On Thu, 2025-05-15 at 10:28 -0700, Rick Edgecombe wrote: > > I did a brief test on my SPR, where the host was not busy : > > tdh_mem_page_demote() was called 142 times, with each invocation taking > > around > > 10us. > > 10us doesn't seem too bad? Makes me think to not loop and instead just do a > single retry with interrupts disabled. We should definitely add the data based > reasoning to the log. > > The counter point is that the SEAMCALL must be supporting > TDX_INTERRUPTED_RESTARTABLE for a reason. And the reason probably is that it > sometimes takes longer than someone that was reasonable. Maybe we should ask > TDX > module folks if there is any history. Circling back here. After some research/discussion it seems demote should not take too long such that it should need the option to return TDX_INTERRUPTED_RESTARTABLE. Even in the dynamic PAMT case. The details of how to get this changed and documented are still ongoing, but for v2 I say we close this by expecting it to never return TDX_INTERRUPTED_RESTARTABLE. For now it can be a VM_BUG_ON() case, with the expectation that TDX module will update to make the logic valid. Sound good?
