Re: [PATCH v15 09/13] tsc: Use the GUEST_TSC_FREQ MSR for discovering TSC frequency

Borislav Petkov
2025-01-01T16:15:56Z

On Wed, Jan 01, 2025 at 02:26:04PM +0530, Nikunj A. Dadhania wrote:
> As kvm-clock would have set the callbacks, I need to point them to securetsc_get_tsc_khz().
>
> arch/x86/kernel/kvmclock.c: x86_platform.calibrate_tsc = kvm_get_tsc_khz;
> arch/x86/kernel/kvmclock.c: x86_platform.calibrate_cpu = kvm_get_tsc_khz;
>
> For virtualized environments, I see that all of them are assigning the same functions to different function ptrs.

So just because the others do it, you should do it too without even figuring
out *why*?

How about you do some git archeology and get to the actual reason why there
are two different function pointers and then analyze whether a secure TSC
guest can use the same function for both?

--
Regards/Gruss,
Boris.