Re: [PATCH v2 6/7] KVM: X86: Move kvm_x86_ops.update_vcpu_model() into kvm_update_vcpu_model()

[Xiaoyao Li]

On 7/3/2020 2:59 AM, Sean Christopherson wrote:
> On Tue, Jun 23, 2020 at 07:58:15PM +0800, Xiaoyao Li wrote:
> > kvm_x86_ops.update_vcpu_model() is used to update vmx/svm vcpu settings
> > based on updated CPUID settings. So it's supposed to be called after
> > CPUIDs are fully updated, i.e., kvm_update_cpuid().
> >
> > Move it in kvm_update_vcpu_model().
>
> The changelog needs to provide an in-depth analysis of VMX and SVM to prove
> that there are no existing dependencies in the ordering.  I've done the
> analysis a few times over the past few years for a similar chage I carried
> in my SGX code, but dropped that code a while back and haven't done the
> analysis since.  Anyways, it should be documented.

No problem. Will add the analysis in next version.

> > Signed-off-by: Xiaoyao Li <xiaoyao.li@xxxxxxxxx>
> > ---
> > ---
> >   arch/x86/kvm/cpuid.c | 5 +++--
> >   1 file changed, 3 insertions(+), 2 deletions(-)
> >
> > diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
> > index d2f93823f9fd..5decc2dd5448 100644
> > --- a/arch/x86/kvm/cpuid.c
> > +++ b/arch/x86/kvm/cpuid.c
> > @@ -121,6 +121,8 @@ void kvm_update_vcpu_model(struct kvm_vcpu *vcpu)
> >   	struct kvm_lapic *apic = vcpu->arch.apic;
> >   	struct kvm_cpuid_entry2 *best;
> >   
> > +	kvm_x86_ops.update_vcpu_model(vcpu);
> > +
> >   	best = kvm_find_cpuid_entry(vcpu, 1, 0);
> >   	if (best && apic) {
> >   		if (cpuid_entry_has(best, X86_FEATURE_TSC_DEADLINE_TIMER))
> > @@ -136,6 +138,7 @@ void kvm_update_vcpu_model(struct kvm_vcpu *vcpu)
> >   		vcpu->arch.guest_supported_xcr0 =
> >   			(best->eax | ((u64)best->edx << 32)) & supported_xcr0;
> >   
> > +
>
> Spurious whitespace.
>
> >   	/* Note, maxphyaddr must be updated before tdp_level. */
> >   	vcpu->arch.maxphyaddr = cpuid_query_maxphyaddr(vcpu);
> >   	vcpu->arch.tdp_level = kvm_x86_ops.get_tdp_level(vcpu);
> > @@ -224,7 +227,6 @@ int kvm_vcpu_ioctl_set_cpuid(struct kvm_vcpu *vcpu,
> >   
> >   	cpuid_fix_nx_cap(vcpu);
> >   	kvm_apic_set_version(vcpu);
> > -	kvm_x86_ops.update_vcpu_model(vcpu);
> >   	kvm_update_cpuid(vcpu);
> >   	kvm_update_vcpu_model(vcpu);
> >   
> > @@ -254,7 +256,6 @@ int kvm_vcpu_ioctl_set_cpuid2(struct kvm_vcpu *vcpu,
> >   	}
> >   
> >   	kvm_apic_set_version(vcpu);
> > -	kvm_x86_ops.update_vcpu_model(vcpu);
> >   	kvm_update_cpuid(vcpu);
> >   	kvm_update_vcpu_model(vcpu);
> >   out:
> > --
> > 2.18.2