On 11/2/2023 5:37 PM, Nikunj A. Dadhania wrote: > On 11/2/2023 4:03 PM, Kirill A. Shutemov wrote: >> On Thu, Nov 02, 2023 at 11:23:34AM +0530, Nikunj A. Dadhania wrote: >>> 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. >> >> kvmclock lowers its rating if TSC is good enough: >> >> if (boot_cpu_has(X86_FEATURE_CONSTANT_TSC) && >> boot_cpu_has(X86_FEATURE_NONSTOP_TSC) && >> !check_tsc_unstable()) >> kvm_clock.rating = 299; >> >> Does your TSC meet the requirements? > > I have set TscInvariant (bit 8) in CPUID_8000_0007_edx and TSC is set as reliable. > > With this I see kvm_clock rating being lowered, but kvm-clock is still being picked as clock-source. Ah.. at later point TSC is picked up, is this expected ? [ 2.564052] clocksource: Switched to clocksource kvm-clock [ 2.678136] clocksource: Switched to clocksource tsc Regards Nikunj
