linux-kernel - Re: [PATCH RFC v7 03/64] KVM: SVM: Advertise private memory support to KVM

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Message-ID: <Y8hlwId/NlniGTe3@google.com>
Date:   Wed, 18 Jan 2023 21:33:52 +0000
From:   Sean Christopherson <seanjc@...gle.com>
To:     "Huang, Kai" <kai.huang@...el.com>
Cc:     "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "michael.roth@....com" <michael.roth@....com>,
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Subject: Re: [PATCH RFC v7 03/64] KVM: SVM: Advertise private memory support
 to KVM

On Wed, Jan 18, 2023, Huang, Kai wrote:
> On Wed, 2022-12-14 at 13:39 -0600, Michael Roth wrote:
> > diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
> > index 91352d692845..7f3e4d91c0c6 100644
> > --- a/arch/x86/kvm/svm/svm.c
> > +++ b/arch/x86/kvm/svm/svm.c
> > @@ -4694,6 +4694,14 @@ static int svm_vm_init(struct kvm *kvm)
> >  	return 0;
> >  }
> >  
> > +static int svm_private_mem_enabled(struct kvm *kvm)
> > +{
> > +	if (sev_guest(kvm))
> > +		return kvm->arch.upm_mode ? 1 : 0;
> > +
> > +	return IS_ENABLED(CONFIG_HAVE_KVM_PRIVATE_MEM_TESTING) ? 1 : 0;
> > +}
> > +
> 
> Is this new callback really needed?

Probably not.  For anything in this series that gets within spitting distance of
CONFIG_HAVE_KVM_PRIVATE_MEM_TESTING, my recommendation is to make a mental note
but otherwise ignore things like this for now.  I suspect it will be much, much
more efficient to sort all of this out when I smush UPM+SNP+TDX together in a few
weeks.