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Date:   Thu, 14 Jul 2022 18:23:57 +0000
From:   Sean Christopherson <seanjc@google.com>
To:     Peter Xu <peterx@redhat.com>
Cc:     Paolo Bonzini <pbonzini@redhat.com>,
        Vitaly Kuznetsov <vkuznets@redhat.com>,
        Wanpeng Li <wanpengli@tencent.com>,
        Jim Mattson <jmattson@google.com>,
        Joerg Roedel <joro@8bytes.org>, kvm@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/4] KVM: x86/mmu: Defer "full" MMU setup until after
 vendor hardware_setup()
Message-ID: <YtBfPU4lhPbuDJ3y@google.com>
References: <20220624232735.3090056-1-seanjc@google.com>
 <20220624232735.3090056-3-seanjc@google.com>
 <Ys3uDJ90dBeFFbka@xz-m1.local>
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On Tue, Jul 12, 2022, Peter Xu wrote:
> On Fri, Jun 24, 2022 at 11:27:33PM +0000, Sean Christopherson wrote:
> > @@ -11937,6 +11932,10 @@ int kvm_arch_hardware_setup(void *opaque)
> >  
> >  	kvm_ops_update(ops);
> >  
> > +	r = kvm_mmu_hardware_setup();
> > +	if (r)
> > +		goto out_unsetup;
> > +
> >  	kvm_register_perf_callbacks(ops->handle_intel_pt_intr);
> >  
> >  	if (!kvm_cpu_cap_has(X86_FEATURE_XSAVES))
> > @@ -11960,12 +11959,18 @@ int kvm_arch_hardware_setup(void *opaque)
> >  	kvm_caps.default_tsc_scaling_ratio = 1ULL << kvm_caps.tsc_scaling_ratio_frac_bits;
> >  	kvm_init_msr_list();
> >  	return 0;
> > +
> > +out_unsetup:
> > +	static_call(kvm_x86_hardware_unsetup)();
> 
> Should this be kvm_mmu_hardware_unsetup()?  Or did I miss something?..

There is no kvm_mmu_hardware_unsetup().  This path is called if kvm_mmu_hardware_setup()
fails, i.e. the common code doesn't need to unwind anything.

The vendor call is not shown in the patch diff, but it's before this as:

	r = ops->hardware_setup();
	if (r != 0)
		return r

there's no existing error paths after that runs, which is why the vendor unsetup
call is new.