Re: [PATCH v5 13/14] x86/tsc: Mark Secure TSC as reliable clocksource

Nikunj A. Dadhania
2023-11-02T05:53:52Z

On 10/30/2023 10:48 PM, Dave Hansen wrote:
> On 10/29/23 23:36, Nikunj A Dadhania wrote:
> ...
>> diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
>> index 15f97c0abc9d..b0a8546d3703 100644
>> --- a/arch/x86/kernel/tsc.c
>> +++ b/arch/x86/kernel/tsc.c
>> @@ -1241,7 +1241,7 @@ static void __init check_system_tsc_reliable(void)
>> tsc_clocksource_reliable = 1;
>> }
>> #endif
>> - if (boot_cpu_has(X86_FEATURE_TSC_RELIABLE))
>> + if (boot_cpu_has(X86_FEATURE_TSC_RELIABLE) || cc_platform_has(CC_ATTR_GUEST_SECURE_TSC))
>> tsc_clocksource_reliable = 1;
>
> Why can't you just set X86_FEATURE_TSC_RELIABLE?

Last time when I tried, I had removed my kvmclock changes and I had set the X86_FEATURE_TSC_RELIABLE similar to Kirill's patch[1], this did not select the SecureTSC.

Let me try setting X86_FEATURE_TSC_RELIABLE and retaining my patch for skipping kvmclock.

Regards
Nikunj

1: https://lore.kernel.org/lkml/20230808162320.27297-1-kirill.shutemov@linux.intel.com/