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. [ 0.000834] kvmclock_init: lowering kvm_clock rating [ 0.002623] clocksource: kvm-clock: mask: 0xffffffffffffffff max_cycles: 0x1cd42e4dffb, max_idle_ns: 881590591483 ns [ 2.295082] clocksource: Switched to clocksource kvm-clock Regards Nikunj
