Re: [PATCH v10 08/12] cxl: Reject CXL Reset on multifunction devices

[Srirangan Madhavan <smadhavan@nvidia.com>]

On 8/26/26 11:47 AM, Lucero Palau, Alejandro wrote:
> I think I'm the one to blame for adding this patch after my comment in
> v9 ... and to blame because I think it is not needed after all.
> 
> 
> I thought the reset_method() and the reset() sysfs files would be
> specifically created for this cxl reset functionality, but they are pci
> related and will be for any function. Because the check already present
> in v9 in cxl_reset_dvsec, non-PF0 functions can not have the cxl_reset
> method, what is good enough. So multipf can be supported and this check
> removed, as no non-PF0 function can use the potential memdev if PF0 is
> not using it, what is already ensured in your patchset.
> 
> 
> Maybe to add some warning/info when someone tries to configure cxl_reset
> for a non-PF0 function, like "PF0 owns the CXL functionality".
> 
> 
> In any case, apologies for the confusion.
> 
> 
> Thanks,
> 
> Alejandro.

No worries, and thanks for following up.

I agree that the existing DVSEC checks prevent non-PF0 functions from 
advertising cxl_reset. However, Dan’s later feedback was to keep the 
simple dev->multifunction rejection for now and handle the 
function-0-only exception as a follow-up if needed. I retained that 
conservative check in v11 and applied the same
check to cxl_bus, with the requested credit to Alex.

I did not add a warning for non-PF0 functions because returning -ENOTTY 
during reset-method probing should already prevent the unsupported 
method from being advertise.
-- 
Regards,
Srirangan