[PATCH vhost v4 13/15] vdpa/mlx5: Use vq suspend/resume during .set_map

Dragos Tatulea
2023-12-19T18:10:14Z

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>
Signed-off-by: Dragos Tatulea <dtatulea@nvidia.com>
---
drivers/vdpa/mlx5/net/mlx5_vnet.c | 46 ++++++++++++++++++++++++------
include/linux/mlx5/mlx5_ifc_vdpa.h | 1 +
2 files changed, 39 insertions(+), 8 deletions(-)

diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c b/drivers/vdpa/mlx5/net/mlx5_vnet.c
index b760005e2920..fcadbeede3e1 100644
--- a/drivers/vdpa/mlx5/net/mlx5_vnet.c
+++ b/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)
@@ -2791,24 +2810,35 @@ 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;
}
diff --git a/include/linux/mlx5/mlx5_ifc_vdpa.h b/include/linux/mlx5/mlx5_ifc_vdpa.h
index 32e712106e68..40371c916cf9 100644
--- a/include/linux/mlx5/mlx5_ifc_vdpa.h
+++ b/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,
};

--
2.43.0