From: Jason Wang <jasow...@redhat.com> This patch implements event suppression through device/driver area. Please refer virtio specification for more information.
Signed-off-by: Wei Xu <w...@redhat.com> Signed-off-by: Jason Wang <jasow...@redhat.com> --- hw/virtio/virtio.c | 142 +++++++++++++++++++++++++++++++++++++++++++++++++---- 1 file changed, 133 insertions(+), 9 deletions(-) diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c index 6e7a034d2a..3cf12a62c0 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)); +} + static VRingMemoryRegionCaches *vring_get_region_caches(struct VirtQueue *vq) { VRingMemoryRegionCaches *caches = atomic_rcu_read(&vq->vring.caches); @@ -346,14 +384,8 @@ 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)); @@ -369,6 +401,51 @@ 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; @@ -2290,8 +2367,7 @@ 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; @@ -2314,6 +2390,54 @@ 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; -- 2.16.5