Re: [PATCH v5 04/11] target/i386/kvm: Only save/load kvmclock MSRs when kvmclock enabled

Zhao Liu
2024-12-25T03:29:56Z

On Tue, Dec 24, 2024 at 04:31:28PM +0100, Paolo Bonzini wrote:
> Date: Tue, 24 Dec 2024 16:31:28 +0100
> From: Paolo Bonzini <pbonzini@redhat.com>
> Subject: Re: [PATCH v5 04/11] target/i386/kvm: Only save/load kvmclock MSRs
> when kvmclock enabled
>
> On 11/6/24 04:07, Zhao Liu wrote:
> > MSR_KVM_SYSTEM_TIME and MSR_KVM_WALL_CLOCK are attached with the (old)
> > kvmclock feature (KVM_FEATURE_CLOCKSOURCE).
> >
> > So, just save/load them only when kvmclock (KVM_FEATURE_CLOCKSOURCE) is
> > enabled.
> >
> > Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
> >
>
> The MSRs contains the same values as the "new" pair; QEMU only has to
> save/restore one of them but the code should be active for both feature bits
> and thus use
>
> + if (env->env.features[FEAT_KVM] & (CPUID_KVM_CLOCK |
> + CPUID_KVM_CLOCK2)) {
>

This is the correct way, thanks.

Regards,
Zhao