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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 Pérez <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>
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@ -240,6 +240,44 @@ static void vring_split_desc_read(VirtIODevice *vdev, VRingDesc *desc,
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virtio_tswap16s(vdev, &desc->next);
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}
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static void vring_packed_event_read(VirtIODevice *vdev,
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MemoryRegionCache *cache,
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VRingPackedDescEvent *e)
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{
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hwaddr off_off = offsetof(VRingPackedDescEvent, off_wrap);
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hwaddr off_flags = offsetof(VRingPackedDescEvent, flags);
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address_space_read_cached(cache, off_flags, &e->flags,
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sizeof(e->flags));
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/* Make sure flags is seen before off_wrap */
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smp_rmb();
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address_space_read_cached(cache, off_off, &e->off_wrap,
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sizeof(e->off_wrap));
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virtio_tswap16s(vdev, &e->off_wrap);
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virtio_tswap16s(vdev, &e->flags);
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}
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static void vring_packed_off_wrap_write(VirtIODevice *vdev,
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MemoryRegionCache *cache,
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uint16_t off_wrap)
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{
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hwaddr off = offsetof(VRingPackedDescEvent, off_wrap);
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virtio_tswap16s(vdev, &off_wrap);
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address_space_write_cached(cache, off, &off_wrap, sizeof(off_wrap));
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address_space_cache_invalidate(cache, off, sizeof(off_wrap));
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}
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static void vring_packed_flags_write(VirtIODevice *vdev,
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MemoryRegionCache *cache, uint16_t flags)
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{
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hwaddr off = offsetof(VRingPackedDescEvent, flags);
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virtio_tswap16s(vdev, &flags);
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address_space_write_cached(cache, off, &flags, sizeof(flags));
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address_space_cache_invalidate(cache, off, sizeof(flags));
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}
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/* Called within rcu_read_lock(). */
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static VRingMemoryRegionCaches *vring_get_region_caches(struct VirtQueue *vq)
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{
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@ -347,14 +385,8 @@ static inline void vring_set_avail_event(VirtQueue *vq, uint16_t val)
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address_space_cache_invalidate(&caches->used, pa, sizeof(val));
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}
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void virtio_queue_set_notification(VirtQueue *vq, int enable)
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static void virtio_queue_split_set_notification(VirtQueue *vq, int enable)
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{
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vq->notification = enable;
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if (!vq->vring.desc) {
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return;
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}
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rcu_read_lock();
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if (virtio_vdev_has_feature(vq->vdev, VIRTIO_RING_F_EVENT_IDX)) {
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vring_set_avail_event(vq, vring_avail_idx(vq));
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@ -370,6 +402,51 @@ void virtio_queue_set_notification(VirtQueue *vq, int enable)
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rcu_read_unlock();
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}
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static void virtio_queue_packed_set_notification(VirtQueue *vq, int enable)
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{
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uint16_t off_wrap;
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VRingPackedDescEvent e;
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VRingMemoryRegionCaches *caches;
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rcu_read_lock();
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caches = vring_get_region_caches(vq);
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vring_packed_event_read(vq->vdev, &caches->used, &e);
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if (!enable) {
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e.flags = VRING_PACKED_EVENT_FLAG_DISABLE;
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} else if (virtio_vdev_has_feature(vq->vdev, VIRTIO_RING_F_EVENT_IDX)) {
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off_wrap = vq->shadow_avail_idx | vq->shadow_avail_wrap_counter << 15;
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vring_packed_off_wrap_write(vq->vdev, &caches->used, off_wrap);
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/* Make sure off_wrap is wrote before flags */
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smp_wmb();
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e.flags = VRING_PACKED_EVENT_FLAG_DESC;
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} else {
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e.flags = VRING_PACKED_EVENT_FLAG_ENABLE;
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}
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vring_packed_flags_write(vq->vdev, &caches->used, e.flags);
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if (enable) {
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/* Expose avail event/used flags before caller checks the avail idx. */
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smp_mb();
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}
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rcu_read_unlock();
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}
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void virtio_queue_set_notification(VirtQueue *vq, int enable)
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{
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vq->notification = enable;
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if (!vq->vring.desc) {
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return;
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}
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if (virtio_vdev_has_feature(vq->vdev, VIRTIO_F_RING_PACKED)) {
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virtio_queue_packed_set_notification(vq, enable);
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} else {
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virtio_queue_split_set_notification(vq, enable);
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}
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}
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int virtio_queue_ready(VirtQueue *vq)
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{
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return vq->vring.avail != 0;
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@ -2287,8 +2364,7 @@ static void virtio_set_isr(VirtIODevice *vdev, int value)
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}
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}
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/* Called within rcu_read_lock(). */
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static bool virtio_should_notify(VirtIODevice *vdev, VirtQueue *vq)
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static bool virtio_split_should_notify(VirtIODevice *vdev, VirtQueue *vq)
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{
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uint16_t old, new;
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bool v;
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@ -2311,6 +2387,54 @@ static bool virtio_should_notify(VirtIODevice *vdev, VirtQueue *vq)
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return !v || vring_need_event(vring_get_used_event(vq), new, old);
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}
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static bool vring_packed_need_event(VirtQueue *vq, bool wrap,
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uint16_t off_wrap, uint16_t new,
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uint16_t old)
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{
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int off = off_wrap & ~(1 << 15);
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if (wrap != off_wrap >> 15) {
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off -= vq->vring.num;
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}
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return vring_need_event(off, new, old);
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}
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static bool virtio_packed_should_notify(VirtIODevice *vdev, VirtQueue *vq)
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{
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VRingPackedDescEvent e;
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uint16_t old, new;
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bool v;
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VRingMemoryRegionCaches *caches;
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caches = vring_get_region_caches(vq);
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vring_packed_event_read(vdev, &caches->avail, &e);
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old = vq->signalled_used;
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new = vq->signalled_used = vq->used_idx;
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v = vq->signalled_used_valid;
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vq->signalled_used_valid = true;
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if (e.flags == VRING_PACKED_EVENT_FLAG_DISABLE) {
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return false;
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} else if (e.flags == VRING_PACKED_EVENT_FLAG_ENABLE) {
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return true;
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}
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return !v || vring_packed_need_event(vq, vq->used_wrap_counter,
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e.off_wrap, new, old);
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}
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/* Called within rcu_read_lock(). */
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static bool virtio_should_notify(VirtIODevice *vdev, VirtQueue *vq)
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{
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if (virtio_vdev_has_feature(vdev, VIRTIO_F_RING_PACKED)) {
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return virtio_packed_should_notify(vdev, vq);
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} else {
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return virtio_split_should_notify(vdev, vq);
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}
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}
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void virtio_notify_irqfd(VirtIODevice *vdev, VirtQueue *vq)
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{
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bool should_notify;
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