Jason Wang
2021-Mar-01 06:24 UTC
[RFC v2 7/7] vhost: Route host->guest notification through shadow virtqueue
On 2021/2/9 11:37 ??, Eugenio P?rez wrote:> Signed-off-by: Eugenio P?rez <eperezma at redhat.com> > --- > hw/virtio/vhost-shadow-virtqueue.h | 2 ++ > hw/virtio/vhost-shadow-virtqueue.c | 49 ++++++++++++++++++++++++++++++ > hw/virtio/vhost.c | 5 ++- > 3 files changed, 55 insertions(+), 1 deletion(-) > > diff --git a/hw/virtio/vhost-shadow-virtqueue.h b/hw/virtio/vhost-shadow-virtqueue.h > index c45035c4b7..210133434c 100644 > --- a/hw/virtio/vhost-shadow-virtqueue.h > +++ b/hw/virtio/vhost-shadow-virtqueue.h > @@ -17,6 +17,8 @@ > > typedef struct VhostShadowVirtqueue VhostShadowVirtqueue; > > +EventNotifier *vhost_shadow_vq_get_call_notifier(VhostShadowVirtqueue *vq); > + > bool vhost_shadow_vq_start_rcu(struct vhost_dev *dev, > unsigned idx, > VhostShadowVirtqueue *svq); > diff --git a/hw/virtio/vhost-shadow-virtqueue.c b/hw/virtio/vhost-shadow-virtqueue.c > index 01f282d434..61d98ae652 100644 > --- a/hw/virtio/vhost-shadow-virtqueue.c > +++ b/hw/virtio/vhost-shadow-virtqueue.c > @@ -24,6 +24,8 @@ typedef struct VhostShadowVirtqueue { > > /* Borrowed virtqueue's guest to host notifier. */ > EventNotifier host_notifier; > + /* Host to guest notifier */ > + EventNotifier *guest_notifier; > > /* Virtio queue shadowing */ > VirtQueue *vq; > @@ -40,6 +42,26 @@ static void vhost_handle_guest_kick(EventNotifier *n) > } > } > > +/* Forward vhost notifications */ > +static void vhost_handle_call(EventNotifier *n) > +{ > + VhostShadowVirtqueue *svq = container_of(n, VhostShadowVirtqueue, > + call_notifier); > + > + if (event_notifier_test_and_clear(n)) { > + event_notifier_set(svq->guest_notifier); > + } > +}So I wonder how this is synchonized with virtqueue mask/unmask. Or the masking is totally transparent to shadow virtqueue? Thanks> + > +/* > + * Get the vhost call notifier of the shadow vq > + * @vq Shadow virtqueue > + */ > +EventNotifier *vhost_shadow_vq_get_call_notifier(VhostShadowVirtqueue *vq) > +{ > + return &vq->call_notifier; > +} > + > /* > * Start shadow virtqueue operation. > * @dev vhost device > @@ -57,6 +79,10 @@ bool vhost_shadow_vq_start_rcu(struct vhost_dev *dev, > .index = idx, > .fd = event_notifier_get_fd(&svq->kick_notifier), > }; > + struct vhost_vring_file call_file = { > + .index = idx, > + .fd = event_notifier_get_fd(&svq->call_notifier), > + }; > int r; > > /* Check that notifications are still going directly to vhost dev */ > @@ -66,6 +92,7 @@ bool vhost_shadow_vq_start_rcu(struct vhost_dev *dev, > event_notifier_get_fd(vq_host_notifier)); > event_notifier_set_handler(&svq->host_notifier, vhost_handle_guest_kick); > > + svq->guest_notifier = virtio_queue_get_guest_notifier(svq->vq); > r = dev->vhost_ops->vhost_set_vring_kick(dev, &kick_file); > if (unlikely(r != 0)) { > error_report("Couldn't set kick fd: %s", strerror(errno)); > @@ -75,8 +102,19 @@ bool vhost_shadow_vq_start_rcu(struct vhost_dev *dev, > /* Check for pending notifications from the guest */ > vhost_handle_guest_kick(&svq->host_notifier); > > + r = dev->vhost_ops->vhost_set_vring_call(dev, &call_file); > + if (r != 0) { > + error_report("Couldn't set call fd: %s", strerror(errno)); > + goto err_set_vring_call; > + } > + > return true; > > +err_set_vring_call: > + kick_file.fd = event_notifier_get_fd(vq_host_notifier); > + r = dev->vhost_ops->vhost_set_vring_kick(dev, &kick_file); > + assert(r == 0); > + > err_set_vring_kick: > event_notifier_set_handler(&svq->host_notifier, NULL); > > @@ -108,6 +146,16 @@ void vhost_shadow_vq_stop_rcu(struct vhost_dev *dev, > assert(r == 0); > > event_notifier_set_handler(&svq->host_notifier, NULL); > + > + if (!dev->vqs[idx].notifier_is_masked) { > + EventNotifier *e = vhost_shadow_vq_get_call_notifier(svq); > + > + /* Restore vhost call */ > + vhost_virtqueue_mask(dev, dev->vdev, dev->vq_index + idx, false); > + > + /* Check for pending calls */ > + vhost_handle_call(e); > + } > } > > /* > @@ -136,6 +184,7 @@ VhostShadowVirtqueue *vhost_shadow_vq_new(struct vhost_dev *dev, int idx) > goto err_init_call_notifier; > } > > + event_notifier_set_handler(&svq->call_notifier, vhost_handle_call); > return g_steal_pointer(&svq); > > err_init_call_notifier: > diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c > index 9d4728e545..0dc95679e9 100644 > --- a/hw/virtio/vhost.c > +++ b/hw/virtio/vhost.c > @@ -975,7 +975,6 @@ static int vhost_sw_live_migration_start(struct vhost_dev *dev) > for (idx = 0; idx < dev->nvqs; ++idx) { > bool ok = vhost_shadow_vq_start_rcu(dev, idx, > dev->shadow_vqs[idx]); > - > if (!ok) { > int stop_idx = idx; > > @@ -1608,6 +1607,10 @@ void vhost_virtqueue_mask(struct vhost_dev *hdev, VirtIODevice *vdev, int n, > if (mask) { > assert(vdev->use_guest_notifier_mask); > file.fd = event_notifier_get_fd(&hdev->vqs[index].masked_notifier); > + } else if (hdev->sw_lm_enabled) { > + VhostShadowVirtqueue *svq = hdev->shadow_vqs[n]; > + EventNotifier *e = vhost_shadow_vq_get_call_notifier(svq); > + file.fd = event_notifier_get_fd(e); > } else { > file.fd = event_notifier_get_fd(virtio_queue_get_guest_notifier(vvq)); > }