Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Received-SPF: Pass (protection.outlook.com: domain of nvidia.com designates
 216.228.112.32 as permitted sender) receiver=protection.outlook.com;
 client-ip=216.228.112.32; helo=mail.nvidia.com;
From:   Eli Cohen <elic@nvidia.com>
To:     <mst@redhat.com>, <jasowang@redhat.com>,
        <virtualization@lists.linux-foundation.org>,
        <linux-kernel@vger.kernel.org>
CC:     <elic@nvidia.com>
Subject: [PATCH v1 1/2] vdpa/mlx5: Support creating resources with uid == 0
Date:   Mon, 31 May 2021 19:04:04 +0300
Message-ID: <20210531160404.31368-1-elic@nvidia.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Content-Type: text/plain
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 31 May 2021 16:04:12.1681
 (UTC)
X-MS-Exchange-CrossTenant-Network-Message-Id: 60507f26-d2c8-47f5-0fa5-08d9244dbb53
X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a
X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a;Ip=[216.228.112.32];Helo=[mail.nvidia.com]
X-MS-Exchange-CrossTenant-AuthSource: BN8NAM11FT061.eop-nam11.prod.protection.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Anonymous
X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem
X-MS-Exchange-Transport-CrossTenantHeadersStamped: BN6PR1201MB0004
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

Currently all resources must be created with uid != 0 which is essential
when userspace processes are allocating virtquueue resources. Since this
is a kernel implementation, it is perfectly legal to open resources with
uid == 0.

In case firmware supports, avoid allocating user context.

Signed-off-by: Eli Cohen <elic@nvidia.com>
---
v0 --> v1:
  Fix typo and modify phrasing

 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