Re: [PATCH v2 00/25] TDX vCPU/VM creation

[Tony Lindgren]

On Thu, Oct 31, 2024 at 09:21:29PM +0200, Adrian Hunter wrote:
> On 30/10/24 21:00, Rick Edgecombe wrote:
> > Here is v2 of TDX VM/vCPU creation series. As discussed earlier, non-nits 
> > from v1[0] have been applied and it’s ready to hand off to Paolo. A few 
> > items remain that may be worth further discussion:
> >  - Disable CET/PT in tdx_get_supported_xfam(), as these features haven’t 
> >    been been tested.
> 
> It seems for Intel PT we have no support for restoring host
> state.  IA32_RTIT_* MSR preservation is Init(XFAM(8)) which means
> the TDX Module sets the MSR to its RESET value after TD Enty/Exit.
> So it seems to me XFAM(8) does need to be disabled until that is
> supported.

So for now, we should remove the PT bit from tdx_get_supported_xfam(),
but can still keep it in tdx_restore_host_xsave_state()?

Then for save/restore, maybe we can just use the pt_guest_enter() and
pt_guest_exit() also for TDX. Some additional checks are needed for
the pt_mode though as the TDX module always clears the state if PT is
enabled. And the PT_MODE_SYSTEM will be missing TDX enter/exit data
but might be otherwise usable.

Regards,

Tony