On 4/25/2024 12:55 AM, Edgecombe, Rick P wrote:
Hi, This is a new effort to solicit community feedback for potential future TDX module features. There are two features in different stages of development around the configurability of the max physical address exposed in 0x80000008.EAX. I was hoping to get some comments on them and share the current plans on whether to implement them in KVM.
Sean and Paolo,
One of the TDX module features is called MAXPA_VIRT. In short, it is similar to KVM’s allow_smaller_maxphyaddr. It requires an explicit opt-in by the VMM, and allows a TD’s 0x80000008.EAX[7:0] to be configured by the VMM. Accesses to physical addresses above the specified value by the TD will cause the TDX module to inject a mostly correct #PF with the RSVD error code set. It has to deal with the same problems as allow_smaller_maxphyaddr for correctly setting the RSVD bit. I wasn’t thinking to push this feature for KVM due the movement away from allow_smaller_maxphyaddr and towards 0x80000008.EAX[23:16].
I would like to get your opinion of the MAXPA_VIRT feature of TDX. What is likely the KVM's decision on it? Won't support it due to it has the same limitation of allow_smaller_maxphyaddr?
