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Wed, 16 Jan 2019 18:32:22 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PATCH v2 09/15] virtio: event suppression support for packed ring X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: jasowang@redhat.com, maxime.coquelin@redhat.com, jfreiman@redhat.com, mst@redhat.com Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" From: Wei Xu Signed-off-by: Wei Xu --- hw/virtio/virtio.c | 121 +++++++++++++++++++++++++++++++++++++++++++++++++= ++-- 1 file changed, 118 insertions(+), 3 deletions(-) diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c index 5562ecd..0bcf8a5 100644 --- a/hw/virtio/virtio.c +++ b/hw/virtio/virtio.c @@ -238,6 +238,30 @@ static void vring_desc_read(VirtIODevice *vdev, VRingD= esc *desc, virtio_tswap16s(vdev, &desc->next); } =20 +static void vring_packed_event_read(VirtIODevice *vdev, + MemoryRegionCache *cache, VRingPackedDescEvent= *e) +{ + address_space_read_cached(cache, 0, e, sizeof(*e)); + 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) +{ + virtio_tswap16s(vdev, &off_wrap); + address_space_write_cached(cache, 0, &off_wrap, sizeof(off_wrap)); + address_space_cache_invalidate(cache, 0, sizeof(off_wrap)); +} + +static void vring_packed_flags_write(VirtIODevice *vdev, + MemoryRegionCache *cache, uint16_t flags) +{ + virtio_tswap16s(vdev, &flags); + address_space_write_cached(cache, sizeof(uint16_t), &flags, sizeof(fla= gs)); + address_space_cache_invalidate(cache, sizeof(uint16_t), sizeof(flags)); +} + static VRingMemoryRegionCaches *vring_get_region_caches(struct VirtQueue *= vq) { VRingMemoryRegionCaches *caches =3D atomic_rcu_read(&vq->vring.caches); @@ -344,7 +368,7 @@ static inline void vring_set_avail_event(VirtQueue *vq,= uint16_t val) address_space_cache_invalidate(&caches->used, pa, sizeof(val)); } =20 -void virtio_queue_set_notification(VirtQueue *vq, int enable) +static void virtio_queue_set_notification_split(VirtQueue *vq, int enable) { vq->notification =3D enable; =20 @@ -367,6 +391,51 @@ void virtio_queue_set_notification(VirtQueue *vq, int = enable) rcu_read_unlock(); } =20 +static void virtio_queue_set_notification_packed(VirtQueue *vq, int enable) +{ + VRingPackedDescEvent e; + VRingMemoryRegionCaches *caches; + + rcu_read_lock(); + caches =3D vring_get_region_caches(vq); + vring_packed_event_read(vq->vdev, &caches->used, &e); + + if (!enable) { + e.flags =3D RING_EVENT_FLAGS_DISABLE; + goto out; + } + + e.flags =3D RING_EVENT_FLAGS_ENABLE; + if (virtio_vdev_has_feature(vq->vdev, VIRTIO_RING_F_EVENT_IDX)) { + uint16_t off_wrap =3D vq->shadow_avail_idx | vq->event_wrap_counte= r << 15; + + vring_packed_off_wrap_write(vq->vdev, &caches->used, off_wrap); + /* Make sure off_wrap is wrote before flags */ + smp_wmb(); + + e.flags =3D RING_EVENT_FLAGS_DESC; + } + +out: + vring_packed_flags_write(vq->vdev, &caches->used, e.flags); + rcu_read_unlock(); +} + +void virtio_queue_set_notification(VirtQueue *vq, int enable) +{ + vq->notification =3D enable; + + if (!vq->vring.desc) { + return; + } + + if (virtio_vdev_has_feature(vq->vdev, VIRTIO_F_RING_PACKED)) { + virtio_queue_set_notification_packed(vq, enable); + } else { + virtio_queue_set_notification_split(vq, enable); + } +} + int virtio_queue_ready(VirtQueue *vq) { return vq->vring.avail !=3D 0; @@ -2118,8 +2187,7 @@ static void virtio_set_isr(VirtIODevice *vdev, int va= lue) } } =20 -/* 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; @@ -2142,6 +2210,53 @@ static bool virtio_should_notify(VirtIODevice *vdev,= VirtQueue *vq) return !v || vring_need_event(vring_get_used_event(vq), new, old); } =20 +static bool vring_packed_need_event(VirtQueue *vq, bool wrap, + uint16_t off_wrap, uint16_t new, uint16_t old) +{ + int off =3D off_wrap & ~(1 << 15); + + if (wrap !=3D off_wrap >> 15) { + off -=3D 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 =3D vring_get_region_caches(vq); + vring_packed_event_read(vdev, &caches->avail, &e); + + old =3D vq->signalled_used; + new =3D vq->signalled_used =3D vq->used_idx; + v =3D vq->signalled_used_valid; + vq->signalled_used_valid =3D true; + + if (e.flags =3D=3D RING_EVENT_FLAGS_DISABLE) { + return false; + } else if (e.flags =3D=3D RING_EVENT_FLAGS_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; --=20 1.8.3.1