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

Nicolin Chen
2026-01-22T16:29:31Z

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@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?

Nicolin