Re: vdpa/mlx5: Allow CVQ size changes

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On 2/15/24 2:02 PM, Eugenio Perez Martin wrote:
On Thu, Feb 15, 2024 at 7:55 PM Eugenio Perez Martin
<eperezma@xxxxxxxxxx> wrote:

On Thu, Feb 15, 2024 at 6:05 PM Jonah Palmer <jonah.palmer@xxxxxxxxxx> wrote:

The MLX driver was not updating its control virtqueue size at set_vq_num
and instead always initialized to MLX5_CVQ_MAX_ENT (16) at
setup_cvq_vring.

Qemu would try to set the size to 64 by default, however, because the
CVQ size always was initialized to 16, an error would be thrown when
sending >16 control messages (as used-ring entry 17 is initialized to 0).
For example, starting a guest with x-svq=on and then executing the
following command would produce the error below:

  # for i in {1..20}; do ifconfig eth0 hw ether XX:xx:XX:xx:XX:XX; done

  qemu-system-x86_64: Insufficient written data (0)
  [  435.331223] virtio_net virtio0: Failed to set mac address by vq command.
  SIOCSIFHWADDR: Invalid argument

Signed-off-by: Jonah Palmer <jonah.palmer@xxxxxxxxxx>

Acked-by: Eugenio Pérez <eperezma@xxxxxxxxxx>

Thanks!

---
  drivers/vdpa/mlx5/net/mlx5_vnet.c | 10 ++++++++--
  1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c b/drivers/vdpa/mlx5/net/mlx5_vnet.c
index 778821bab7d9..c74de1fe6a94 100644
--- a/drivers/vdpa/mlx5/net/mlx5_vnet.c
+++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c
@@ -2276,9 +2276,15 @@ static void mlx5_vdpa_set_vq_num(struct vdpa_device *vdev, u16 idx, u32 num)
         struct mlx5_vdpa_net *ndev = to_mlx5_vdpa_ndev(mvdev);
         struct mlx5_vdpa_virtqueue *mvq;

-       if (!is_index_valid(mvdev, idx) || is_ctrl_vq_idx(mvdev, idx))
+       if (!is_index_valid(mvdev, idx))
                 return;

+        if (is_ctrl_vq_idx(mvdev, idx)) {
+                struct mlx5_control_vq *cvq = &mvdev->cvq;
+                cvq->vring.vring.num = num;
+                return;
+        }
+
         mvq = &ndev->vqs[idx];
         mvq->num_ent = num;
  }
@@ -2963,7 +2969,7 @@ static int setup_cvq_vring(struct mlx5_vdpa_dev *mvdev)
                 u16 idx = cvq->vring.last_avail_idx;

                 err = vringh_init_iotlb(&cvq->vring, mvdev->actual_features,
-                                       MLX5_CVQ_MAX_ENT, false,

Actually there is one nitpick: MLX5_CVQ_MAX_ENT macro should be
deleted as there are no more usages :). With that change and Dragos'
request you can post a V2 with my Acked-by included.

Thanks!

Will do, thank you!

Jonah


+                                       cvq->vring.vring.num, false,
                                         (struct vring_desc *)(uintptr_t)cvq->desc_addr,
                                         (struct vring_avail *)(uintptr_t)cvq->driver_addr,
                                         (struct vring_used *)(uintptr_t)cvq->device_addr);
--
2.39.3






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