On Mon, Feb 02, 2026 at 03:38:50PM +0000, Shameer Kolothum Thodi wrote: > > We can treat ATS as a per-PCIe device property.. I think it would be > > fine to tell the SMMU that it always has ATS support, it will never do > > anything with it unless it sees a PCIe device with an ATS cap, and the > > physical STE generated by the hypervisor should sanitize the EATS. > > > > BIOS overriding it should be reflected as the devices being reported > > as not supporting ATS, qemu should have a per-device flag to disable > > ATS. > > Do we have way to detect that(IOMMU_FWSPEC_PCI_RC_ATS) from > userspace now?
I don't think so.. I was describing how I suspect that should work. The iommu driver is the only entity that decides if ATS should be enabled per-device, so it should report back to userspace in iommufd if the device is allowed to enable ATS or not. That should roll up any FW overrides and the PCI cap block. Jason
