From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:49232) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gBwnr-00080H-Fs for qemu-devel@nongnu.org; Mon, 15 Oct 2018 02:56:38 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gBwnb-00042F-Nf for qemu-devel@nongnu.org; Mon, 15 Oct 2018 02:56:27 -0400 Received: from mx1.redhat.com ([209.132.183.28]:47130) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1gBwnQ-0003wa-6g for qemu-devel@nongnu.org; Mon, 15 Oct 2018 02:56:10 -0400 References: <1539266915-15216-1-git-send-email-wexu@redhat.com> <1539266915-15216-9-git-send-email-wexu@redhat.com> From: Jason Wang Message-ID: <4547298e-c84d-c244-3f38-a74bf01dd85d@redhat.com> Date: Mon, 15 Oct 2018 14:55:49 +0800 MIME-Version: 1.0 In-Reply-To: <1539266915-15216-9-git-send-email-wexu@redhat.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US 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: wexu@redhat.com, qemu-devel@nongnu.org Cc: tiwei.bie@intel.com, jfreimann@redhat.com, maxime.coquelin@redhat.com 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, VR= ingDesc *desc, > virtio_tswap16s(vdev, &desc->next); > } > =20 > +static void vring_packed_event_read(VirtIODevice *vdev, > + MemoryRegionCache *cache, VRingPackedDescE= vent *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_wra= p) > +{ > + 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= (flags)); > + address_space_cache_invalidate(cache, sizeof(uint16_t), sizeof(fla= gs)); > +} > + > static VRingMemoryRegionCaches *vring_get_region_caches(struct VirtQu= eue *vq) > { > VRingMemoryRegionCaches *caches =3D atomic_rcu_read(&vq->vring.ca= ches); > @@ -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)); > } > =20 > -void virtio_queue_set_notification(VirtQueue *vq, int enable) > +static void virtio_queue_set_notification_split(VirtQueue *vq, int ena= ble) > { > vq->notification =3D enable; > =20 > @@ -370,6 +394,51 @@ void virtio_queue_set_notification(VirtQueue *vq, = int enable) > rcu_read_unlock(); > } > =20 > +static void virtio_queue_set_notification_packed(VirtQueue *vq, int en= able) > +{ > + 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; > + > + vring_packed_off_wrap_write(vq->vdev, &caches->device, off_wra= p); > + /* 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, in= t value) > } > } > =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; > @@ -2127,6 +2195,58 @@ static bool virtio_should_notify(VirtIODevice *v= dev, VirtQueue *vq) > return !v || vring_need_event(vring_get_used_event(vq), new, old)= ; > } > =20 > +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; > + } Let's use a more compact and verified version from dpdk: static bool vhost_vring_packed_need_event(struct vhost_virtqueue *vq, =C2=A0=C2=A0=C2=A0 =C2=A0=C2=A0=C2=A0 =C2=A0=C2=A0=C2=A0 =C2=A0=C2=A0=C2= =A0 =C2=A0=C2=A0=C2=A0 =C2=A0 bool wrap, __u16 off_wrap, __u16 new, =C2=A0=C2=A0=C2=A0 =C2=A0=C2=A0=C2=A0 =C2=A0=C2=A0=C2=A0 =C2=A0=C2=A0=C2= =A0 =C2=A0=C2=A0=C2=A0 =C2=A0 __u16 old) { =C2=A0=C2=A0=C2=A0 int off =3D off_wrap & ~(1 << 15); =C2=A0=C2=A0=C2=A0 if (wrap !=3D off_wrap >> 15) =C2=A0=C2=A0=C2=A0 =C2=A0=C2=A0=C2=A0 off -=3D vq->num; =C2=A0=C2=A0=C2=A0 return vring_need_event(off, new, old); } Thanks > + > + 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;