Re: [PATCH] KVM: SEV: drop FOLL_LONGTERM for encrypted region registration

[Gupta, Pankaj]

On 7/10/2026 6:38 PM, David Hildenbrand (Arm) wrote:
> > > How long ago did I break this though? Why has it taken until now for this to be
> > > reported? :) commit 8ac268436e6d ("mm/gup: disallow FOLL_LONGTERM GUP-nonfast
> > > writing to file-backed mappings") is from May 2023 :)
> > The break didn't come from your changes, it came from commit 7e066cb9b71a ("KVM:
> > SEV: Use long-term pin when registering encrypted memory regions").  I suggested
> > falling back to a non-longterm pin, but David didn't like that idea :-)
> Yes, a longterm pin is a longterm pin.
>
> If we don't write to the memory, why do we need a write pin? To make sure that
> what we pin was actually unshared?
>
> Well, FOLL_LONGTERM does that nowadays.
>
>
> ... so is maybe dropping the FOLL_WRITE sufficient?

Yes, All that is correct. Sent a v2.

Thank you!

Pankaj