[PATCH vhost v5 0/8] vdpa/mlx5: Add support for resumable vqs

[Dragos Tatulea]

Add support for resumable vqs in the mlx5_vdpa driver. This is a
firmware feature that can be used for the following benefits:
- Full device .suspend/.resume.
- .set_map doesn't need to destroy and create new vqs anymore just to
  update the map. When resumable vqs are supported it is enough to
  suspend the vqs, set the new maps, and then resume the vqs.

The first patch exposes relevant bits for the feature in mlx5_ifc.h.
That means it needs to be applied to the mlx5-vhost tree [0] first. Once
applied there, the change has to be pulled from mlx5-vhost into the
vhost tree and only then the remaining patches can be applied. Same flow
as the vq descriptor mappings patchset [1].

The second part adds support for selectively modifying vq parameters. This
is needed to be able to use resumable vqs.

The third part adds the actual support for resumable vqs.

The last part of the series introduces reference counting for mrs which
is necessary to avoid freeing mkeys too early or leaking them.

* Changes in v5:
- Same as v2 with additional Acked-by tags. Based on review discussion
  in this thread [0].

* Changes in v4:
- Added vdpa backend feature support for changing vq properties in
  DRIVER_OK when device is suspended. Added support in the driver as
  well.
- Dropped Acked-by for the patches that had the tag mistakenly
  added.

* Changes in v3:
- Faulty version. Please ignore.

* Changes in v2:
- Added mr refcounting patches.
- Deleted unnecessary patch: "vdpa/mlx5: Split function into locked and
  unlocked variants"
- Small print improvement in "Introduce per vq and device resume"
  patch.
- Patch 1/7 has been applied to mlx5-vhost branch.

[0] - https://lore.kernel.org/virtualization/4abd7d516a9e82ebf41b1ea98475341844186568.camel@xxxxxxxxxx/T/#mb0433c4f1705fc2cdaa7c926f352c26f6b54444d

Dragos Tatulea (8):
  vdpa/mlx5: Expose resumable vq capability
  vdpa/mlx5: Allow modifying multiple vq fields in one modify command
  vdpa/mlx5: Introduce per vq and device resume
  vdpa/mlx5: Mark vq addrs for modification in hw vq
  vdpa/mlx5: Mark vq state for modification in hw vq
  vdpa/mlx5: Use vq suspend/resume during .set_map
  vdpa/mlx5: Introduce reference counting to mrs
  vdpa/mlx5: Add mkey leak detection

 drivers/vdpa/mlx5/core/mlx5_vdpa.h |  10 +-
 drivers/vdpa/mlx5/core/mr.c        |  69 ++++++++--
 drivers/vdpa/mlx5/net/mlx5_vnet.c  | 209 ++++++++++++++++++++++++++---
 include/linux/mlx5/mlx5_ifc.h      |   3 +-
 include/linux/mlx5/mlx5_ifc_vdpa.h |   4 +
 5 files changed, 257 insertions(+), 38 deletions(-)

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2.43.0