| Date | Mon, 30 Oct 2023 16:00:03 -0500 | Subject | Re: [PATCH v5 12/14] x86/kvmclock: Skip kvmclock when Secure TSC is available | From | Tom Lendacky <> |
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On 10/30/23 01:36, Nikunj A Dadhania wrote: > For AMD SNP guests having Secure TSC enabled, skip using the kvmclock. > The guest kernel will fallback and use Secure TSC based clocksource. > > Signed-off-by: Nikunj A Dadhania <nikunj@amd.com> > --- > arch/x86/kernel/kvmclock.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/x86/kernel/kvmclock.c b/arch/x86/kernel/kvmclock.c > index fb8f52149be9..779e7311fa6f 100644 > --- a/arch/x86/kernel/kvmclock.c > +++ b/arch/x86/kernel/kvmclock.c > @@ -288,7 +288,7 @@ void __init kvmclock_init(void) > { > u8 flags; > > - if (!kvm_para_available() || !kvmclock) > + if (!kvm_para_available() || !kvmclock || cc_platform_has(CC_ATTR_GUEST_SECURE_TSC))
And is setting X86_FEATURE_TSC_RELIABLE, as Dave Hansen suggests, enough to prevent usage of kvmclock?
There was a discussion here: https://lore.kernel.org/lkml/20230808162320.27297-1-kirill.shutemov@linux.intel.com/
Thanks, Tom
> return; > > if (kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE2)) {
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