Hi Jason,

On 12/13/23 05:52, Jason Wang wrote:

On Tue, Dec 12, 2023 at 9:17 PM Maxime Coquelin
[off-list ref] wrote:

quoted

Virtio-net driver control queue implementation is not safe
when used with VDUSE. If the VDUSE application does not
reply to control queue messages, it currently ends up
hanging the kernel thread sending this command.

Some work is on-going to make the control queue
implementation robust with VDUSE. Until it is completed,
let's disable control virtqueue and features that depend on
it.

Signed-off-by: Maxime Coquelin <redacted>

I wonder if it's better to fail instead of a mask as a start.

I think it is better to use a mask and not fail, so that we can in the
future use a recent VDUSE application with an older kernel.

Why would it be better to fail than negotiating?

Thanks,
Maxime

Thanks

quoted

---
  drivers/vdpa/vdpa_user/vduse_dev.c | 37 ++++++++++++++++++++++++++++++
  1 file changed, 37 insertions(+)

diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c
index 0486ff672408..fe4b5c8203fd 100644
--- a/drivers/vdpa/vdpa_user/vduse_dev.c
+++ b/drivers/vdpa/vdpa_user/vduse_dev.c

@@ -28,6 +28,7 @@
  #include <uapi/linux/virtio_config.h>
  #include <uapi/linux/virtio_ids.h>
  #include <uapi/linux/virtio_blk.h>
+#include <uapi/linux/virtio_ring.h>
  #include <linux/mod_devicetable.h>

  #include "iova_domain.h"

@@ -46,6 +47,30 @@

  #define IRQ_UNBOUND -1

+#define VDUSE_NET_VALID_FEATURES_MASK           \
+       (BIT_ULL(VIRTIO_NET_F_CSUM) |           \
+        BIT_ULL(VIRTIO_NET_F_GUEST_CSUM) |     \
+        BIT_ULL(VIRTIO_NET_F_MTU) |            \
+        BIT_ULL(VIRTIO_NET_F_MAC) |            \
+        BIT_ULL(VIRTIO_NET_F_GUEST_TSO4) |     \
+        BIT_ULL(VIRTIO_NET_F_GUEST_TSO6) |     \
+        BIT_ULL(VIRTIO_NET_F_GUEST_ECN) |      \
+        BIT_ULL(VIRTIO_NET_F_GUEST_UFO) |      \
+        BIT_ULL(VIRTIO_NET_F_HOST_TSO4) |      \
+        BIT_ULL(VIRTIO_NET_F_HOST_TSO6) |      \
+        BIT_ULL(VIRTIO_NET_F_HOST_ECN) |       \
+        BIT_ULL(VIRTIO_NET_F_HOST_UFO) |       \
+        BIT_ULL(VIRTIO_NET_F_MRG_RXBUF) |      \
+        BIT_ULL(VIRTIO_NET_F_STATUS) |         \
+        BIT_ULL(VIRTIO_NET_F_HOST_USO) |       \
+        BIT_ULL(VIRTIO_F_ANY_LAYOUT) |         \
+        BIT_ULL(VIRTIO_RING_F_INDIRECT_DESC) | \
+        BIT_ULL(VIRTIO_RING_F_EVENT_IDX) |          \
+        BIT_ULL(VIRTIO_F_VERSION_1) |          \
+        BIT_ULL(VIRTIO_F_ACCESS_PLATFORM) |     \
+        BIT_ULL(VIRTIO_F_RING_PACKED) |        \
+        BIT_ULL(VIRTIO_F_IN_ORDER))
+
  struct vduse_virtqueue {
         u16 index;
         u16 num_max;

@@ -1782,6 +1807,16 @@ static struct attribute *vduse_dev_attrs[] = {

  ATTRIBUTE_GROUPS(vduse_dev);

+static void vduse_dev_features_filter(struct vduse_dev_config *config)
+{
+       /*
+        * Temporarily filter out virtio-net's control virtqueue and features
+        * that depend on it while CVQ is being made more robust for VDUSE.
+        */
+       if (config->device_id == VIRTIO_ID_NET)
+               config->features &= VDUSE_NET_VALID_FEATURES_MASK;
+}
+
  static int vduse_create_dev(struct vduse_dev_config *config,
                             void *config_buf, u64 api_version)
  {

@@ -1797,6 +1832,8 @@ static int vduse_create_dev(struct vduse_dev_config *config,
         if (!dev)
                 goto err;

+       vduse_dev_features_filter(config);
+
         dev->api_version = api_version;
         dev->device_features = config->features;
         dev->device_id = config->device_id;
--

2.43.0