Re: [PATCH 6/6] ACPI: PCC: Preserve shared memory signature in OpRegion handler

[Sudeep Holla]

On Tue, Jun 30, 2026 at 02:33:08PM +0200, Rafael J. Wysocki (Intel) wrote:
> On Sat, Jun 27, 2026 at 6:39 PM Sudeep Holla <sudeep.holla@xxxxxxxxxx> wrote:
> >
> > ACPI defines a PCC OperationRegion as the shared memory fields that
> > follow the PCC signature. The OperationRegion length is likewise the
> > total size of the fields that succeed the signature in shared memory.
> >
> > ACPI 6.6 adds clarification that the PCC shared memory signature is
> > populated by the platform and verified by OSPM.
> >
> > The PCC address space handler currently copies the OperationRegion
> > buffer to and from the start of the PCC shared memory region. That can
> > overwrite or expose the signature at byte offset 0, and it also misses
> > the last 4 bytes of the actual PCC OperationRegion data.
> >
> > Offset OperationRegion copies by the size of the signature and reject
> > regions that do not fit in the shared memory after that signature.
> >
> > Cc: "Rafael J. Wysocki" <rafael@xxxxxxxxxx>
> > Fixes: 77e2a04745ff ("ACPI: PCC: Implement OperationRegion handler for the PCC Type 3 subtype")
> > Signed-off-by: Sudeep Holla <sudeep.holla@xxxxxxxxxx>
> 
> Does this depend on anything else in the series or is it independent?
> 

It is independent. This just fixes the issue of including the signature in
the opregion data. It can go independently as all other patches as well.

-- 
Regards,
Sudeep