vdpa/mlx5: Create direct MKEYs in parallel

Use the async interface to issue MTT MKEY creation.
Extra care is taken at the allocation of FW input commands
due to the MTT tables having variable sizes depending on
MR.

The indirect MKEY is still created synchronously at the
end as the direct MKEYs need to be filled in.

This makes create_user_mr() 3-5x faster, depending on
the size of the MR.

Signed-off-by: Dragos Tatulea <dtatulea@nvidia.com>
Reviewed-by: Cosmin Ratiu <cratiu@nvidia.com>
Message-Id: <20240830105838.2666587-3-dtatulea@nvidia.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

drivers/vdpa/mlx5/core/mr.c

@@ -49,17 +49,18 @@ static void populate_mtts(struct mlx5_vdpa_direct_mr *mr, __be64 *mtt)
 	}
 }
 
-static int create_direct_mr(struct mlx5_vdpa_dev *mvdev, struct mlx5_vdpa_direct_mr *mr)
+struct mlx5_create_mkey_mem {
+	u8 out[MLX5_ST_SZ_BYTES(create_mkey_out)];
+	u8 in[MLX5_ST_SZ_BYTES(create_mkey_in)];
+	__be64 mtt[];
+};
+
+static void fill_create_direct_mr(struct mlx5_vdpa_dev *mvdev,
+				  struct mlx5_vdpa_direct_mr *mr,
+				  struct mlx5_create_mkey_mem *mem)
 {
-	int inlen;
+	void *in = &mem->in;
 	void *mkc;
-	void *in;
-	int err;
-
-	inlen = MLX5_ST_SZ_BYTES(create_mkey_in) + roundup(MLX5_ST_SZ_BYTES(mtt) * mr->nsg, 16);
-	in = kvzalloc(inlen, GFP_KERNEL);
-	if (!in)
-		return -ENOMEM;
 
 	MLX5_SET(create_mkey_in, in, uid, mvdev->res.uid);
 	mkc = MLX5_ADDR_OF(create_mkey_in, in, memory_key_mkey_entry);
@@ -76,18 +77,25 @@ static int create_direct_mr(struct mlx5_vdpa_dev *mvdev, struct mlx5_vdpa_direct
 	MLX5_SET(create_mkey_in, in, translations_octword_actual_size,
 		 get_octo_len(mr->end - mr->start, mr->log_size));
 	populate_mtts(mr, MLX5_ADDR_OF(create_mkey_in, in, klm_pas_mtt));
-	err = mlx5_vdpa_create_mkey(mvdev, &mr->mr, in, inlen);
-	kvfree(in);
-	if (err) {
-		mlx5_vdpa_warn(mvdev, "Failed to create direct MR\n");
-		return err;
-	}
 
-	return 0;
+	MLX5_SET(create_mkey_in, in, opcode, MLX5_CMD_OP_CREATE_MKEY);
+	MLX5_SET(create_mkey_in, in, uid, mvdev->res.uid);
+}
+
+static void create_direct_mr_end(struct mlx5_vdpa_dev *mvdev,
+				 struct mlx5_vdpa_direct_mr *mr,
+				 struct mlx5_create_mkey_mem *mem)
+{
+	u32 mkey_index = MLX5_GET(create_mkey_out, mem->out, mkey_index);
+
+	mr->mr = mlx5_idx_to_mkey(mkey_index);
 }
 
 static void destroy_direct_mr(struct mlx5_vdpa_dev *mvdev, struct mlx5_vdpa_direct_mr *mr)
 {
+	if (!mr->mr)
+		return;
+
 	mlx5_vdpa_destroy_mkey(mvdev, mr->mr);
 }
 
@@ -179,6 +187,76 @@ static int klm_byte_size(int nklms)
 	return 16 * ALIGN(nklms, 4);
 }
 
+#define MLX5_VDPA_MTT_ALIGN 16
+
+static int create_direct_keys(struct mlx5_vdpa_dev *mvdev, struct mlx5_vdpa_mr *mr)
+{
+	struct mlx5_vdpa_async_cmd *cmds;
+	struct mlx5_vdpa_direct_mr *dmr;
+	int err = 0;
+	int i = 0;
+
+	cmds = kvcalloc(mr->num_directs, sizeof(*cmds), GFP_KERNEL);
+	if (!cmds)
+		return -ENOMEM;
+
+	list_for_each_entry(dmr, &mr->head, list) {
+		struct mlx5_create_mkey_mem *cmd_mem;
+		int mttlen, mttcount;
+
+		mttlen = roundup(MLX5_ST_SZ_BYTES(mtt) * dmr->nsg, MLX5_VDPA_MTT_ALIGN);
+		mttcount = mttlen / sizeof(cmd_mem->mtt[0]);
+		cmd_mem = kvcalloc(1, struct_size(cmd_mem, mtt, mttcount), GFP_KERNEL);
+		if (!cmd_mem) {
+			err = -ENOMEM;
+			goto done;
+		}
+
+		cmds[i].out = cmd_mem->out;
+		cmds[i].outlen = sizeof(cmd_mem->out);
+		cmds[i].in = cmd_mem->in;
+		cmds[i].inlen = struct_size(cmd_mem, mtt, mttcount);
+
+		fill_create_direct_mr(mvdev, dmr, cmd_mem);
+
+		i++;
+	}
+
+	err = mlx5_vdpa_exec_async_cmds(mvdev, cmds, mr->num_directs);
+	if (err) {
+
+		mlx5_vdpa_err(mvdev, "error issuing MTT mkey creation for direct mrs: %d\n", err);
+		goto done;
+	}
+
+	i = 0;
+	list_for_each_entry(dmr, &mr->head, list) {
+		struct mlx5_vdpa_async_cmd *cmd = &cmds[i++];
+		struct mlx5_create_mkey_mem *cmd_mem;
+
+		cmd_mem = container_of(cmd->out, struct mlx5_create_mkey_mem, out);
+
+		if (!cmd->err) {
+			create_direct_mr_end(mvdev, dmr, cmd_mem);
+		} else {
+			err = err ? err : cmd->err;
+			mlx5_vdpa_err(mvdev, "error creating MTT mkey [0x%llx, 0x%llx]: %d\n",
+				dmr->start, dmr->end, cmd->err);
+		}
+	}
+
+done:
+	for (i = i-1; i >= 0; i--) {
+		struct mlx5_create_mkey_mem *cmd_mem;
+
+		cmd_mem = container_of(cmds[i].out, struct mlx5_create_mkey_mem, out);
+		kvfree(cmd_mem);
+	}
+
+	kvfree(cmds);
+	return err;
+}
+
 static int create_indirect_key(struct mlx5_vdpa_dev *mvdev, struct mlx5_vdpa_mr *mr)
 {
 	int inlen;
@@ -279,14 +357,8 @@ static int map_direct_mr(struct mlx5_vdpa_dev *mvdev, struct mlx5_vdpa_direct_mr
 		goto err_map;
 	}
 
-	err = create_direct_mr(mvdev, mr);
-	if (err)
-		goto err_direct;
-
 	return 0;
 
-err_direct:
-	dma_unmap_sg_attrs(dma, mr->sg_head.sgl, mr->nsg, DMA_BIDIRECTIONAL, 0);
 err_map:
 	sg_free_table(&mr->sg_head);
 	return err;
@@ -401,6 +473,10 @@ static int create_user_mr(struct mlx5_vdpa_dev *mvdev,
 	if (err)
 		goto err_chain;
 
+	err = create_direct_keys(mvdev, mr);
+	if (err)
+		goto err_chain;
+
 	/* Create the memory key that defines the guests's address space. This
 	 * memory key refers to the direct keys that contain the MTT
 	 * translations