Re: [PATCH RFC net-next v2 2/4] virtio/vsock: add VIRTIO_VSOCK_F_DGRAM feature bit

From: Stefano Garzarella <sgarzare@redhat.com>
To: Bobby Eshleman <bobby.eshleman@bytedance.com>
Cc: Vishnu Dasa <vdasa@vmware.com>, Wei Liu <wei.liu@kernel.org>,
	Jiang Wang <jiang.wang@bytedance.com>,
	kvm@vger.kernel.org, "Michael S. Tsirkin" <mst@redhat.com>,
	VMware PV-Drivers Reviewers <pv-drivers@vmware.com>,
	Dexuan Cui <decui@microsoft.com>,
	Haiyang Zhang <haiyangz@microsoft.com>,
	linux-kernel@vger.kernel.org,
	virtualization@lists.linux-foundation.org,
	Bryan Tan <bryantan@vmware.com>,
	Eric Dumazet <edumazet@google.com>,
	linux-hyperv@vger.kernel.org,
	Stefan Hajnoczi <stefanha@redhat.com>,
	netdev@vger.kernel.org, Jakub Kicinski <kuba@kernel.org>,
	Paolo Abeni <pabeni@redhat.com>,
	"David S. Miller" <davem@davemloft.net>
Subject: Re: [PATCH RFC net-next v2 2/4] virtio/vsock: add VIRTIO_VSOCK_F_DGRAM feature bit
Date: Wed, 19 Apr 2023 11:30:21 +0200	[thread overview]
Message-ID: <nbuuohh72i4n27rzlg7sj7bwsrsrnnxxcxj6w5yotw5bhpcznt@ormwl5d6jiuw> (raw)
In-Reply-To: <20230413-b4-vsock-dgram-v2-2-079cc7cee62e@bytedance.com>

On Fri, Apr 14, 2023 at 12:25:58AM +0000, Bobby Eshleman wrote:
>This commit adds a feature bit for virtio vsock to support datagrams.
>This commit should not be applied without first applying the commit
>that implements datagrams for virtio.
>
>Signed-off-by: Jiang Wang <jiang.wang@bytedance.com>
>Signed-off-by: Bobby Eshleman <bobby.eshleman@bytedance.com>
>---
> drivers/vhost/vsock.c             | 3 ++-
> include/uapi/linux/virtio_vsock.h | 1 +
> net/vmw_vsock/virtio_transport.c  | 8 ++++++--
> 3 files changed, 9 insertions(+), 3 deletions(-)
>
>diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
>index dff6ee1c479b..028cf079225e 100644
>--- a/drivers/vhost/vsock.c
>+++ b/drivers/vhost/vsock.c
>@@ -32,7 +32,8 @@
> enum {
> 	VHOST_VSOCK_FEATURES = VHOST_FEATURES |
> 			       (1ULL << VIRTIO_F_ACCESS_PLATFORM) |
>-			       (1ULL << VIRTIO_VSOCK_F_SEQPACKET)
>+			       (1ULL << VIRTIO_VSOCK_F_SEQPACKET) |
>+			       (1ULL << VIRTIO_VSOCK_F_DGRAM)
> };
>
> enum {
>diff --git a/include/uapi/linux/virtio_vsock.h b/include/uapi/linux/virtio_vsock.h
>index 331be28b1d30..0975b9c88292 100644
>--- a/include/uapi/linux/virtio_vsock.h
>+++ b/include/uapi/linux/virtio_vsock.h
>@@ -40,6 +40,7 @@
>
> /* The feature bitmap for virtio vsock */
> #define VIRTIO_VSOCK_F_SEQPACKET	1	/* SOCK_SEQPACKET supported */
>+#define VIRTIO_VSOCK_F_DGRAM		2	/* Host support dgram vsock */
>
> struct virtio_vsock_config {
> 	__le64 guest_cid;
>diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c
>index 582c6c0f788f..bb43eea9a6f9 100644
>--- a/net/vmw_vsock/virtio_transport.c
>+++ b/net/vmw_vsock/virtio_transport.c
>@@ -29,6 +29,7 @@ static struct virtio_transport virtio_transport; /* forward declaration */
> struct virtio_vsock {
> 	struct virtio_device *vdev;
> 	struct virtqueue *vqs[VSOCK_VQ_MAX];
>+	bool has_dgram;
>
> 	/* Virtqueue processing is deferred to a workqueue */
> 	struct work_struct tx_work;
>@@ -640,7 +641,6 @@ static int virtio_vsock_probe(struct virtio_device *vdev)
> 	}
>
> 	vsock->vdev = vdev;
>-
> 	vsock->rx_buf_nr = 0;
> 	vsock->rx_buf_max_nr = 0;
> 	atomic_set(&vsock->queued_replies, 0);
>@@ -657,6 +657,9 @@ static int virtio_vsock_probe(struct virtio_device *vdev)
> 	if (virtio_has_feature(vdev, VIRTIO_VSOCK_F_SEQPACKET))
> 		vsock->seqpacket_allow = true;
>
>+	if (virtio_has_feature(vdev, VIRTIO_VSOCK_F_DGRAM))
>+		vsock->has_dgram = true;

This is unused for now, but I think the idea is to use in
virtio_transport_dgram_allow(), right?

I would follow `seqpacket_allow` in this case.

Thanks,
Stefano

>+
> 	vdev->priv = vsock;
>
> 	ret = virtio_vsock_vqs_init(vsock);
>@@ -749,7 +752,8 @@ static struct virtio_device_id id_table[] = {
> };
>
> static unsigned int features[] = {
>-	VIRTIO_VSOCK_F_SEQPACKET
>+	VIRTIO_VSOCK_F_SEQPACKET,
>+	VIRTIO_VSOCK_F_DGRAM
> };
>
> static struct virtio_driver virtio_vsock_driver = {
>
>-- 
>2.30.2
>

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