On Thu, Jul 02, 2020 at 11:54:03AM -0700, Sean Christopherson wrote:
> On Tue, Jun 23, 2020 at 07:58:11PM +0800, Xiaoyao Li wrote:
> > As handling of bits other leaf 1 added over time, kvm_update_cpuid()
> > should not return directly if leaf 1 is absent, but should go on
> > updateing other CPUID leaves.
> >
> > Signed-off-by: Xiaoyao Li <xiaoyao.li@xxxxxxxxx>
>
> This should probably be marked for stable.
>
> > ---
> > arch/x86/kvm/cpuid.c | 23 +++++++++++------------
> > 1 file changed, 11 insertions(+), 12 deletions(-)
> >
> > diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
> > index 1d13bad42bf9..0164dac95ef5 100644
> > --- a/arch/x86/kvm/cpuid.c
> > +++ b/arch/x86/kvm/cpuid.c
> > @@ -60,22 +60,21 @@ int kvm_update_cpuid(struct kvm_vcpu *vcpu)
> > struct kvm_lapic *apic = vcpu->arch.apic;
> >
> > best = kvm_find_cpuid_entry(vcpu, 1, 0);
> > - if (!best)
> > - return 0;
>
> Rather than wrap the existing code, what about throwing it in a separate
> helper? That generates an easier to read diff and also has the nice
> property of getting 'apic' out of the common code.
Hrm, that'd be overkill once the apic code is moved in a few patches.
What if you keep the cpuid updates wrapped (as in this patch), but then
do
if (best && apic) {
}
for the apic path? That'll minimize churn for code that is disappearing,
e.g. will make future git archaeologists happy :-).
> > -
> > - /* Update OSXSAVE bit */
> > - if (boot_cpu_has(X86_FEATURE_XSAVE) && best->function == 0x1)
> > - cpuid_entry_change(best, X86_FEATURE_OSXSAVE,
> > + if (best) {
> > + /* Update OSXSAVE bit */
> > + if (boot_cpu_has(X86_FEATURE_XSAVE))
> > + cpuid_entry_change(best, X86_FEATURE_OSXSAVE,
> > kvm_read_cr4_bits(vcpu, X86_CR4_OSXSAVE));
> >
> > - cpuid_entry_change(best, X86_FEATURE_APIC,
> > + cpuid_entry_change(best, X86_FEATURE_APIC,
> > vcpu->arch.apic_base & MSR_IA32_APICBASE_ENABLE);
> >
> > - if (apic) {
> > - if (cpuid_entry_has(best, X86_FEATURE_TSC_DEADLINE_TIMER))
> > - apic->lapic_timer.timer_mode_mask = 3 << 17;
> > - else
> > - apic->lapic_timer.timer_mode_mask = 1 << 17;
> > + if (apic) {
> > + if (cpuid_entry_has(best, X86_FEATURE_TSC_DEADLINE_TIMER))
> > + apic->lapic_timer.timer_mode_mask = 3 << 17;
> > + else
> > + apic->lapic_timer.timer_mode_mask = 1 << 17;
> > + }
> > }
> >
> > best = kvm_find_cpuid_entry(vcpu, 7, 0);
> > --
> > 2.18.2
> >
