Re: [PATCH 1/2] vdpa/mlx5: Support creating resources with uid == 0

From: Jason Wang
Date: Mon May 31 2021 - 02:44:16 EST



在 2021/5/31 下午12:59, Eli Cohen 写道:
On Mon, May 31, 2021 at 11:06:59AM +0800, Jason Wang wrote:
在 2021/5/31 上午11:02, Jason Wang 写道:
在 2021/5/30 下午3:54, Eli Cohen 写道:
Currently all resources must be created with uid != 0 which is essential
userspace processes allocating virtquueue resources. Since this is a
kernel implementation, it is perfectly legal to open resources with
uid == 0.

In case frimware supports, avoid allocating user context.

Typo "frimware".

Otherwise.

Acked-by: Jason Wang <jasowang@xxxxxxxxxx>

(I don't see any code to check the firmware capability, is this
intended?)

Speak too fast. I see the MLX5_CAP_GEN(), so it's fine.
And I responded too fast :-)


Right and thanks for the quick response :)


Thanks


Thanks


Signed-off-by: Eli Cohen <elic@xxxxxxxxxx>
---
  drivers/vdpa/mlx5/core/resources.c | 6 ++++++
  include/linux/mlx5/mlx5_ifc.h      | 4 +++-
  2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/vdpa/mlx5/core/resources.c
b/drivers/vdpa/mlx5/core/resources.c
index 6521cbd0f5c2..836ab9ef0fa6 100644
--- a/drivers/vdpa/mlx5/core/resources.c
+++ b/drivers/vdpa/mlx5/core/resources.c
@@ -54,6 +54,9 @@ static int create_uctx(struct mlx5_vdpa_dev
*mvdev, u16 *uid)
      void *in;
      int err;
  +    if (MLX5_CAP_GEN(mvdev->mdev, umem_uid_0))
+        return 0;
+
      /* 0 means not supported */
      if (!MLX5_CAP_GEN(mvdev->mdev, log_max_uctx))
          return -EOPNOTSUPP;
@@ -79,6 +82,9 @@ static void destroy_uctx(struct mlx5_vdpa_dev
*mvdev, u32 uid)
      u32 out[MLX5_ST_SZ_DW(destroy_uctx_out)] = {};
      u32 in[MLX5_ST_SZ_DW(destroy_uctx_in)] = {};
  +    if (!uid)
+        return;
+
      MLX5_SET(destroy_uctx_in, in, opcode, MLX5_CMD_OP_DESTROY_UCTX);
      MLX5_SET(destroy_uctx_in, in, uid, uid);
  diff --git a/include/linux/mlx5/mlx5_ifc.h
b/include/linux/mlx5/mlx5_ifc.h
index 9c68b2da14c6..606d2aeacad4 100644
--- a/include/linux/mlx5/mlx5_ifc.h
+++ b/include/linux/mlx5/mlx5_ifc.h
@@ -1487,7 +1487,9 @@ struct mlx5_ifc_cmd_hca_cap_bits {
      u8         uar_4k[0x1];
      u8         reserved_at_241[0x9];
      u8         uar_sz[0x6];
-    u8         reserved_at_250[0x8];
+    u8         reserved_at_248[0x2];
+    u8         umem_uid_0[0x1];
+    u8         reserved_at_250[0x5];
      u8         log_pg_sz[0x8];
        u8         bf[0x1];