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

On Fri, Jun 18, 2021 at 2:40 AM Stefano Garzarella [off-list ref] wrote:

On Wed, Jun 09, 2021 at 11:24:53PM +0000, Jiang Wang wrote:

quoted

When this feature is enabled, allocate 5 queues,
otherwise, allocate 3 queues to be compatible with
old QEMU versions.

Signed-off-by: Jiang Wang <redacted>
---
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'?

sure.

What happen if F_DGRAM is negotiated, but not F_STREAM?

Hmm. In my mind, F_STREAM is always negotiated. Do we want to add
support when F_STREAM is not negotiated?

quoted

+              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