Re: [PATCH V6 0/9] Refine virtio mapping API

["Michael S. Tsirkin" <mst@redhat.com>]

On Thu, Aug 21, 2025 at 02:46:32PM +0800, Jason Wang wrote:
> Hi all:
> 
> Virtio used to be coupled with DMA API. This works fine for the device
> that do real DMA but not the others. For example, VDUSE nees to craft
> with DMA API in order to let the virtio-vdpa driver to work.
> 
> This series tries to solve this issue by introducing the mapping API
> in the virtio core. So transport like vDPA can implement their own
> mapping logic without the need to hack with DMA API. The mapping API
> are abstracted with a new map operations in order to be re-used by
> transprot or device. So device like VDUSE can implement its own
> mapping loigc.
> 
> For device that uses DMA (for example PCI device), the virtio core
> will still call DMA API directly without the need of implementing map
> ops per device/transport.
> 
> Please review.

I sent some typos i found.
Pls send fixups on top to fix them so testing in linux-next is not invalidated.
Thanks!



> Changes since V5:
> 
> - Rename mapping_token to virtio_map
> - Do not use opaque void * pointer, just use a forward decalration of
>   vduse_iova_domain
> - Remove unused variable and typo fixes
> 
> Changes since V4:
> 
> - Rename map_token to mapping_token
> - Introduce a union container for opaque token as well as the DMA
>   device so we won't lose the type safety
> - Do not try to set DMA mask for VDUSE device
> - Introduce a new mapper_error op for API completeness
> 
> Changes since V3:
> 
> - Fix build error of PDS vDPA driver
> 
> Changes since V2:
> 
> - Drop VDUSE dependenct for HAS_DMA and ARCH_HAS_DMA_OPS
> 
> Changes since V1:
> 
> - Fix build error of mlx5_vdpa driver
> 
> 
> Jason Wang (9):
>   virtio_ring: constify virtqueue pointer for DMA helpers
>   virtio_ring: switch to use dma_{map|unmap}_page()
>   virtio: rename dma helpers
>   virtio: introduce virtio_map container union
>   virtio_ring: rename dma_handle to map_handle
>   virtio: introduce map ops in virtio core
>   vdpa: support virtio_map
>   vdpa: introduce map ops
>   vduse: switch to use virtio map API instead of DMA API
> 
>  drivers/net/virtio_net.c                 |  28 +-
>  drivers/vdpa/Kconfig                     |   8 +-
>  drivers/vdpa/alibaba/eni_vdpa.c          |   5 +-
>  drivers/vdpa/ifcvf/ifcvf_main.c          |   5 +-
>  drivers/vdpa/mlx5/core/mr.c              |   4 +-
>  drivers/vdpa/mlx5/net/mlx5_vnet.c        |  15 +-
>  drivers/vdpa/octeon_ep/octep_vdpa_main.c |   6 +-
>  drivers/vdpa/pds/vdpa_dev.c              |   5 +-
>  drivers/vdpa/solidrun/snet_main.c        |   8 +-
>  drivers/vdpa/vdpa.c                      |   5 +-
>  drivers/vdpa/vdpa_sim/vdpa_sim.c         |   4 +-
>  drivers/vdpa/vdpa_user/iova_domain.c     |   2 +-
>  drivers/vdpa/vdpa_user/iova_domain.h     |   2 +-
>  drivers/vdpa/vdpa_user/vduse_dev.c       |  79 ++--
>  drivers/vdpa/virtio_pci/vp_vdpa.c        |   5 +-
>  drivers/vhost/vdpa.c                     |   6 +-
>  drivers/virtio/virtio_ring.c             | 459 ++++++++++++++---------
>  drivers/virtio/virtio_vdpa.c             |  20 +-
>  include/linux/vdpa.h                     |  25 +-
>  include/linux/virtio.h                   |  46 ++-
>  include/linux/virtio_config.h            |  72 ++++
>  include/linux/virtio_ring.h              |   7 +-
>  22 files changed, 531 insertions(+), 285 deletions(-)
> 
> -- 
> 2.31.1