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

[Jiang Wang <jiang.wang@bytedance.com>]

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[] = {
+		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