Re: [PATCH v2 1/1] vfio/nvgrace-gpu: Add Blackwell-Next GPU readiness check via CXL DVSEC

[Ankit Agrawal]

Thanks Alex and Kevin for the valuable comments!

> > +
> > +           if (dvsec_memory_status & PCI_DVSEC_CXL_MEM_ACTIVE)
> > +                   return 0;
> 
> Do we need to monitor PCI_DVSEC_CXL_MEM_INFO_VALID in the loop too?

I think you are making a very valid point. The CXL spec 4.0 in Tables 8-13 states
Memory_Info_Valid: "Must be set within 1 second of reset deassertion.". So
it is possible that the Memory_Info_Valid may not be set when the software
is making this check until 1 sec. So yes, we would have to check for that as well.

> is that bit static or dynamic? If static, better to check it one-off in
> probe instead of doing it in every wait.

It is dynamic per the language on the same table 8-13 on Memory_Info_Valid
that Memory_Info_Valid: ... "Must be set within 1 second of reset deassertion."