> From: Jason Gunthorpe <jgg@xxxxxxxxxx> > Sent: Friday, June 7, 2024 8:27 AM > > 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? > migration? a single vSMMU provides better compatibility between src/dest...
