Re: [PATCH v4 15/16] iommu/amd: Refactor logic to program the host page table in DTE

[Suthikulpanit, Suravee]

On 11/9/2025 6:03 AM, Jason Gunthorpe wrote:
> On Sat, Nov 08, 2025 at 10:56:38PM +0530, Vasant Hegde wrote:
> > On 10/23/2025 6:38 PM, Jason Gunthorpe wrote: 
> > > On Tue, Oct 21, 2025 at 01:43:23AM +0000, Suravee Suthikulpanit wrote:
> > >
> > > (though how does IDENTITY on a device with a PASID installed work?)
> >
> > Probably set_dte_identity() should call  set_dte_gcr3_table () and update
> > relevant fields.

Actually, PASID would not work with IDENTITY since it has no page table 
(i.e. iommu=pt means DTE[Mode]=0 and does not have host table pointer).
PASID only work with GCR3 table.

Therefore, it does not make sense for set_dte_identity() to call 
set_dte_gcr3_table(). Each one should be stand alone.

Thanks,
Suravee

> Yeah, maybe so, though it might be best if the caller can detect it
> and have it call both functions instead of trying to bury it.
>
> There is a fair number of variations here as you have
> blocked/identity, RID/PASID attach and PASID detach to all consider.
>
> It would be nice if it worked properly, identity on RID while PASID is
> in use has a strong real use case.
>
> Jason