linux-kernel - Re: [PATCH] KVM: x86: Unify cross-vCPU IBPB

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Message-ID: <Z-SCuESxIaOR0bCw@google.com>
Date: Wed, 26 Mar 2025 15:42:00 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Yosry Ahmed <yosry.ahmed@...ux.dev>
Cc: Paolo Bonzini <pbonzini@...hat.com>, Jim Mattson <jmattson@...gle.com>, x86@...nel.org, 
	kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] KVM: x86: Unify cross-vCPU IBPB

On Wed, Mar 26, 2025, Yosry Ahmed wrote:
> On Wed, Mar 26, 2025 at 01:46:04PM -0700, Sean Christopherson wrote:
> > > @@ -12367,10 +12381,13 @@ void kvm_arch_vcpu_postcreate(struct kvm_vcpu *vcpu)
> > >  
> > >  void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu)
> > >  {
> > > -	int idx;
> > > +	int idx, cpu;
> > >  
> > >  	kvmclock_reset(vcpu);
> > >  
> > > +	for_each_possible_cpu(cpu)
> > > +		cmpxchg(per_cpu_ptr(&last_vcpu, cpu), vcpu, NULL);
> > 
> > It's definitely worth keeping a version of SVM's comment to explaining the cross-CPU
> > nullification.
> 
> Good idea. Should I send a new version or will you take care of this as
> well while applying?

I'll fixup when applying.