RE: [PATCH v6 0/6] iommufd: Add nesting infrastructure (part 2/2)

From: Jason Gunthorpe jgg@nvidia.com Sent: Saturday, December 9, 2023 9:47 AM

What is in a Nested domain: Intel: A single IO page table refereed to by a PASID entry Each vDomain-ID,PASID allocates a unique nesting domain AMD: A GCR3 table pointer Nesting domains are created for every unique GCR3 pointer. vDomain-ID can possibly refer to multiple Nesting domains :( ARM: A CD table pointer Nesting domains are created for every unique CD table top pointer.

this AMD/ARM difference is not very clear to me.

How could a vDomain-ID refer to multiple GCR3 pointers? Wouldn't it lead to cache tag conflict when a same PASID entry in multiple GCR3 tables points to different I/O page tables?