Re: [PATCH v4 26/47] x86/kvm: Don't disable kvmclock on BSP in syscore_suspend()

[Sean Christopherson <seanjc@google.com>]

On Sat, May 30, 2026, sashiko-bot@kernel.org wrote:
> > diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
> > index c81a24d0efdf6..fd1c417b4f9b9 100644
> > --- a/arch/x86/kernel/kvm.c
> > +++ b/arch/x86/kernel/kvm.c
> > @@ -460,7 +460,7 @@ static void __init sev_map_percpu_data(void)
> 
> [ ... ]
> 
> > -static void kvm_guest_cpu_offline(bool shutdown)
> > +static void kvm_guest_cpu_offline(enum kvm_guest_cpu_action action)
> >  {
> >  	kvm_disable_steal_time();
> >  	if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
> > @@ -468,9 +468,10 @@ static void kvm_guest_cpu_offline(bool shutdown)
> >  	if (kvm_para_has_feature(KVM_FEATURE_MIGRATION_CONTROL))
> >  		wrmsrq(MSR_KVM_MIGRATION_CONTROL, 0);
> 
> [Severity: High]
> This isn't a bug introduced by this patch, but I noticed that
> MSR_KVM_MIGRATION_CONTROL is cleared to 0 here during CPU offline and system
> suspend, but it does not appear to be re-enabled upon online/resume.
> 
> Since this patch introduces the kvm_guest_cpu_action enum to solve an
> identical state-machine issue for kvmclock, should we also use this action
> enum to ensure the migration control MSR isn't incorrectly cleared on
> suspend? Otherwise, wouldn't a single CPU hotplug event or a suspend/resume
> cycle permanently disable live migration for the entire VM?

Looks like.  That's someone else's future problem though.