Re: [PATCH v26 0/8] Type2 device basic support

[Dave Jiang <dave.jiang@intel.com>]

On 4/23/26 11:05 AM, alejandro.lucero-palau@amd.com wrote:
> From: Alejandro Lucero <alucerop@amd.com>
> 
> I feel this version suits better a RFC based on v25 plus the changes
> introduced. It tries to address the problem of user space actions
> triggering accelerator region removal, and extending Dan's approach
> in here:
> 
> https://lore.kernel.org/linux-cxl/20260403210050.1058650-1-dan.j.williams@intel.com/T/#m2d9e5c59ce4873641037f9bcd2f70d5679cda03c
> 
> As discussed there, the protection needs to cover the accelerator driver
> handling of the region physical range for things like ioremap, and to
> offer a way for such driver to undo things or at least stop using that
> very same physical range if the region disappears. It ends up merging
> several of v25 patches into just one.
> 
> Another change is linking the region release to the endpoint device and
> keep with Dan's autoremove. This makes unnecessary the previous cxl_exit
> and similar actions are now performed inside region detach callback.

So this would only work if the region is single device right? Which is fine for initial implementation. Maybe make a comment in the code that this is the assumption being made for the person one day needing to deal with the possibility of interleaving.

DJ

> 
> I think the outcome is quite promising, lowering the accelerator driver
> complexity regarding region handling. The cost is those new callbacks
> which I think are totally necessary for doing things safely with the
> region by the driver.
> 
> I have successfully tested the cases of cxl_acpi removal while sfc
> driver remaining, and cxl_mem unbinding sfc cxl memdev.
> 
> v26 changes:
>  - patch 6: it implements all the new functionlity described above.
>  - patch 8: region detach callback invokes a new sfc function for safely
> 	    stopping cxl-backed piobufs use.
> 
> Alejandro Lucero (8):
>   sfc: add cxl support
>   cxl/sfc: Map cxl regs
>   cxl/sfc: Initialize dpa without a mailbox
>   cxl: Prepare memdev creation for type2
>   sfc: create type2 cxl memdev
>   cxl: attach region to an accelerator/type2 memdev
>   cxl: Avoid dax creation for accelerators
>   sfc: support pio mapping based on cxl
> 
>  drivers/cxl/core/core.h               |   2 +
>  drivers/cxl/core/mbox.c               |  51 +---------
>  drivers/cxl/core/memdev.c             |  81 +++++++++++++++-
>  drivers/cxl/core/pci.c                |   1 +
>  drivers/cxl/core/port.c               |   1 +
>  drivers/cxl/core/region.c             | 125 ++++++++++++++++++++++++-
>  drivers/cxl/core/regs.c               |   1 +
>  drivers/cxl/cxlmem.h                  |   6 --
>  drivers/cxl/cxlpci.h                  |  12 ---
>  drivers/cxl/mem.c                     |  45 ++++++---
>  drivers/cxl/pci.c                     |   1 +
>  drivers/net/ethernet/sfc/Kconfig      |   9 ++
>  drivers/net/ethernet/sfc/Makefile     |   1 +
>  drivers/net/ethernet/sfc/ef10.c       |  72 +++++++++++++--
>  drivers/net/ethernet/sfc/efx.c        |  14 ++-
>  drivers/net/ethernet/sfc/efx.h        |   1 +
>  drivers/net/ethernet/sfc/efx_cxl.c    | 128 ++++++++++++++++++++++++++
>  drivers/net/ethernet/sfc/efx_cxl.h    |  31 +++++++
>  drivers/net/ethernet/sfc/net_driver.h |  12 +++
>  drivers/net/ethernet/sfc/nic.h        |   3 +
>  include/cxl/cxl.h                     |  25 +++++
>  include/cxl/pci.h                     |  22 +++++
>  22 files changed, 552 insertions(+), 92 deletions(-)
>  create mode 100644 drivers/net/ethernet/sfc/efx_cxl.c
>  create mode 100644 drivers/net/ethernet/sfc/efx_cxl.h
>  create mode 100644 include/cxl/pci.h
> 
> 
> base-commit: 6596a02b207886e9e00bb0161c7fd59fea53c081