From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:39606) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gBy7r-0006wQ-1G for qemu-devel@nongnu.org; Mon, 15 Oct 2018 04:21:19 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gBy7k-00085t-F0 for qemu-devel@nongnu.org; Mon, 15 Oct 2018 04:21:18 -0400 Received: from mx1.redhat.com ([209.132.183.28]:51460) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1gBy7k-00085X-6f for qemu-devel@nongnu.org; Mon, 15 Oct 2018 04:21:12 -0400 Date: Mon, 15 Oct 2018 16:20:50 +0800 From: Wei Xu Message-ID: <20181015082050.GG27871@wei-ubt> References: <1539266915-15216-1-git-send-email-wexu@redhat.com> <1539266915-15216-9-git-send-email-wexu@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [[RFC v3 08/12] virtio: event suppression support for packed ring List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Jason Wang Cc: qemu-devel@nongnu.org, tiwei.bie@intel.com, jfreimann@redhat.com, maxime.coquelin@redhat.com On Mon, Oct 15, 2018 at 02:59:48PM +0800, Jason Wang wrote: >=20 >=20 > On 2018=E5=B9=B410=E6=9C=8811=E6=97=A5 22:08, wexu@redhat.com wrote: > >From: Wei Xu > > > >Signed-off-by: Wei Xu > >--- > > hw/virtio/virtio.c | 126 +++++++++++++++++++++++++++++++++++++++++++= ++++++++-- > > 1 file changed, 123 insertions(+), 3 deletions(-) > > > >diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c > >index d12a7e3..1d25776 100644 > >--- a/hw/virtio/virtio.c > >+++ b/hw/virtio/virtio.c > >@@ -241,6 +241,30 @@ static void vring_desc_read(VirtIODevice *vdev, V= RingDesc *desc, > > virtio_tswap16s(vdev, &desc->next); > > } > >+static void vring_packed_event_read(VirtIODevice *vdev, > >+ MemoryRegionCache *cache, VRingPackedDesc= Event *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_wr= ap) > >+{ > >+ 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, sizeo= f(flags)); > >+ address_space_cache_invalidate(cache, sizeof(uint16_t), sizeof(fl= ags)); > >+} > >+ > > static VRingMemoryRegionCaches *vring_get_region_caches(struct VirtQ= ueue *vq) > > { > > VRingMemoryRegionCaches *caches =3D atomic_rcu_read(&vq->vring.c= aches); > >@@ -347,7 +371,7 @@ 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_set_notification_split(VirtQueue *vq, int en= able) > > { > > vq->notification =3D enable; > >@@ -370,6 +394,51 @@ void virtio_queue_set_notification(VirtQueue *vq,= int enable) > > rcu_read_unlock(); > > } > >+static void virtio_queue_set_notification_packed(VirtQueue *vq, int e= nable) > >+{ > >+ VRingPackedDescEvent e; > >+ VRingMemoryRegionCaches *caches; > >+ > >+ rcu_read_lock(); > >+ caches =3D vring_get_region_caches(vq); > >+ vring_packed_event_read(vq->vdev, &caches->device, &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->event_idx | vq->event_wrap_counter = << 15; >=20 > Btw, why not just use shadow_avail_idx here? It is nice to do that but an issue here is that it is 'shadow_avail_idx' = for Rx but 'used_idx' for Tx when setting up for a kick, haven't figured out = a clear fix because it helps easier migration part work, any idea? Wei >=20 > Thanks >=20 > >+ > >+ vring_packed_off_wrap_write(vq->vdev, &caches->device, off_wr= ap); > >+ /* 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->device, 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; > >@@ -2103,8 +2172,7 @@ static void virtio_set_isr(VirtIODevice *vdev, i= nt 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; > >@@ -2127,6 +2195,58 @@ 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, uint16_t off_wrap, > >+ uint16_t new, uint16_t old) > >+{ > >+ bool wrap =3D vq->event_wrap_counter; > >+ int off =3D off_wrap & ~(1 << 15); > >+ > >+ if (new < old) { > >+ new +=3D vq->vring.num; > >+ wrap ^=3D 1; > >+ } > >+ > >+ 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->driver, &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, 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