On Tue, Mar 18, 2025 at 07:31:36PM +0100, Eric Auger wrote: > Nevertheless I don't think anything prevents the acceleration granted > device from also working with virtio/vhost devices for instance unless > you unplug the existing infra.
If the accel mode is using something like vcmdq then it is not possible to work since the invalidations won't even be trapped. Even in the case where we trap the invalidations it sure is complicated.. invalidation is done by ASID which is not obviously related to any specific device. An ASID could be hidden inside a CD table that is being HW accessed and also inside a CD table that is SW accessed. The VMM has no way to know what is going on so you'd end up forced to replicate all the ASID invalidations. :\ It just doesn't seem worthwhile to try to make it all work. I'd suggest arranging to share some of the SMMUv3 emulation code, maybe with a library/headerfile or something, but I think it does make sense they would be different implementations given how completely different they should be. Jason
