For AMD SNP guests with SecureTSC enabled, kvm-clock is being picked up
momentarily instead of selecting more stable TSC clocksource.
[ 0.000000] kvm-clock: Using msrs 4b564d01 and 4b564d00
[ 0.000001] kvm-clock: using sched offset of 1799357702246960 cycles
[ 0.001493] clocksource: kvm-clock: mask: 0xffffffffffffffff max_cycles: 0x1cd42e4dffb, max_idle_ns: 881590591483 ns
[ 0.006289] tsc: Detected 1996.249 MHz processor
[ 0.305123] clocksource: tsc-early: mask: 0xffffffffffffffff max_cycles: 0x398cadd9d93, max_idle_ns: 881590552906 ns
[ 1.045759] clocksource: Switched to clocksource kvm-clock
[ 1.141326] clocksource: tsc: mask: 0xffffffffffffffff max_cycles: 0x398cadd9d93, max_idle_ns: 881590552906 ns
[ 1.144634] clocksource: Switched to clocksource tsc
When Secure TSC is enabled, skip using the kvmclock. The guest kernel will
fallback and use Secure TSC based clocksource.
Signed-off-by: Nikunj A Dadhania <nikunj@xxxxxxx>
Tested-by: Peter Gonda <pgonda@xxxxxxxxxx>
---
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 5b2c15214a6b..3d03b4c937b9 100644
--- a/arch/x86/kernel/kvmclock.c
+++ b/arch/x86/kernel/kvmclock.c
@@ -289,7 +289,7 @@ 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))
return;
if (kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE2)) {
--
2.34.1
