Re: [RFC v2 13/13] vhost: Use VRING_AVAIL_F_NO_INTERRUPT at device call on shadow virtqueue
On Tue, Mar 16, 2021 at 9:08 AM Jason Wang wrote:
>
>
> 在 2021/3/16 上午3:48, Eugenio Pérez 写道:
> > Signed-off-by: Eugenio Pérez
> > ---
> > hw/virtio/vhost-shadow-virtqueue.c | 28 +++-
> > 1 file changed, 27 insertions(+), 1 deletion(-)
> >
> > diff --git a/hw/virtio/vhost-shadow-virtqueue.c
> > b/hw/virtio/vhost-shadow-virtqueue.c
> > index 7df98fc43f..e3879a4622 100644
> > --- a/hw/virtio/vhost-shadow-virtqueue.c
> > +++ b/hw/virtio/vhost-shadow-virtqueue.c
> > @@ -71,10 +71,35 @@ typedef struct VhostShadowVirtqueue {
> > /* Next head to consume from device */
> > uint16_t used_idx;
> >
> > +/* Cache for the exposed notification flag */
> > +bool notification;
> > +
> > /* Descriptors copied from guest */
> > vring_desc_t descs[];
> > } VhostShadowVirtqueue;
> >
> > +static void vhost_shadow_vq_set_notification(VhostShadowVirtqueue *svq,
> > + bool enable)
> > +{
> > +uint16_t notification_flag;
> > +
> > +if (svq->notification == enable) {
> > +return;
> > +}
> > +
> > +notification_flag = virtio_tswap16(svq->vdev,
> > VRING_AVAIL_F_NO_INTERRUPT);
> > +
> > +svq->notification = enable;
> > +if (enable) {
> > +svq->vring.avail->flags &= ~notification_flag;
> > +} else {
> > +svq->vring.avail->flags |= notification_flag;
> > +}
> > +
> > +/* Make sure device reads our flag */
> > +smp_mb();
>
>
> This is a hint, so we don't need memory barrier here.
>
> Thanks
>
I will delete it for the next revision.
Thanks!
>
> > +}
> > +
> > static void vhost_vring_write_descs(VhostShadowVirtqueue *svq,
> > const struct iovec *iovec,
> > size_t num, bool more_descs, bool
> > write)
> > @@ -251,7 +276,7 @@ static void
> > vhost_shadow_vq_handle_call_no_test(EventNotifier *n)
> > do {
> > unsigned i = 0;
> >
> > -/* TODO: Use VRING_AVAIL_F_NO_INTERRUPT */
> > +vhost_shadow_vq_set_notification(svq, false);
> > while (true) {
> > g_autofree VirtQueueElement *elem =
> > vhost_shadow_vq_get_buf(svq);
> > if (!elem) {
> > @@ -269,6 +294,7 @@ static void
> > vhost_shadow_vq_handle_call_no_test(EventNotifier *n)
> > svq->masked_notifier.signaled = true;
> > event_notifier_set(svq->masked_notifier.n);
> > }
> > +vhost_shadow_vq_set_notification(svq, true);
> > } while (vhost_shadow_vq_more_used(svq));
> >
> > if (masked_notifier) {
>
Re: [RFC v2 13/13] vhost: Use VRING_AVAIL_F_NO_INTERRUPT at device call on shadow virtqueue
在 2021/3/16 上午3:48, Eugenio Pérez 写道:
Signed-off-by: Eugenio Pérez
---
hw/virtio/vhost-shadow-virtqueue.c | 28 +++-
1 file changed, 27 insertions(+), 1 deletion(-)
diff --git a/hw/virtio/vhost-shadow-virtqueue.c
b/hw/virtio/vhost-shadow-virtqueue.c
index 7df98fc43f..e3879a4622 100644
--- a/hw/virtio/vhost-shadow-virtqueue.c
+++ b/hw/virtio/vhost-shadow-virtqueue.c
@@ -71,10 +71,35 @@ typedef struct VhostShadowVirtqueue {
/* Next head to consume from device */
uint16_t used_idx;
+/* Cache for the exposed notification flag */
+bool notification;
+
/* Descriptors copied from guest */
vring_desc_t descs[];
} VhostShadowVirtqueue;
+static void vhost_shadow_vq_set_notification(VhostShadowVirtqueue *svq,
+ bool enable)
+{
+uint16_t notification_flag;
+
+if (svq->notification == enable) {
+return;
+}
+
+notification_flag = virtio_tswap16(svq->vdev, VRING_AVAIL_F_NO_INTERRUPT);
+
+svq->notification = enable;
+if (enable) {
+svq->vring.avail->flags &= ~notification_flag;
+} else {
+svq->vring.avail->flags |= notification_flag;
+}
+
+/* Make sure device reads our flag */
+smp_mb();
This is a hint, so we don't need memory barrier here.
Thanks
+}
+
static void vhost_vring_write_descs(VhostShadowVirtqueue *svq,
const struct iovec *iovec,
size_t num, bool more_descs, bool write)
@@ -251,7 +276,7 @@ static void
vhost_shadow_vq_handle_call_no_test(EventNotifier *n)
do {
unsigned i = 0;
-/* TODO: Use VRING_AVAIL_F_NO_INTERRUPT */
+vhost_shadow_vq_set_notification(svq, false);
while (true) {
g_autofree VirtQueueElement *elem = vhost_shadow_vq_get_buf(svq);
if (!elem) {
@@ -269,6 +294,7 @@ static void
vhost_shadow_vq_handle_call_no_test(EventNotifier *n)
svq->masked_notifier.signaled = true;
event_notifier_set(svq->masked_notifier.n);
}
+vhost_shadow_vq_set_notification(svq, true);
} while (vhost_shadow_vq_more_used(svq));
if (masked_notifier) {
[RFC v2 13/13] vhost: Use VRING_AVAIL_F_NO_INTERRUPT at device call on shadow virtqueue
Signed-off-by: Eugenio Pérez
---
hw/virtio/vhost-shadow-virtqueue.c | 28 +++-
1 file changed, 27 insertions(+), 1 deletion(-)
diff --git a/hw/virtio/vhost-shadow-virtqueue.c
b/hw/virtio/vhost-shadow-virtqueue.c
index 7df98fc43f..e3879a4622 100644
--- a/hw/virtio/vhost-shadow-virtqueue.c
+++ b/hw/virtio/vhost-shadow-virtqueue.c
@@ -71,10 +71,35 @@ typedef struct VhostShadowVirtqueue {
/* Next head to consume from device */
uint16_t used_idx;
+/* Cache for the exposed notification flag */
+bool notification;
+
/* Descriptors copied from guest */
vring_desc_t descs[];
} VhostShadowVirtqueue;
+static void vhost_shadow_vq_set_notification(VhostShadowVirtqueue *svq,
+ bool enable)
+{
+uint16_t notification_flag;
+
+if (svq->notification == enable) {
+return;
+}
+
+notification_flag = virtio_tswap16(svq->vdev, VRING_AVAIL_F_NO_INTERRUPT);
+
+svq->notification = enable;
+if (enable) {
+svq->vring.avail->flags &= ~notification_flag;
+} else {
+svq->vring.avail->flags |= notification_flag;
+}
+
+/* Make sure device reads our flag */
+smp_mb();
+}
+
static void vhost_vring_write_descs(VhostShadowVirtqueue *svq,
const struct iovec *iovec,
size_t num, bool more_descs, bool write)
@@ -251,7 +276,7 @@ static void
vhost_shadow_vq_handle_call_no_test(EventNotifier *n)
do {
unsigned i = 0;
-/* TODO: Use VRING_AVAIL_F_NO_INTERRUPT */
+vhost_shadow_vq_set_notification(svq, false);
while (true) {
g_autofree VirtQueueElement *elem = vhost_shadow_vq_get_buf(svq);
if (!elem) {
@@ -269,6 +294,7 @@ static void
vhost_shadow_vq_handle_call_no_test(EventNotifier *n)
svq->masked_notifier.signaled = true;
event_notifier_set(svq->masked_notifier.n);
}
+vhost_shadow_vq_set_notification(svq, true);
} while (vhost_shadow_vq_more_used(svq));
if (masked_notifier) {
--
2.27.0
