Re: [PATCH vhost v4 00/16] vdpa: Add support for vq descriptor mappings

[Michael S. Tsirkin]

On Wed, Oct 18, 2023 at 08:14:39PM +0300, Dragos Tatulea wrote:
> This patch series adds support for vq descriptor table mappings which
> are used to improve vdpa live migration downtime. The improvement comes
> from using smaller mappings which take less time to create and destroy
> in hw.
> 
> The first part adds the vdpa core changes from Si-Wei [0].
> 
> The second part adds support in mlx5_vdpa:
> - Refactor the mr code to be able to cleanly add descriptor mappings.
> - Add hardware descriptor mr support.
> - Properly update iotlb for cvq during ASID switch.
> 
> Changes in v4:
> 
> - Improved the handling of empty iotlbs. See mlx5_vdpa_change_map
>   section in patch "12/16 vdpa/mlx5: Improve mr upate flow".
> - Fixed a invalid usage of desc_group_mkey hw vq field when the
>   capability is not there. See patch
>   "15/16 vdpa/mlx5: Enable hw support for vq descriptor map".

At this point, whether this patchset makes it in 6.7 will largely depend
on how many rcs there are in 6.6, so it can get some time in next.


> Changes in v3:
> 
> - dup_iotlb now checks for src == dst case and returns an error.
> - Renamed iotlb parameter in dup_iotlb to dst.
> - Removed a redundant check of the asid value.
> - Fixed a commit message.
> - mx5_ifc.h patch has been applied to mlx5-vhost tree. When applying
>   this series please pull from that tree first.
> 
> Changes in v2:
> 
> - The "vdpa/mlx5: Enable hw support for vq descriptor mapping" change
>   was split off into two patches to avoid merge conflicts into the tree
>   of Linus.
> 
>   The first patch contains only changes for mlx5_ifc.h. This must be
>   applied into the mlx5-vdpa tree [1] first. Once this patch is applied
>   on mlx5-vdpa, the change has to be pulled fom mlx5-vdpa into the vhost
>   tree and only then the remaining patches can be applied.
> 
> [0] https://lore.kernel.org/virtualization/1694248959-13369-1-git-send-email-si-wei.liu@xxxxxxxxxx
> [1] https://git.kernel.org/pub/scm/linux/kernel/git/mellanox/linux.git/log/?h=mlx5-vhost
> 
> Dragos Tatulea (13):
>   vdpa/mlx5: Expose descriptor group mkey hw capability
>   vdpa/mlx5: Create helper function for dma mappings
>   vdpa/mlx5: Decouple cvq iotlb handling from hw mapping code
>   vdpa/mlx5: Take cvq iotlb lock during refresh
>   vdpa/mlx5: Collapse "dvq" mr add/delete functions
>   vdpa/mlx5: Rename mr destroy functions
>   vdpa/mlx5: Allow creation/deletion of any given mr struct
>   vdpa/mlx5: Move mr mutex out of mr struct
>   vdpa/mlx5: Improve mr update flow
>   vdpa/mlx5: Introduce mr for vq descriptor
>   vdpa/mlx5: Enable hw support for vq descriptor mapping
>   vdpa/mlx5: Make iotlb helper functions more generic
>   vdpa/mlx5: Update cvq iotlb mapping on ASID change
> 
> Si-Wei Liu (3):
>   vdpa: introduce dedicated descriptor group for virtqueue
>   vhost-vdpa: introduce descriptor group backend feature
>   vhost-vdpa: uAPI to get dedicated descriptor group id
> 
>  drivers/vdpa/mlx5/core/mlx5_vdpa.h |  31 +++--
>  drivers/vdpa/mlx5/core/mr.c        | 194 ++++++++++++++++-------------
>  drivers/vdpa/mlx5/core/resources.c |   6 +-
>  drivers/vdpa/mlx5/net/mlx5_vnet.c  | 105 +++++++++++-----
>  drivers/vhost/vdpa.c               |  27 ++++
>  include/linux/mlx5/mlx5_ifc.h      |   8 +-
>  include/linux/mlx5/mlx5_ifc_vdpa.h |   7 +-
>  include/linux/vdpa.h               |  11 ++
>  include/uapi/linux/vhost.h         |   8 ++
>  include/uapi/linux/vhost_types.h   |   5 +
>  10 files changed, 272 insertions(+), 130 deletions(-)
> 
> -- 
> 2.41.0