On Thu, Jun 06, 2024 at 11:44:58AM -0700, Nicolin Chen wrote: > On Thu, Jun 06, 2024 at 03:24:23PM -0300, Jason Gunthorpe wrote: > > On Sun, Jun 02, 2024 at 08:25:34PM -0700, Nicolin Chen wrote: > > > > > > I understand the appeal of doing this has been to minimize qemu > > > > changes in its ACPI parts if we tackle that instead maybe we should > > > > just not implement viommu to multiple piommu. It is somewhat > > > > complicated. > > > > > > Would you please clarify that suggestion "not implement viommu > > > to multiple piommu"? > > > > > > For regular nesting (SMMU), we are still doing one vSMMU in the > > > VMM, though VCMDQ case would be an exception.... > > > > This is what I mean, always do multiple vSMMU if there are multiple > > physical pSMMUs. Don't replicate any virtual commands across pSMMUs. > > Thanks for clarifying. That also means you'd prefer putting the > command dispatcher in VMM, which is what we have at this moment. Unless someone knows a reason why we should strive hard to have only a single vSMMU and accept some invalidation inefficiency? Jason
