Re: [RFC v1 1/6] virtio/vsock: add VIRTIO_VSOCK_F_DGRAM feature bit

[Stefano Garzarella <sgarzare@redhat.com>]

On Wed, Jun 09, 2021 at 11:24:53PM +0000, Jiang Wang wrote:
>When this feature is enabled, allocate 5 queues,
>otherwise, allocate 3 queues to be compatible with
>old QEMU versions.
>
>Signed-off-by: Jiang Wang <jiang.wang@bytedance.com>
>---
> drivers/vhost/vsock.c             |  3 +-
> include/linux/virtio_vsock.h      |  9 +++++
> include/uapi/linux/virtio_vsock.h |  3 ++
> net/vmw_vsock/virtio_transport.c  | 73 +++++++++++++++++++++++++++++++++++----
> 4 files changed, 80 insertions(+), 8 deletions(-)
>
>diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
>index 5e78fb719602..81d064601093 100644
>--- a/drivers/vhost/vsock.c
>+++ b/drivers/vhost/vsock.c
>@@ -31,7 +31,8 @@
>
> enum {
> 	VHOST_VSOCK_FEATURES = VHOST_FEATURES |
>-			       (1ULL << VIRTIO_F_ACCESS_PLATFORM)
>+			       (1ULL << VIRTIO_F_ACCESS_PLATFORM) |
>+			       (1ULL << VIRTIO_VSOCK_F_DGRAM)
> };
>
> enum {
>diff --git a/include/linux/virtio_vsock.h b/include/linux/virtio_vsock.h
>index dc636b727179..ba3189ed9345 100644
>--- a/include/linux/virtio_vsock.h
>+++ b/include/linux/virtio_vsock.h
>@@ -18,6 +18,15 @@ enum {
> 	VSOCK_VQ_MAX    = 3,
> };
>
>+enum {
>+	VSOCK_VQ_STREAM_RX     = 0, /* for host to guest data */
>+	VSOCK_VQ_STREAM_TX     = 1, /* for guest to host data */
>+	VSOCK_VQ_DGRAM_RX       = 2,
>+	VSOCK_VQ_DGRAM_TX       = 3,
>+	VSOCK_VQ_EX_EVENT       = 4,
>+	VSOCK_VQ_EX_MAX         = 5,
>+};
>+
> /* Per-socket state (accessed via vsk->trans) */
> struct virtio_vsock_sock {
> 	struct vsock_sock *vsk;
>diff --git a/include/uapi/linux/virtio_vsock.h b/include/uapi/linux/virtio_vsock.h
>index 1d57ed3d84d2..b56614dff1c9 100644
>--- a/include/uapi/linux/virtio_vsock.h
>+++ b/include/uapi/linux/virtio_vsock.h
>@@ -38,6 +38,9 @@
> #include <linux/virtio_ids.h>
> #include <linux/virtio_config.h>
>
>+/* The feature bitmap for virtio net */
>+#define VIRTIO_VSOCK_F_DGRAM	0	/* Host support dgram vsock */
>+
> struct virtio_vsock_config {
> 	__le64 guest_cid;
> } __attribute__((packed));
>diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c
>index 2700a63ab095..7dcb8db23305 100644
>--- a/net/vmw_vsock/virtio_transport.c
>+++ b/net/vmw_vsock/virtio_transport.c
>@@ -27,7 +27,8 @@ static DEFINE_MUTEX(the_virtio_vsock_mutex); /* protects the_virtio_vsock */
>
> struct virtio_vsock {
> 	struct virtio_device *vdev;
>-	struct virtqueue *vqs[VSOCK_VQ_MAX];
>+	struct virtqueue **vqs;
>+	bool has_dgram;
>
> 	/* Virtqueue processing is deferred to a workqueue */
> 	struct work_struct tx_work;
>@@ -333,7 +334,10 @@ static int virtio_vsock_event_fill_one(struct virtio_vsock *vsock,
> 	struct scatterlist sg;
> 	struct virtqueue *vq;
>
>-	vq = vsock->vqs[VSOCK_VQ_EVENT];
>+	if (vsock->has_dgram)
>+		vq = vsock->vqs[VSOCK_VQ_EX_EVENT];
>+	else
>+		vq = vsock->vqs[VSOCK_VQ_EVENT];
>
> 	sg_init_one(&sg, event, sizeof(*event));
>
>@@ -351,7 +355,10 @@ static void virtio_vsock_event_fill(struct virtio_vsock *vsock)
> 		virtio_vsock_event_fill_one(vsock, event);
> 	}
>
>-	virtqueue_kick(vsock->vqs[VSOCK_VQ_EVENT]);
>+	if (vsock->has_dgram)
>+		virtqueue_kick(vsock->vqs[VSOCK_VQ_EX_EVENT]);
>+	else
>+		virtqueue_kick(vsock->vqs[VSOCK_VQ_EVENT]);
> }
>
> static void virtio_vsock_reset_sock(struct sock *sk)
>@@ -391,7 +398,10 @@ static void virtio_transport_event_work(struct work_struct *work)
> 		container_of(work, struct virtio_vsock, event_work);
> 	struct virtqueue *vq;
>
>-	vq = vsock->vqs[VSOCK_VQ_EVENT];
>+	if (vsock->has_dgram)
>+		vq = vsock->vqs[VSOCK_VQ_EX_EVENT];
>+	else
>+		vq = vsock->vqs[VSOCK_VQ_EVENT];
>
> 	mutex_lock(&vsock->event_lock);
>
>@@ -411,7 +421,10 @@ static void virtio_transport_event_work(struct work_struct *work)
> 		}
> 	} while (!virtqueue_enable_cb(vq));
>
>-	virtqueue_kick(vsock->vqs[VSOCK_VQ_EVENT]);
>+	if (vsock->has_dgram)
>+		virtqueue_kick(vsock->vqs[VSOCK_VQ_EX_EVENT]);
>+	else
>+		virtqueue_kick(vsock->vqs[VSOCK_VQ_EVENT]);
> out:
> 	mutex_unlock(&vsock->event_lock);
> }
>@@ -434,6 +447,10 @@ static void virtio_vsock_tx_done(struct virtqueue *vq)
> 	queue_work(virtio_vsock_workqueue, &vsock->tx_work);
> }
>
>+static void virtio_vsock_dgram_tx_done(struct virtqueue *vq)
>+{
>+}
>+
> static void virtio_vsock_rx_done(struct virtqueue *vq)
> {
> 	struct virtio_vsock *vsock = vq->vdev->priv;
>@@ -443,6 +460,10 @@ static void virtio_vsock_rx_done(struct virtqueue *vq)
> 	queue_work(virtio_vsock_workqueue, &vsock->rx_work);
> }
>
>+static void virtio_vsock_dgram_rx_done(struct virtqueue *vq)
>+{
>+}
>+
> static struct virtio_transport virtio_transport = {
> 	.transport = {
> 		.module                   = THIS_MODULE,
>@@ -545,13 +566,29 @@ static int virtio_vsock_probe(struct virtio_device *vdev)
> 		virtio_vsock_tx_done,
> 		virtio_vsock_event_done,
> 	};
>+	vq_callback_t *ex_callbacks[] = {

'ex' is not clear, maybe better 'dgram'?

What happen if F_DGRAM is negotiated, but not F_STREAM?

>+		virtio_vsock_rx_done,
>+		virtio_vsock_tx_done,
>+		virtio_vsock_dgram_rx_done,
>+		virtio_vsock_dgram_tx_done,
>+		virtio_vsock_event_done,
>+	};
>+
> 	static const char * const names[] = {
> 		"rx",
> 		"tx",
> 		"event",
> 	};
>+	static const char * const ex_names[] = {
>+		"rx",
>+		"tx",
>+		"dgram_rx",
>+		"dgram_tx",
>+		"event",
>+	};
>+
> 	struct virtio_vsock *vsock = NULL;
>-	int ret;
>+	int ret, max_vq;
>
> 	ret = mutex_lock_interruptible(&the_virtio_vsock_mutex);
> 	if (ret)
>@@ -572,9 +609,30 @@ static int virtio_vsock_probe(struct virtio_device *vdev)
>
> 	vsock->vdev = vdev;
>
>-	ret = virtio_find_vqs(vsock->vdev, VSOCK_VQ_MAX,
>+	if (virtio_has_feature(vdev, VIRTIO_VSOCK_F_DGRAM))
>+		vsock->has_dgram = true;
>+
>+	if (vsock->has_dgram)
>+		max_vq = VSOCK_VQ_EX_MAX;
>+	else
>+		max_vq = VSOCK_VQ_MAX;
>+
>+	vsock->vqs = kmalloc_array(max_vq, sizeof(struct virtqueue *), GFP_KERNEL);
>+	if (!vsock->vqs) {
>+		ret = -ENOMEM;
>+		goto out;
>+	}
>+
>+	if (vsock->has_dgram) {
>+		ret = virtio_find_vqs(vsock->vdev, max_vq,
>+			      vsock->vqs, ex_callbacks, ex_names,
>+			      NULL);
>+	} else {
>+		ret = virtio_find_vqs(vsock->vdev, max_vq,
> 			      vsock->vqs, callbacks, names,
> 			      NULL);
>+	}
>+
> 	if (ret < 0)
> 		goto out;
>
>@@ -695,6 +753,7 @@ static struct virtio_device_id id_table[] = {
> };
>
> static unsigned int features[] = {
>+	VIRTIO_VSOCK_F_DGRAM,
> };
>
> static struct virtio_driver virtio_vsock_driver = {
>-- 
>2.11.0
>