Re: [RFC PATCH v4 17/20] vhost: Use VRING_AVAIL_F_NO_INTERRUPT at device call on shadow virtqueue

[Jason Wang]

在 2021/10/1 下午3:06, Eugenio Pérez 写道:
> Signed-off-by: Eugenio Pérez <eperezma@redhat.com>


Commit log please.

Thanks


> ---
>   hw/virtio/vhost-shadow-virtqueue.c | 24 +++++++++++++++++++++++-
>   1 file changed, 23 insertions(+), 1 deletion(-)
>
> diff --git a/hw/virtio/vhost-shadow-virtqueue.c 
> b/hw/virtio/vhost-shadow-virtqueue.c
> index 775f8d36a0..2fd0bab75d 100644
> --- a/hw/virtio/vhost-shadow-virtqueue.c
> +++ b/hw/virtio/vhost-shadow-virtqueue.c
> @@ -60,6 +60,9 @@ typedef struct VhostShadowVirtqueue {
>   
>       /* Next head to consume from device */
>       uint16_t used_idx;
> +
> +    /* Cache for the exposed notification flag */
> +    bool notification;
>   } VhostShadowVirtqueue;
>   
>   /* If the device is using some of these, SVQ cannot communicate */
> @@ -105,6 +108,24 @@ bool vhost_svq_valid_device_features(uint64_t 
> *dev_features)
>       return r;
>   }
>   
> +static void vhost_svq_set_notification(VhostShadowVirtqueue *svq, bool enable)
> +{
> +    uint16_t notification_flag;
> +
> +    if (svq->notification == enable) {
> +        return;
> +    }
> +
> +    notification_flag = cpu_to_le16(VRING_AVAIL_F_NO_INTERRUPT);
> +
> +    svq->notification = enable;
> +    if (enable) {
> +        svq->vring.avail->flags &= ~notification_flag;
> +    } else {
> +        svq->vring.avail->flags |= notification_flag;
> +    }
> +}
> +
>   static void vhost_vring_write_descs(VhostShadowVirtqueue *svq,
>                                       const struct iovec *iovec,
>                                       size_t num, bool more_descs, bool write)
> @@ -273,7 +294,7 @@ static void vhost_svq_handle_call_no_test(EventNotifier *n)
>       do {
>           unsigned i = 0;
>   
> -        /* TODO: Use VRING_AVAIL_F_NO_INTERRUPT */
> +        vhost_svq_set_notification(svq, false);
>           while (true) {
>               g_autofree VirtQueueElement *elem = vhost_svq_get_buf(svq);
>               if (!elem) {
> @@ -286,6 +307,7 @@ static void vhost_svq_handle_call_no_test(EventNotifier *n)
>   
>           virtqueue_flush(vq, i);
>           event_notifier_set(&svq->guest_call_notifier);
> +        vhost_svq_set_notification(svq, true);
>       } while (vhost_svq_more_used(svq));
>   }
>