From: "Michael S. Tsirkin" <mst@redhat.com>
To: Keiichi Watanabe <keiichiw@chromium.org>
Cc: chirantan@chromium.org, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org,
virtualization@lists.linux-foundation.org,
"David S . Miller" <davem@davemloft.net>
Subject: Re: [PATCH] virtio_net: Enable MSI-X vector for ctrl queue
Date: Fri, 18 Jun 2021 08:38:10 -0400 [thread overview]
Message-ID: <20210618083650-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <20210618072625.957837-1-keiichiw@chromium.org>
On Fri, Jun 18, 2021 at 04:26:25PM +0900, Keiichi Watanabe wrote:
> When we use vhost-user backend on the host, MSI-X vector should be set
> so that the vmm can get an irq FD and send it to the backend device
> process with vhost-user protocol.
> Since whether the vector is set for a queue is determined depending on
> the queue has a callback, this commit sets an empty callback for
> virtio-net's control queue.
>
> Signed-off-by: Keiichi Watanabe <keiichiw@chromium.org>
I'm confused by this explanation. If the vmm wants to get
an interrupt it can do so - why change the guest driver?
> ---
> drivers/net/virtio_net.c | 7 ++++++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 11f722460513..002e3695d4b3 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -2696,6 +2696,11 @@ static void virtnet_del_vqs(struct virtnet_info *vi)
> virtnet_free_queues(vi);
> }
>
> +static void virtnet_ctrlq_done(struct virtqueue *rvq)
> +{
> + /* Do nothing */
> +}
> +
> /* How large should a single buffer be so a queue full of these can fit at
> * least one full packet?
> * Logic below assumes the mergeable buffer header is used.
> @@ -2748,7 +2753,7 @@ static int virtnet_find_vqs(struct virtnet_info *vi)
>
> /* Parameters for control virtqueue, if any */
> if (vi->has_cvq) {
> - callbacks[total_vqs - 1] = NULL;
> + callbacks[total_vqs - 1] = virtnet_ctrlq_done;
> names[total_vqs - 1] = "control";
> }
>
> --
> 2.32.0.288.g62a8d224e6-goog
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WARNING: multiple messages have this Message-ID (diff)
From: "Michael S. Tsirkin" <mst@redhat.com>
To: Keiichi Watanabe <keiichiw@chromium.org>
Cc: netdev@vger.kernel.org, chirantan@chromium.org,
Jason Wang <jasowang@redhat.com>,
"David S . Miller" <davem@davemloft.net>,
virtualization@lists.linux-foundation.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] virtio_net: Enable MSI-X vector for ctrl queue
Date: Fri, 18 Jun 2021 08:38:10 -0400 [thread overview]
Message-ID: <20210618083650-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <20210618072625.957837-1-keiichiw@chromium.org>
On Fri, Jun 18, 2021 at 04:26:25PM +0900, Keiichi Watanabe wrote:
> When we use vhost-user backend on the host, MSI-X vector should be set
> so that the vmm can get an irq FD and send it to the backend device
> process with vhost-user protocol.
> Since whether the vector is set for a queue is determined depending on
> the queue has a callback, this commit sets an empty callback for
> virtio-net's control queue.
>
> Signed-off-by: Keiichi Watanabe <keiichiw@chromium.org>
I'm confused by this explanation. If the vmm wants to get
an interrupt it can do so - why change the guest driver?
> ---
> drivers/net/virtio_net.c | 7 ++++++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 11f722460513..002e3695d4b3 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -2696,6 +2696,11 @@ static void virtnet_del_vqs(struct virtnet_info *vi)
> virtnet_free_queues(vi);
> }
>
> +static void virtnet_ctrlq_done(struct virtqueue *rvq)
> +{
> + /* Do nothing */
> +}
> +
> /* How large should a single buffer be so a queue full of these can fit at
> * least one full packet?
> * Logic below assumes the mergeable buffer header is used.
> @@ -2748,7 +2753,7 @@ static int virtnet_find_vqs(struct virtnet_info *vi)
>
> /* Parameters for control virtqueue, if any */
> if (vi->has_cvq) {
> - callbacks[total_vqs - 1] = NULL;
> + callbacks[total_vqs - 1] = virtnet_ctrlq_done;
> names[total_vqs - 1] = "control";
> }
>
> --
> 2.32.0.288.g62a8d224e6-goog
next prev parent reply other threads:[~2021-06-18 12:38 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-18 7:26 [PATCH] virtio_net: Enable MSI-X vector for ctrl queue Keiichi Watanabe
2021-06-18 12:38 ` Michael S. Tsirkin [this message]
2021-06-18 12:38 ` Michael S. Tsirkin
2021-06-21 6:21 ` Jason Wang
2021-06-21 6:21 ` Jason Wang
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