLASS(vdev);
bool bad = (val & ~(vdev->host_features)) != 0;
val &= vdev->host_features;
if (k->set_features) {
k->set_features(vdev, val);
}
vdev->guest_features = val;
return bad ? -1 : 0;
}
int virtio_set_features(VirtIODevice *vdev, uint64_t val)
{
int ret;
/*
* The driver must not attempt to set features after feature negotiation
* has finished.
*/
if (vdev->status & VIRTIO_CONFIG_S_FEATURES_OK) {
return -EINVAL;
}
ret = virtio_set_features_nocheck(vdev, val);
if (virtio_vdev_has_feature(vdev, VIRTIO_RING_F_EVENT_IDX)) {
/* VIRTIO_RING_F_EVENT_IDX changes the size of the caches. */
int i;
for (i = 0; i < VIRTIO_QUEUE_MAX; i++) {
if (vdev->vq[i].vring.num != 0) {
virtio_init_region_cache(vdev, i);
}
}
}
if (!ret) {
if (!virtio_device_started(vdev, vdev->status) &&
!virtio_vdev_has_feature(vdev, VIRTIO_F_VERSION_1)) {
vdev->start_on_kick = true;
}
}
return ret;
}
size_t virtio_feature_get_config_size(const VirtIOFeature *feature_sizes,
uint64_t host_features)
{
size_t config_size = 0;
int i;
for (i = 0; feature_sizes[i].flags != 0; i++) {
if (host_features & feature_sizes[i].flags) {
config_size = MAX(feature_sizes[i].end, config_size);
}
}
return config_size;
}
int virtio_load(VirtIODevice *vdev, QEMUFile *f, int version_id)
{
int i, ret;
int32_t config_len;
uint32_t num;
uint32_t features;
BusState *qbus = qdev_get_parent_bus(DEVICE(vdev));
VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
VirtioDeviceClass *vdc = VIRTIO_DEVICE_GET_CLASS(vdev);
/*
* We poison the endianness to ensure it does not get used before
* subsections have been loaded.
*/
vdev->device_endian = VIRTIO_DEVICE_ENDIAN_UNKNOWN;
if (k->load_config) {
ret = k->load_config(qbus->parent, f);
if (ret)
return ret;
}
qemu_get_8s(f, &vdev->status);
qemu_get_8s(f, &vdev->isr);
qemu_get_be16s(f, &vdev->queue_sel);
if (vdev->queue_sel >= VIRTIO_QUEUE_MAX) {
return -1;
}
qemu_get_be32s(f, &features);
/*
* Temporarily set guest_features low bits - needed by
* virtio net load code testing for VIRTIO_NET_F_CTRL_GUEST_OFFLOADS
* VIRTIO_NET_F_GUEST_ANNOUNCE and VIRTIO_NET_F_CTRL_VQ.
*
* Note: devices should always test host features in future - don't create
* new dependencies like this.
*/
vdev->guest_features = features;
config_len = qemu_get_be32(f);
/*
* There are cases where the incoming config can be bigger or smaller
* than what we have; so load what we have space for, and skip
* any excess that's in the stream.
*/
qemu_get_buffer(f, vdev->config, MIN(config_len, vdev->config_len));
while (config_len > vdev->config_len) {
qemu_get_byte(f);
config_len--;
}
num = qemu_get_be32(f);
if (num > VIRTIO_QUEUE_MAX) {
error_report("Invalid number of virtqueues: 0x%x", num);
return -1;
}
for (i = 0; i < num; i++) {
vdev->vq[i].vring.num = qemu_get_be32(f);
if (k->has_variable_vring_alignment) {
vdev->vq[i].vring.align = qemu_get_be32(f);
}
vdev->vq[i].vring.desc = qemu_get_be64(f);
qemu_get_be16s(f, &vdev->vq[i].last_avail_idx);
vdev->vq[i].signalled_used_valid = false;
vdev->vq[i].notification = true;
if (!vdev->vq[i].vring.desc && vdev->vq[i].last_avail_idx) {
error_report("VQ %d address 0x0 "
"inconsistent with Host index 0x%x",
i, vdev->vq[i].last_avail_idx);
return -1;
}
if (k->load_queue) {
ret = k->load_queue(qbus->parent, i, f);
if (ret)
return ret;
}
}
virtio_notify_vector(vdev, VIRTIO_NO_VECTOR);
if (vdc->load != NULL) {
ret = vdc->load(vdev, f, version_id);
if (ret) {
return ret;
}
}
if (vdc->vmsd) {
ret = vmstate_load_state(f, vdc->vmsd, vdev, version_id);
if (ret) {
return ret;
}
}
/* Subsections */
ret = vmstate_load_state(f, &vmstate_virtio, vdev, 1);
if (ret) {
return ret;
}
if (vdev->device_endian == VIRTIO_DEVICE_ENDIAN_UNKNOWN) {
vdev->device_endian = virtio_default_endian();
}
if (virtio_64bit_features_needed(vdev)) {
/*
* Subsection load filled vdev->guest_features. Run them
* through virtio_set_features to sanity-check them against
* host_features.
*/
uint64_t features64 = vdev->guest_features;
if (virtio_set_features_nocheck(vdev, features64) < 0) {
error_report("Features 0x%" PRIx64 " unsupported. "
"Allowed features: 0x%" PRIx64,
features64, vdev->host_features);
return -1;
}
} else {
if (virtio_set_features_nocheck(vdev, features) < 0) {
error_report("Features 0x%x unsupported. "
"Allowed features: 0x%" PRIx64,
features, vdev->host_features);
return -1;
}
}
if (!virtio_device_started(vdev, vdev->status) &&
!virtio_vdev_has_feature(vdev, VIRTIO_F_VERSION_1)) {
vdev->start_on_kick = true;
}
RCU_READ_LOCK_GUARD();
for (i = 0; i < num; i++) {
if (vdev->vq[i].vring.desc) {
uint16_t nheads;
/*
* VIRTIO-1 devices migrate desc, used, and avail ring addresses so
* only the region cache needs to be set up. Legacy devices need
* to calculate used and avail ring addresses based on the desc
* address.
*/
if (virtio_vdev_has_feature(vdev, VIRTIO_F_VERSION_1)) {
virtio_init_region_cache(vdev, i);
} else {
virtio_queue_update_rings(vdev, i);
}
if (virtio_vdev_has_feature(vdev, VIRTIO_F_RING_PACKED)) {
vdev->vq[i].shadow_avail_idx = vdev->vq[i].last_avail_idx;
vdev->vq[i].shadow_avail_wrap_counter =
vdev->vq[i].last_avail_wrap_counter;
continue;
}
nheads = vring_avail_idx(&vdev->vq[i]) - vdev->vq[i].last_avail_idx;
/* Check it isn't doing strange things with descriptor numbers. */
if (nheads > vdev->vq[i].vring.num) {
virtio_error(vdev, "VQ %d size 0x%x Guest index 0x%x "
"inconsistent with Host index 0x%x: delta 0x%x",
i, vdev->vq[i].vring.num,
vring_avail_idx(&vdev->vq[i]),
vdev->vq[i].last_avail_idx, nheads);
vdev->vq[i].used_idx = 0;
vdev->vq[i].shadow_avail_idx = 0;
vdev->vq[i].inuse = 0;
continue;
}
vdev->vq[i].used_idx = vring_used_idx(&vdev->vq[i]);
vdev->vq[i].shadow_avail_idx = vring_avail_idx(&vdev->vq[i]);
/*
* Some devices migrate VirtQueueElements that have been popped
* from the avail ring but not yet returned to the used ring.
* Since max ring size < UINT16_MAX it's safe to use modulo
* UINT16_MAX + 1 subtraction.
*/
vdev->vq[i].inuse = (uint16_t)(vdev->vq[i].last_avail_idx -
vdev->vq[i].used_idx);
if (vdev->vq[i].inuse > vdev->vq[i].vring.num) {
error_report("VQ %d size 0x%x < last_avail_idx 0x%x - "
"used_idx 0x%x",
i, vdev->vq[i].vring.num,
vdev->vq[i].last_avail_idx,
vdev->vq[i].used_idx);
return -1;
}
}
}
if (vdc->post_load) {
ret = vdc->post_load(vdev);
if (ret) {
return ret;
}
}
return 0;
}
void virtio_cleanup(VirtIODevice *vdev)
{
qemu_del_vm_change_state_handler(vdev->vmstate);
}
static void virtio_vmstate_change(void *opaque, bool running, RunState state)
{
VirtIODevice *vdev = opaque;
BusState *qbus = qdev_get_parent_bus(DEVICE(vdev));
VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
bool backend_run = running && virtio_device_started(vdev, vdev->status);
vdev->vm_running = running;
if (backend_run) {
virtio_set_status(vdev, vdev->status);
}
if (k->vmstate_change) {
k->vmstate_change(qbus->parent, backend_run);
}
if (!backend_run) {
virtio_set_status(vdev, vdev->status);
}
}
void virtio_instance_init_common(Object *proxy_obj, void *data,
size_t vdev_size, const char *vdev_name)
{
DeviceState *vdev = data;
object_initialize_child_with_props(proxy_obj, "virtio-backend", vdev,
vdev_size, vdev_name, &error_abort,
NULL);
qdev_alias_all_properties(vdev, proxy_obj);
}
void virtio_init(VirtIODevice *vdev, const char *name,
uint16_t device_id, size_t config_size)
{
BusState *qbus = qdev_get_parent_bus(DEVICE(vdev));
VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
int i;
int nvectors = k->query_nvectors ? k->query_nvectors(qbus->parent) : 0;
if (nvectors) {
vdev->vector_queues =
g_malloc0(sizeof(*vdev->vector_queues) * nvectors);
}
vdev->start_on_kick = false;
vdev->started = false;
vdev->device_id = device_id;
vdev->status = 0;
qatomic_set(&vdev->isr, 0);
vdev->queue_sel = 0;
vdev->config_vector = VIRTIO_NO_VECTOR;
vdev->vq = g_new0(VirtQueue, VIRTIO_QUEUE_MAX);
vdev->vm_running = runstate_is_running();
vdev->broken = false;
for (i = 0; i < VIRTIO_QUEUE_MAX; i++) {
vdev->vq[i].vector = VIRTIO_NO_VECTOR;
vdev->vq[i].vdev = vdev;
vdev->vq[i].queue_index = i;
vdev->vq[i].host_notifier_enabled = false;
}
vdev->name = name;
vdev->config_len = config_size;
if (vdev->config_len) {
vdev->config = g_malloc0(config_size);
} else {
vdev->config = NULL;
}
vdev->vmstate = qdev_add_vm_change_state_handler(DEVICE(vdev),
virtio_vmstate_change, vdev);
vdev->device_endian = virtio_default_endian();
vdev->use_guest_notifier_mask = true;
}
/*
* Only devices that have already been around prior to defining the virtio
* standard support legacy mode; this includes devices not specified in the
* standard. All newer devices conform to the virtio standard only.
*/
bool virtio_legacy_allowed(VirtIODevice *vdev)
{
switch (vdev->device_id) {
case VIRTIO_ID_NET:
case VIRTIO_ID_BLOCK:
case VIRTIO_ID_CONSOLE:
case VIRTIO_ID_RNG:
case VIRTIO_ID_BALLOON:
case VIRTIO_ID_RPMSG:
case VIRTIO_ID_SCSI:
case VIRTIO_ID_9P:
case VIRTIO_ID_RPROC_SERIAL:
case VIRTIO_ID_CAIF:
return true;
default:
return false;
}
}
bool virtio_legacy_check_disabled(VirtIODevice *vdev)
{
return vdev->disable_legacy_check;
}
hwaddr virtio_queue_get_desc_addr(VirtIODevice *vdev, int n)
{
return vdev->vq[n].vring.desc;
}
bool virtio_queue_enabled_legacy(VirtIODevice *vdev, int n)
{
return virtio_queue_get_desc_addr(vdev, n) != 0;
}
bool virtio_queue_enabled(VirtIODevice *vdev, int n)
{
BusState *qbus = qdev_get_parent_bus(DEVICE(vdev));
VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
if (k->queue_enabled) {
return k->queue_enabled(qbus->parent, n);
}
return virtio_queue_enabled_legacy(vdev, n);
}
hwaddr virtio_queue_get_avail_addr(VirtIODevice *vdev, int n)
{
return vdev->vq[n].vring.avail;
}
hwaddr virtio_queue_get_used_addr(VirtIODevice *vdev, int n)
{
return vdev->vq[n].vring.used;
}
hwaddr virtio_queue_get_desc_size(VirtIODevice *vdev, int n)
{
return sizeof(VRingDesc) * vdev->vq[n].vring.num;
}
hwaddr virtio_queue_get_avail_size(VirtIODevice *vdev, int n)
{
int s;
if (virtio_vdev_has_feature(vdev, VIRTIO_F_RING_PACKED)) {
return sizeof(struct VRingPackedDescEvent);
}
s = virtio_vdev_has_feature(vdev, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
return offsetof(VRingAvail, ring) +
sizeof(uint16_t) * vdev->vq[n].vring.num + s;
}
hwaddr virtio_queue_get_used_size(VirtIODevice *vdev, int n)
{
int s;
if (virtio_vdev_has_feature(vdev, VIRTIO_F_RING_PACKED)) {
return sizeof(struct VRingPackedDescEvent);
}
s = virtio_vdev_has_feature(vdev, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
return offsetof(VRingUsed, ring) +
sizeof(VRingUsedElem) * vdev->vq[n].vring.num + s;
}
static unsigned int virtio_queue_packed_get_last_avail_idx(VirtIODevice *vdev,
int n)
{
unsigned int avail, used;
avail = vdev->vq[n].last_avail_idx;
avail |= ((uint16_t)vdev->vq[n].last_avail_wrap_counter) << 15;
used = vdev->vq[n].used_idx;
used |= ((uint16_t)vdev->vq[n].used_wrap_counter) << 15;
return avail | used << 16;
}
static uint16_t virtio_queue_split_get_last_avail_idx(VirtIODevice *vdev,
int n)
{
return vdev->vq[n].last_avail_idx;
}
unsigned int virtio_queue_get_last_avail_idx(VirtIODevice *vdev, int n)
{
if (virtio_vdev_has_feature(vdev, VIRTIO_F_RING_PACKED)) {
return virtio_queue_packed_get_last_avail_idx(vdev, n);
} else {
return virtio_queue_split_get_last_avail_idx(vdev, n);
}
}
static void virtio_queue_packed_set_last_avail_idx(VirtIODevice *vdev,
int n, unsigned int idx)
{
struct VirtQueue *vq = &vdev->vq[n];
vq->last_avail_idx = vq->shadow_avail_idx = idx & 0x7fff;
vq->last_avail_wrap_counter =
vq->shadow_avail_wrap_counter = !!(idx & 0x8000);
idx >>= 16;
vq->used_idx = idx & 0x7ffff;
vq->used_wrap_counter = !!(idx & 0x8000);
}
static void virtio_queue_split_set_last_avail_idx(VirtIODevice *vdev,
int n, unsigned int idx)
{
vdev->vq[n].last_avail_idx = idx;
vdev->vq[n].shadow_avail_idx = idx;
}
void virtio_queue_set_last_avail_idx(VirtIODevice *vdev, int n,
unsigned int idx)
{
if (virtio_vdev_has_feature(vdev, VIRTIO_F_RING_PACKED)) {
virtio_queue_packed_set_last_avail_idx(vdev, n, idx);
} else {
virtio_queue_split_set_last_avail_idx(vdev, n, idx);
}
}
static void virtio_queue_packed_restore_last_avail_idx(VirtIODevice *vdev,
int n)
{
/* We don't have a reference like avail idx in shared memory */
return;
}
static void virtio_queue_split_restore_last_avail_idx(VirtIODevice *vdev,
int n)
{
RCU_READ_LOCK_GUARD();
if (vdev->vq[n].vring.desc) {
vdev->vq[n].last_avail_idx = vring_used_idx(&vdev->vq[n]);
vdev->vq[n].shadow_avail_idx = vdev->vq[n].last_avail_idx;
}
}
void virtio_queue_restore_last_avail_idx(VirtIODevice *vdev, int n)
{
if (virtio_vdev_has_feature(vdev, VIRTIO_F_RING_PACKED)) {
virtio_queue_packed_restore_last_avail_idx(vdev, n);
} else {
virtio_queue_split_restore_last_avail_idx(vdev, n);
}
}
static void virtio_queue_packed_update_used_idx(VirtIODevice *vdev, int n)
{
/* used idx was updated through set_last_avail_idx() */
return;
}
static void virtio_split_packed_update_used_idx(VirtIODevice *vdev, int n)
{
RCU_READ_LOCK_GUARD();
if (vdev->vq[n].vring.desc) {
vdev->vq[n].used_idx = vring_used_idx(&vdev->vq[n]);
}
}
void virtio_queue_update_used_idx(VirtIODevice *vdev, int n)
{
if (virtio_vdev_has_feature(vdev, VIRTIO_F_RING_PACKED)) {
return virtio_queue_packed_update_used_idx(vdev, n);
} else {
return virtio_split_packed_update_used_idx(vdev, n);
}
}
void virtio_queue_invalidate_signalled_used(VirtIODevice *vdev, int n)
{
vdev->vq[n].signalled_used_valid = false;
}
VirtQueue *virtio_get_queue(VirtIODevice *vdev, int n)
{
return vdev->vq + n;
}
uint16_t virtio_get_queue_index(VirtQueue *vq)
{
return vq->queue_index;
}
static void virtio_queue_guest_notifier_read(EventNotifier *n)
{
VirtQueue *vq = container_of(n, VirtQueue, guest_notifier);
if (event_notifier_test_and_clear(n)) {
virtio_irq(vq);
}
}
void virtio_queue_set_guest_notifier_fd_handler(VirtQueue *vq, bool assign,
bool with_irqfd)
{
if (assign && !with_irqfd) {
event_notifier_set_handler(&vq->guest_notifier,
virtio_queue_guest_notifier_read);
} else {
event_notifier_set_handler(&vq->guest_notifier, NULL);
}
if (!assign) {
/* Test and clear notifier before closing it,
* in case poll callback didn't have time to run. */
virtio_queue_guest_notifier_read(&vq->guest_notifier);
}
}
EventNotifier *virtio_queue_get_guest_notifier(VirtQueue *vq)
{
return &vq->guest_notifier;
}
static void virtio_queue_host_notifier_aio_poll_begin(EventNotifier *n)
{
VirtQueue *vq = container_of(n, VirtQueue, host_notifier);
virtio_queue_set_notification(vq, 0);
}
static bool virtio_queue_host_notifier_aio_poll(void *opaque)
{
EventNotifier *n = opaque;
VirtQueue *vq = container_of(n, VirtQueue, host_notifier);
return vq->vring.desc && !virtio_queue_empty(vq);
}
static void virtio_queue_host_notifier_aio_poll_ready(EventNotifier *n)
{
VirtQueue *vq = container_of(n, VirtQueue, host_notifier);
virtio_queue_notify_vq(vq);
}
static void virtio_queue_host_notifier_aio_poll_end(EventNotifier *n)
{
VirtQueue *vq = container_of(n, VirtQueue, host_notifier);
/* Caller polls once more after this to catch requests that race with us */
virtio_queue_set_notification(vq, 1);
}
void virtio_queue_aio_attach_host_notifier(VirtQueue *vq, AioContext *ctx)
{
aio_set_event_notifier(ctx, &vq->host_notifier, true,
virtio_queue_host_notifier_read,
virtio_queue_host_notifier_aio_poll,
virtio_queue_host_notifier_aio_poll_ready);
aio_set_event_notifier_poll(ctx, &vq->host_notifier,
virtio_queue_host_notifier_aio_poll_begin,
virtio_queue_host_notifier_aio_poll_end);
}
/*
* Same as virtio_queue_aio_attach_host_notifier() but without polling. Use
* this for rx virtqueues and similar cases where the virtqueue handler
* function does not pop all elements. When the virtqueue is left non-empty
* polling consumes CPU cycles and should not be used.
*/
void virtio_queue_aio_attach_host_notifier_no_poll(VirtQueue *vq, AioContext *ctx)
{
aio_set_event_notifier(ctx, &vq->host_notifier, true,
virtio_queue_host_notifier_read,
NULL, NULL);
}
void virtio_queue_aio_detach_host_notifier(VirtQueue *vq, AioContext *ctx)
{
aio_set_event_notifier(ctx, &vq->host_notifier, true, NULL, NULL, NULL);
/* Test and clear notifier before after disabling event,
* in case poll callback didn't have time to run. */
virtio_queue_host_notifier_read(&vq->host_notifier);
}
void virtio_queue_host_notifier_read(EventNotifier *n)
{
VirtQueue *vq = container_of(n, VirtQueue, host_notifier);
if (event_notifier_test_and_clear(n)) {
virtio_queue_notify_vq(vq);
}
}
EventNotifier *virtio_queue_get_host_notifier(VirtQueue *vq)
{
return &vq->host_notifier;
}
void virtio_queue_set_host_notifier_enabled(VirtQueue *vq, bool enabled)
{
vq->host_notifier_enabled = enabled;
}
int virtio_queue_set_host_notifier_mr(VirtIODevice *vdev, int n,
MemoryRegion *mr, bool assign)
{
BusState *qbus = qdev_get_parent_bus(DEVICE(vdev));
VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
if (k->set_host_notifier_mr) {
return k->set_host_notifier_mr(qbus->parent, n, mr, assign);
}
return -1;
}
void virtio_device_set_child_bus_name(VirtIODevice *vdev, char *bus_name)
{
g_free(vdev->bus_name);
vdev->bus_name = g_strdup(bus_name);
}
void G_GNUC_PRINTF(2, 3) virtio_error(VirtIODevice *vdev, const char *fmt, ...)
{
va_list ap;
va_start(ap, fmt);
error_vreport(fmt, ap);
va_end(ap);
if (virtio_vdev_has_feature(vdev, VIRTIO_F_VERSION_1)) {
vdev->status = vdev->status | VIRTIO_CONFIG_S_NEEDS_RESET;
virtio_notify_config(vdev);
}
vdev->broken = true;
}
static void virtio_memory_listener_commit(MemoryListener *listener)
{
VirtIODevice *vdev = container_of(listener, VirtIODevice, listener);
int i;
for (i = 0; i < VIRTIO_QUEUE_MAX; i++) {
if (vdev->vq[i].vring.num == 0) {
break;
}
virtio_init_region_cache(vdev, i);
}
}
static void virtio_device_realize(DeviceState *dev, Error **errp)
{
VirtIODevice *vdev = VIRTIO_DEVICE(dev);
VirtioDeviceClass *vdc = VIRTIO_DEVICE_GET_CLASS(dev);
Error *err = NULL;
/* Devices should either use vmsd or the load/save methods */
assert(!vdc->vmsd || !vdc->load);
if (vdc->realize != NULL) {
vdc->realize(dev, &err);
if (err != NULL) {
error_propagate(errp, err);
return;
}
}
virtio_bus_device_plugged(vdev, &err);
if (err != NULL) {
error_propagate(errp, err);
vdc->unrealize(dev);
return;
}
vdev->listener.commit = virtio_memory_listener_commit;
vdev->listener.name = "virtio";
memory_listener_register(&vdev->listener, vdev->dma_as);
}
static void virtio_device_unrealize(DeviceState *dev)
{
VirtIODevice *vdev = VIRTIO_DEVICE(dev);
VirtioDeviceClass *vdc = VIRTIO_DEVICE_GET_CLASS(dev);
memory_listener_unregister(&vdev->listener);
virtio_bus_device_unplugged(vdev);
if (vdc->unrealize != NULL) {
vdc->unrealize(dev);
}
g_free(vdev->bus_name);
vdev->bus_name = NULL;
}
static void virtio_device_free_virtqueues(VirtIODevice *vdev)
{
int i;
if (!vdev->vq) {
return;
}
for (i = 0; i < VIRTIO_QUEUE_MAX; i++) {
if (vdev->vq[i].vring.num == 0) {
break;
}
virtio_virtqueue_reset_region_cache(&vdev->vq[i]);
}
g_free(vdev->vq);
}
static void virtio_device_instance_finalize(Object *obj)
{
VirtIODevice *vdev = VIRTIO_DEVICE(obj);
virtio_device_free_virtqueues(vdev);
g_free(vdev->config);
g_free(vdev->vector_queues);
}
static Property virtio_properties[] = {
DEFINE_VIRTIO_COMMON_FEATURES(VirtIODevice, host_features),
DEFINE_PROP_BOOL("use-started", VirtIODevice, use_started, true),
DEFINE_PROP_BOOL("use-disabled-flag", VirtIODevice, use_disabled_flag, true),
DEFINE_PROP_BOOL("x-disable-legacy-check", VirtIODevice,
disable_legacy_check, false),
DEFINE_PROP_END_OF_LIST(),
};
static int virtio_device_start_ioeventfd_impl(VirtIODevice *vdev)
{
VirtioBusState *qbus = VIRTIO_BUS(qdev_get_parent_bus(DEVICE(vdev)));
int i, n, r, err;
/*
* Batch all the host notifiers in a single transaction to avoid
* quadratic time complexity in address_space_update_ioeventfds().
*/
memory_region_transaction_begin();
for (n = 0; n < VIRTIO_QUEUE_MAX; n++) {
VirtQueue *vq = &vdev->vq[n];
if (!virtio_queue_get_num(vdev, n)) {
continue;
}
r = virtio_bus_set_host_notifier(qbus, n, true);
if (r < 0) {
err = r;
goto assign_error;
}
event_notifier_set_handler(&vq->host_notifier,
virtio_queue_host_notifier_read);
}
for (n = 0; n < VIRTIO_QUEUE_MAX; n++) {
/* Kick right away to begin processing requests already in vring */
VirtQueue *vq = &vdev->vq[n];
if (!vq->vring.num) {
continue;
}
event_notifier_set(&vq->host_notifier);
}
memory_region_transaction_commit();
return 0;
assign_error:
i = n; /* save n for a second iteration after transaction is committed. */
while (--n >= 0) {
VirtQueue *vq = &vdev->vq[n];
if (!virtio_queue_get_num(vdev, n)) {
continue;
}
event_notifier_set_handler(&vq->host_notifier, NULL);
r = virtio_bus_set_host_notifier(qbus, n, false);
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();
while (--i >= 0) {
if (!virtio_queue_get_num(vdev, i)) {
continue;
}
virtio_bus_cleanup_host_notifier(qbus, i);
}
return err;
}
int virtio_device_start_ioeventfd(VirtIODevice *vdev)
{
BusState *qbus = qdev_get_parent_bus(DEVICE(vdev));
VirtioBusState *vbus = VIRTIO_BUS(qbus);
return virtio_bus_start_ioeventfd(vbus);
}
static void virtio_device_stop_ioeventfd_impl(VirtIODevice *vdev)
{
VirtioBusState *qbus = VIRTIO_BUS(qdev_get_parent_bus(DEVICE(vdev)));
int n, 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 (n = 0; n < VIRTIO_QUEUE_MAX; n++) {
VirtQueue *vq = &vdev->vq[n];
if (!virtio_queue_get_num(vdev, n)) {
continue;
}
event_notifier_set_handler(&vq->host_notifier, NULL);
r = virtio_bus_set_host_notifier(qbus, n, false);
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 (n = 0; n < VIRTIO_QUEUE_MAX; n++) {
if (!virtio_queue_get_num(vdev, n)) {
continue;
}
virtio_bus_cleanup_host_notifier(qbus, n);
}
}
int virtio_device_grab_ioeventfd(VirtIODevice *vdev)
{
BusState *qbus = qdev_get_parent_bus(DEVICE(vdev));
VirtioBusState *vbus = VIRTIO_BUS(qbus);
return virtio_bus_grab_ioeventfd(vbus);
}
void virtio_device_release_ioeventfd(VirtIODevice *vdev)
{
BusState *qbus = qdev_get_parent_bus(DEVICE(vdev));
VirtioBusState *vbus = VIRTIO_BUS(qbus);
virtio_bus_release_ioeventfd(vbus);
}
static void virtio_device_class_init(ObjectClass *klass, void *data)
{
/* Set the default value here. */
VirtioDeviceClass *vdc = VIRTIO_DEVICE_CLASS(klass);
DeviceClass *dc = DEVICE_CLASS(klass);
dc->realize = virtio_device_realize;
dc->unrealize = virtio_device_unrealize;
dc->bus_type = TYPE_VIRTIO_BUS;
device_class_set_props(dc, virtio_properties);
vdc->start_ioeventfd = virtio_device_start_ioeventfd_impl;
vdc->stop_ioeventfd = virtio_device_stop_ioeventfd_impl;
vdc->legacy_features |= VIRTIO_LEGACY_FEATURES;
}
bool virtio_device_ioeventfd_enabled(VirtIODevice *vdev)
{
BusState *qbus = qdev_get_parent_bus(DEVICE(vdev));
VirtioBusState *vbus = VIRTIO_BUS(qbus);
return virtio_bus_ioeventfd_enabled(vbus);
}
static const TypeInfo virtio_device_info = {
.name = TYPE_VIRTIO_DEVICE,
.parent = TYPE_DEVICE,
.instance_size = sizeof(VirtIODevice),
.class_init = virtio_device_class_init,
.instance_finalize = virtio_device_instance_finalize,
.abstract = true,
.class_size = sizeof(VirtioDeviceClass),
};
static void virtio_register_types(void)
{
type_register_static(&virtio_device_info);
}
type_init(virtio_register_types)
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