[PATCH RFCv1 1/3] PCI: Allow ATS to be always on for CXL.cache capable devices

[Jason Gunthorpe]

On Thu, Jan 22, 2026 at 08:29:10AM -0800, Nicolin Chen wrote:
> On Thu, Jan 22, 2026 at 09:14:32AM -0400, Jason Gunthorpe wrote:
> > On Wed, Jan 21, 2026 at 09:44:32PM -0800, dan.j.williams at intel.com wrote:
> > > "We have a less than perfect legacy way (PCI untrusted flag) to nod at
> > >  ATS security problems. Let us ignore even that for a new class of
> > >  devices that advertise they can trigger all the old security problems
> > >  plus new ones."
> > 
> > Ah, I missed that we are already force disabling ATS in this untrusted
> > case, so we should ensure that continues to be the case here
> > too. Nicolin does it need a change?
> 
> pci_ats_always_on() validates against !pci_ats_supported(pdev), so
> we ensured that untrusted devices would not be always on.
> 
> Perhaps we should highlight in the commit message, as it's a topic?

Yes

Jason