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

From: Eli Cohen
Date: Sun May 30 2021 - 04:11:07 EST


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.

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];
--
2.31.1