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>> + WARN_ONCE(1, "For Secure TSC guest, changing the clocksource is not allowed!\n"); > > So this thing is trying to state that changing the clocksource is not allowed > but it still allows it. Why not simply do this: > > diff --git a/arch/x86/kernel/kvmclock.c b/arch/x86/kernel/kvmclock.c > index 960260a8d884..d8fef3a65a35 100644 > --- a/arch/x86/kernel/kvmclock.c > +++ b/arch/x86/kernel/kvmclock.c > @@ -151,14 +151,10 @@ bool kvm_check_and_clear_guest_paused(void) > > static int kvm_cs_enable(struct clocksource *cs) > { > - /* > - * TSC clocksource should be used for a guest with Secure TSC enabled, > - * taint the kernel and warn when the user changes the clocksource to > - * kvm-clock. > - */ > + /* Only the TSC should be used in a Secure TSC guest. */ > if (cc_platform_has(CC_ATTR_GUEST_SNP_SECURE_TSC)) { > - add_taint(TAINT_WARN, LOCKDEP_STILL_OK); > - WARN_ONCE(1, "For Secure TSC guest, changing the clocksource is not allowed!\n"); > + WARN_ONCE(1, "Secure TSC guest, changing the clocksource is not allowed!\n"); > + return 1; > } > > vclocks_set_used(VDSO_CLOCKMODE_PVCLOCK); > > ? Works as expected: $ echo 'kvm-clock' > /sys/devices/system/clocksource/clocksource0/current_clocksource [ 30.333603] ------------[ cut here ]------------ [ 30.334802] Secure TSC guest, changing the clocksource is not allowed! [ 30.336460] WARNING: CPU: 0 PID: 19 at arch/x86/kernel/kvmclock.c:156 kvm_cs_enable+0x57/0x70 Regards Nikunj