Re: [PATCH v11 00/12] PCI/CXL: Add CXL reset support for Type 2 devices

[Alex Williamson]

On Wed,  2 Sep 2026 07:27:52 +0000
Srirangan Madhavan <smadhavan@xxxxxxxxxx> wrote:

> Hi folks!
> 
> This series adds CXL Reset support for CXL Type 2 devices through the
> existing PCI reset_method ABI. The reset sequence follows the CXL 4.0
> specification [1], including CXL.cache disable, optional cache
> writeback, CXL Reset initiation, ResetComplete polling, and ResetError
> reporting.
> 
> The userspace ABI is the existing PCI reset interface:
> 
>     /sys/bus/pci/devices/.../reset_method
>     /sys/bus/pci/devices/.../reset
> 
> Userspace can select "cxl_reset" in reset_method and then trigger reset
> through the existing reset attribute.
> 
> CXL Reset is exposed conservatively. The target must be a
> single-function CXL Type 2 device with CXL.cache and CXL.mem enabled,
> and the kernel must have cached HDM state sufficient to validate affected
> ranges and restore decoder programming. The reset preserves device
> memory; it does not request CXL Reset Memory Clear.

How does this provide multi-tenancy then?  vfio-pci considers the
device to be scrubbed of tenant data after a pci_reset_function() and
I don't think Manish's series alters that.  Thanks,

Alex