On Sat, Feb 15, 2025 at 05:53:13PM +0800, Baolu Lu wrote: > On 2/14/25 20:41, Jason Gunthorpe wrote: > > On Fri, Feb 14, 2025 at 01:39:52PM +0800, Baolu Lu wrote: > > > > > When the IOMMU is working in scalable mode, PASID and PRI are supported. > > > ATS will always be enabled, even if the identity domain is attached to > > > the device, because the PASID might use PRI, which depends on ATS > > > functionality. This might not be the best choice, but it is the > > > simplest and functional. > > The arm driver keeps track of things and enables ATS when PASIDs are > > present > > I am not aware of any VT-d hardware implementation that supports > scalable mode but not PASID. If there were one, it would be worthwhile > to add an optimization to avoid enabling ATS during probe if PASID is > not supported. I mean domains attached to PASIDs that need PRI/ATS/etc > > Although, I'm wondering now, that check should be on the SVA paths as > > well as the iommufd path.. > > That appears to be a fix. Does SVA have the same issue? Jason
