vdpa/mlx5: Use vq suspend/resume during .set_map

Instead of tearing down and setting up vq resources, use vq
suspend/resume during .set_map to speed things up a bit.

The vq mr is updated with the new mapping while the vqs are suspended.

If the device doesn't support resumable vqs, do the old teardown and
setup dance.
Reviewed-by: Gal Pressman <gal@nvidia.com>
Acked-by: Eugenio Pérez <eperezma@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Dragos Tatulea <dtatulea@nvidia.com>
Message-Id: <20231225151203.152687-7-dtatulea@nvidia.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

drivers/vdpa/mlx5/net/mlx5_vnet.c

@@ -1206,6 +1206,7 @@ static int modify_virtqueue(struct mlx5_vdpa_net *ndev,
 {
 	int inlen = MLX5_ST_SZ_BYTES(modify_virtio_net_q_in);
 	u32 out[MLX5_ST_SZ_DW(modify_virtio_net_q_out)] = {};
+	struct mlx5_vdpa_dev *mvdev = &ndev->mvdev;
 	bool state_change = false;
 	void *obj_context;
 	void *cmd_hdr;
@@ -1255,6 +1256,24 @@ static int modify_virtqueue(struct mlx5_vdpa_net *ndev,
 	if (mvq->modified_fields & MLX5_VIRTQ_MODIFY_MASK_VIRTIO_Q_USED_IDX)
 		MLX5_SET(virtio_net_q_object, obj_context, hw_used_index, mvq->used_idx);
 
+	if (mvq->modified_fields & MLX5_VIRTQ_MODIFY_MASK_VIRTIO_Q_MKEY) {
+		struct mlx5_vdpa_mr *mr = mvdev->mr[mvdev->group2asid[MLX5_VDPA_DATAVQ_GROUP]];
+
+		if (mr)
+			MLX5_SET(virtio_q, vq_ctx, virtio_q_mkey, mr->mkey);
+		else
+			mvq->modified_fields &= ~MLX5_VIRTQ_MODIFY_MASK_VIRTIO_Q_MKEY;
+	}
+
+	if (mvq->modified_fields & MLX5_VIRTQ_MODIFY_MASK_DESC_GROUP_MKEY) {
+		struct mlx5_vdpa_mr *mr = mvdev->mr[mvdev->group2asid[MLX5_VDPA_DATAVQ_DESC_GROUP]];
+
+		if (mr && MLX5_CAP_DEV_VDPA_EMULATION(mvdev->mdev, desc_group_mkey_supported))
+			MLX5_SET(virtio_q, vq_ctx, desc_group_mkey, mr->mkey);
+		else
+			mvq->modified_fields &= ~MLX5_VIRTQ_MODIFY_MASK_DESC_GROUP_MKEY;
+	}
+
 	MLX5_SET64(virtio_net_q_object, obj_context, modify_field_select, mvq->modified_fields);
 	err = mlx5_cmd_exec(ndev->mvdev.mdev, in, inlen, out, sizeof(out));
 	if (err)
@@ -2784,24 +2803,35 @@ static int mlx5_vdpa_change_map(struct mlx5_vdpa_dev *mvdev,
 				unsigned int asid)
 {
 	struct mlx5_vdpa_net *ndev = to_mlx5_vdpa_ndev(mvdev);
+	bool teardown = !is_resumable(ndev);
 	int err;
 
 	suspend_vqs(ndev);
-	err = save_channels_info(ndev);
-	if (err)
-		return err;
+	if (teardown) {
+		err = save_channels_info(ndev);
+		if (err)
+			return err;
 
-	teardown_driver(ndev);
+		teardown_driver(ndev);
+	}
 
 	mlx5_vdpa_update_mr(mvdev, new_mr, asid);
 
+	for (int i = 0; i < ndev->cur_num_vqs; i++)
+		ndev->vqs[i].modified_fields |= MLX5_VIRTQ_MODIFY_MASK_VIRTIO_Q_MKEY |
+						MLX5_VIRTQ_MODIFY_MASK_DESC_GROUP_MKEY;
+
 	if (!(mvdev->status & VIRTIO_CONFIG_S_DRIVER_OK) || mvdev->suspended)
 		return 0;
 
-	restore_channels_info(ndev);
-	err = setup_driver(mvdev);
-	if (err)
-		return err;
+	if (teardown) {
+		restore_channels_info(ndev);
+		err = setup_driver(mvdev);
+		if (err)
+			return err;
+	}
+
+	resume_vqs(ndev);
 
 	return 0;
 }

include/linux/mlx5/mlx5_ifc_vdpa.h

@@ -148,6 +148,7 @@ enum {
 	MLX5_VIRTQ_MODIFY_MASK_VIRTIO_Q_ADDRS           = (u64)1 << 6,
 	MLX5_VIRTQ_MODIFY_MASK_VIRTIO_Q_AVAIL_IDX       = (u64)1 << 7,
 	MLX5_VIRTQ_MODIFY_MASK_VIRTIO_Q_USED_IDX        = (u64)1 << 8,
+	MLX5_VIRTQ_MODIFY_MASK_VIRTIO_Q_MKEY            = (u64)1 << 11,
 	MLX5_VIRTQ_MODIFY_MASK_DESC_GROUP_MKEY          = (u64)1 << 14,
 };