vdpa/mlx5: Add VDPA driver for supported mlx5 devices

Add a front end VDPA driver that registers in the VDPA bus and provides
networking to a guest. The VDPA driver creates the necessary resources
on the VF it is driving such that data path will be offloaded.

Notifications are being communicated through the driver.

Currently, only VFs are supported. In subsequent patches we will have
devlink support to control which VF is used for VDPA and which function
is used for regular networking.

Reviewed-by: Parav Pandit <parav@mellanox.com>
Signed-off-by: Eli Cohen <eli@mellanox.com>
Link: https://lore.kernel.org/r/20200804162048.22587-13-eli@mellanox.com
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>

drivers/vdpa/Kconfig

@@ -37,4 +37,14 @@ config MLX5_VDPA
 	  common for all types of VDPA drivers. The following drivers are planned:
 	  net, block.
 
+config MLX5_VDPA_NET
+	tristate "vDPA driver for ConnectX devices"
+	depends on MLX5_VDPA
+	default n
+	help
+	  VDPA network driver for ConnectX6 and newer. Provides offloading
+	  of virtio net datapath such that descriptors put on the ring will
+	  be executed by the hardware. It also supports a variety of stateless
+	  offloads depending on the actual device used and firmware version.
+
 endif # VDPA

drivers/vdpa/mlx5/Makefile

@@ -1 +1,4 @@
-obj-$(CONFIG_MLX5_VDPA) += core/resources.o core/mr.o
+subdir-ccflags-y += -I$(srctree)/drivers/vdpa/mlx5/core
+
+obj-$(CONFIG_MLX5_VDPA_NET) += mlx5_vdpa.o
+mlx5_vdpa-$(CONFIG_MLX5_VDPA_NET) += net/main.o net/mlx5_vnet.o core/resources.o core/mr.o

drivers/vdpa/mlx5/core/mr.c

@@ -464,7 +464,7 @@ int mlx5_vdpa_handle_set_map(struct mlx5_vdpa_dev *mvdev, struct vhost_iotlb *io
 			     bool *change_map)
 {
 	struct mlx5_vdpa_mr *mr = &mvdev->mr;
-	int err;
+	int err = 0;
 
 	*change_map = false;
 	if (map_empty(iotlb)) {

drivers/vdpa/mlx5/net/main.c

@@ -0,0 +1,76 @@
+// SPDX-License-Identifier: GPL-2.0 OR Linux-OpenIB
+/* Copyright (c) 2020 Mellanox Technologies Ltd. */
+
+#include <linux/module.h>
+#include <linux/mlx5/driver.h>
+#include <linux/mlx5/device.h>
+#include "mlx5_vdpa_ifc.h"
+#include "mlx5_vnet.h"
+
+MODULE_AUTHOR("Eli Cohen <eli@mellanox.com>");
+MODULE_DESCRIPTION("Mellanox VDPA driver");
+MODULE_LICENSE("Dual BSD/GPL");
+
+static bool required_caps_supported(struct mlx5_core_dev *mdev)
+{
+	u8 event_mode;
+	u64 got;
+
+	got = MLX5_CAP_GEN_64(mdev, general_obj_types);
+
+	if (!(got & MLX5_GENERAL_OBJ_TYPES_CAP_VIRTIO_NET_Q))
+		return false;
+
+	event_mode = MLX5_CAP_DEV_VDPA_EMULATION(mdev, event_mode);
+	if (!(event_mode & MLX5_VIRTIO_Q_EVENT_MODE_QP_MODE))
+		return false;
+
+	if (!MLX5_CAP_DEV_VDPA_EMULATION(mdev, eth_frame_offload_type))
+		return false;
+
+	return true;
+}
+
+static void *mlx5_vdpa_add(struct mlx5_core_dev *mdev)
+{
+	struct mlx5_vdpa_dev *vdev;
+
+	if (mlx5_core_is_pf(mdev))
+		return NULL;
+
+	if (!required_caps_supported(mdev)) {
+		dev_info(mdev->device, "virtio net emulation not supported\n");
+		return NULL;
+	}
+	vdev = mlx5_vdpa_add_dev(mdev);
+	if (IS_ERR(vdev))
+		return NULL;
+
+	return vdev;
+}
+
+static void mlx5_vdpa_remove(struct mlx5_core_dev *mdev, void *context)
+{
+	struct mlx5_vdpa_dev *vdev = context;
+
+	mlx5_vdpa_remove_dev(vdev);
+}
+
+static struct mlx5_interface mlx5_vdpa_interface = {
+	.add = mlx5_vdpa_add,
+	.remove = mlx5_vdpa_remove,
+	.protocol = MLX5_INTERFACE_PROTOCOL_VDPA,
+};
+
+static int __init mlx5_vdpa_init(void)
+{
+	return mlx5_register_interface(&mlx5_vdpa_interface);
+}
+
+static void __exit mlx5_vdpa_exit(void)
+{
+	mlx5_unregister_interface(&mlx5_vdpa_interface);
+}
+
+module_init(mlx5_vdpa_init);
+module_exit(mlx5_vdpa_exit);