On Tue, Nov 04, 2025 at 03:45:52PM -0400, Jason Gunthorpe wrote: > On Tue, Nov 04, 2025 at 11:43:07AM -0800, Nicolin Chen wrote: > > > Right, but qemu has no way to duplicate that behavior unless it walks > > > the full s1 and s2 page tables, which we have said it isn't going to > > > do. > > > > I think it could. > > > > The stage-1 page table is in the guest RAM. And vSMMU has already > > implemented the logic to walk through a guest page table. What KVM > > has already been doing today is to ask vSMMU to translate that. > > No, we can't. The existing vsmmu code could do it because it mediated > the invalidation path. As soon as you have something like vcmdq the > hypervisor cannot walk the page tables.
Hmm? It does walk through the page table (not invalidation path): https://github.com/qemu/qemu/blob/master/hw/arm/smmu-common.c#L444 And VCMDQ can work with that. We've tested it.. Nicolin
