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authorJason Wang <jasowang@redhat.com>2019-10-25 10:35:25 +0200
committerMichael S. Tsirkin <mst@redhat.com>2019-10-25 07:46:22 -0400
commit683f7665679c1e9ef64183c3636b8e13ce012cdc (patch)
tree27595092ad8b942975c904ca14fba4ec1666405c /hw/virtio
parent86044b24e865fb9596ed77a4d0f3af8b90a088a1 (diff)
virtio: event suppression support for packed ring
This patch implements event suppression through device/driver area. Please refer virtio specification for more information. Signed-off-by: Wei Xu <wexu@redhat.com> Signed-off-by: Jason Wang <jasowang@redhat.com> Signed-off-by: Eugenio PĂ©rez <eperezma@redhat.com> Message-Id: <20191025083527.30803-7-eperezma@redhat.com> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Diffstat (limited to 'hw/virtio')
-rw-r--r--hw/virtio/virtio.c142
1 files changed, 133 insertions, 9 deletions
diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index a694b4ab50..828c27de1f 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -240,6 +240,44 @@ static void vring_split_desc_read(VirtIODevice *vdev, VRingDesc *desc,
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);
+
+ address_space_read_cached(cache, off_flags, &e->flags,
+ sizeof(e->flags));
+ /* Make sure flags is seen before off_wrap */
+ smp_rmb();
+ address_space_read_cached(cache, off_off, &e->off_wrap,
+ sizeof(e->off_wrap));
+ virtio_tswap16s(vdev, &e->off_wrap);
+ 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_tswap16s(vdev, &off_wrap);
+ address_space_write_cached(cache, off, &off_wrap, sizeof(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_tswap16s(vdev, &flags);
+ address_space_write_cached(cache, off, &flags, sizeof(flags));
+ address_space_cache_invalidate(cache, off, sizeof(flags));
+}
+
/* Called within rcu_read_lock(). */
static VRingMemoryRegionCaches *vring_get_region_caches(struct VirtQueue *vq)
{
@@ -347,14 +385,8 @@ static inline void vring_set_avail_event(VirtQueue *vq, uint16_t val)
address_space_cache_invalidate(&caches->used, pa, sizeof(val));
}
-void virtio_queue_set_notification(VirtQueue *vq, int enable)
+static void virtio_queue_split_set_notification(VirtQueue *vq, int enable)
{
- vq->notification = enable;
-
- if (!vq->vring.desc) {
- return;
- }
-
rcu_read_lock();
if (virtio_vdev_has_feature(vq->vdev, VIRTIO_RING_F_EVENT_IDX)) {
vring_set_avail_event(vq, vring_avail_idx(vq));
@@ -370,6 +402,51 @@ void virtio_queue_set_notification(VirtQueue *vq, int enable)
rcu_read_unlock();
}
+static void virtio_queue_packed_set_notification(VirtQueue *vq, int enable)
+{
+ uint16_t off_wrap;
+ VRingPackedDescEvent e;
+ VRingMemoryRegionCaches *caches;
+
+ rcu_read_lock();
+ caches = vring_get_region_caches(vq);
+ 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();
+ }
+ rcu_read_unlock();
+}
+
+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;
@@ -2287,8 +2364,7 @@ static void virtio_set_isr(VirtIODevice *vdev, int value)
}
}
-/* Called within rcu_read_lock(). */
-static bool virtio_should_notify(VirtIODevice *vdev, VirtQueue *vq)
+static bool virtio_split_should_notify(VirtIODevice *vdev, VirtQueue *vq)
{
uint16_t old, new;
bool v;
@@ -2311,6 +2387,54 @@ static bool virtio_should_notify(VirtIODevice *vdev, VirtQueue *vq)
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);
+}
+
+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);
+ 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)
{
bool should_notify;