On 9/18/23 05:08, Huang, Kai wrote: > On Fri, 2023-09-15 at 10:50 -0700, Dave Hansen wrote: >> On 9/15/23 10:43, Edgecombe, Rick P wrote: >>> On Sat, 2023-08-26 at 00:14 +1200, Kai Huang wrote: >>>> There are two problems in terms of using kexec() to boot to a new >>>> kernel when the old kernel has enabled TDX: 1) Part of the memory >>>> pages are still TDX private pages; 2) There might be dirty >>>> cachelines associated with TDX private pages. >>> Does TDX support hibernate? >> No. >> >> There's a whole bunch of volatile state that's generated inside the CPU >> and never leaves the CPU, like the ephemeral key that protects TDX >> module memory. >> >> SGX, for instance, never even supported suspend, IIRC. Enclaves just >> die and have to be rebuilt. > > Right. AFAICT TDX cannot survive from S3 either. All TDX keys get lost when > system enters S3. However I don't think TDX can be rebuilt after resume like > SGX. Let me confirm with TDX guys on this. By "rebuilt" I mean all private data is totally destroyed and rebuilt from scratch. The SGX architecture provides zero help other than delivering a fault and saying: "whoops all your data is gone". > I think we can register syscore_ops->suspend for TDX, and refuse to suspend when > TDX is enabled. This covers hibernate case too. > > In terms of how to check "TDX is enabled", ideally it's better to check whether > TDX module is actually initialized, but the worst case is we can use > platform_tdx_enabled(). (I need to think more on this) *Ideally* the firmware would have a choke point where it could just tell the OS that it can't suspend rather than the OS having to figure it out.
