[PATCH v1] vdpa/mlx5: Don't free QP buffers if destroying the QP fails

[PATCH v1] vdpa/mlx5: Don't free QP buffers if destroying the QP fails

[Yuho Choi]

qp_destroy() only warns when DESTROY_QP fails and then frees the RQ
buffer and doorbell record of the driver-owned QP anyway. The QP still
exists in firmware, so the device can keep reading WQEs and the doorbell
record from memory that has been returned to the allocator. This is
reachable from teardown_vq(), which destroys the QPs even when
destroy_virtqueue() fails and the virtqueue still uses them.

Return after the warning, as cq_destroy() does, and leak the buffers
instead. A device in internal error is not affected, since the mlx5 core
reports success for DESTROY_QP in that state.

Fixes: 1a86b377aa21 ("vdpa/mlx5: Add VDPA driver for supported mlx5 devices")
Signed-off-by: Yuho Choi <oss.patchbox@gmail.com>
---
 drivers/vdpa/mlx5/net/mlx5_vnet.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c b/drivers/vdpa/mlx5/net/mlx5_vnet.c
index 8563fec2855d..a01cd890bb58 100644
--- a/drivers/vdpa/mlx5/net/mlx5_vnet.c
+++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c
@@ -483,8 +483,11 @@ static void qp_destroy(struct mlx5_vdpa_net *ndev, struct mlx5_vdpa_qp *vqp)
 	MLX5_SET(destroy_qp_in, in, opcode, MLX5_CMD_OP_DESTROY_QP);
 	MLX5_SET(destroy_qp_in, in, qpn, vqp->mqp.qpn);
 	MLX5_SET(destroy_qp_in, in, uid, ndev->mvdev.res.uid);
-	if (mlx5_cmd_exec_in(ndev->mvdev.mdev, destroy_qp, in))
+	if (mlx5_cmd_exec_in(ndev->mvdev.mdev, destroy_qp, in)) {
+		/* The QP still owns its buffers */
 		mlx5_vdpa_warn(&ndev->mvdev, "destroy qp 0x%x\n", vqp->mqp.qpn);
+		return;
+	}
 	if (!vqp->fw) {
 		mlx5_db_free(ndev->mvdev.mdev, &vqp->db);
 		rq_buf_free(ndev, vqp);

base-commit: fd179f8a05be3ccae366b9b96e176b51fbe54aab
-- 
2.43.0

Re: [PATCH v1] vdpa/mlx5: Don't free QP buffers if destroying the QP fails

[sashiko-bot]

> qp_destroy() only warns when DESTROY_QP fails and then frees the RQ
> buffer and doorbell record of the driver-owned QP anyway. The QP still
> exists in firmware, so the device can keep reading WQEs and the doorbell
> record from memory that has been returned to the allocator. This is
> reachable from teardown_vq(), which destroys the QPs even when
> destroy_virtqueue() fails and the virtqueue still uses them.
> 
> Return after the warning, as cq_destroy() does, and leak the buffers
> instead. A device in internal error is not affected, since the mlx5 core
> reports success for DESTROY_QP in that state.
> 
> Fixes: 1a86b377aa21 ("vdpa/mlx5: Add VDPA driver for supported mlx5 devices")
> Signed-off-by: Yuho Choi <oss.patchbox@gmail.com>

Sashiko has reviewed this patch and found no issues. It looks great!

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260926215632.1343807-1-oss.patchbox@gmail.com?part=1