linux-kernel - Re: [PATCH] KVM: VMX: Use accessor to read vmcs.INTR

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Message-ID: <20200427173241.GJ14870@linux.intel.com>
Date:   Mon, 27 Apr 2020 10:32:41 -0700
From:   Sean Christopherson <sean.j.christopherson@...el.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] KVM: VMX: Use accessor to read vmcs.INTR_INFO when
 handling exception

On Mon, Apr 27, 2020 at 07:28:02PM +0200, Paolo Bonzini wrote:
> On 27/04/20 19:18, Sean Christopherson wrote:
> > Use vmx_get_intr_info() when grabbing the cached vmcs.INTR_INFO in
> > handle_exception_nmi() to ensure the cache isn't stale.  Bypassing the
> > caching accessor doesn't cause any known issues as the cache is always
> > refreshed by handle_exception_nmi_irqoff(), but the whole point of
> > adding the proper caching mechanism was to avoid such dependencies.
> > 
> > Fixes: 8791585837f6 ("KVM: VMX: Cache vmcs.EXIT_INTR_INFO using arch avail_reg flags")
> > Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
> > ---
> >  arch/x86/kvm/vmx/vmx.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> > index 3ab6ca6062ce..7bddcb24f6f3 100644
> > --- a/arch/x86/kvm/vmx/vmx.c
> > +++ b/arch/x86/kvm/vmx/vmx.c
> > @@ -4677,7 +4677,7 @@ static int handle_exception_nmi(struct kvm_vcpu *vcpu)
> >  	u32 vect_info;
> >  
> >  	vect_info = vmx->idt_vectoring_info;
> > -	intr_info = vmx->exit_intr_info;
> > +	intr_info = vmx_get_intr_info(vcpu);
> >  
> >  	if (is_machine_check(intr_info) || is_nmi(intr_info))
> >  		return 1; /* handled by handle_exception_nmi_irqoff() */
> > 
> 
> Hasn't this been applied already?

No, I missed this case in the original patch, and the other fix was for
incorrect sizing of an exit_qual variable.