linux-kernel - Re: [PATCH 1/7] KVM: VMX: read idt_vectoring

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Date:   Wed, 17 Feb 2021 18:18:24 +0200
From:   Maxim Levitsky <mlevitsk@...hat.com>
To:     Paolo Bonzini <pbonzini@...hat.com>, kvm@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, Wanpeng Li <wanpengli@...cent.com>,
        Borislav Petkov <bp@...en8.de>, Joerg Roedel <joro@...tes.org>,
        Jim Mattson <jmattson@...gle.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Sean Christopherson <seanjc@...gle.com>,
        "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" <x86@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Ingo Molnar <mingo@...hat.com>
Subject: Re: [PATCH 1/7] KVM: VMX: read idt_vectoring_info a bit earlier

On Wed, 2021-02-17 at 17:06 +0100, Paolo Bonzini wrote:
> On 17/02/21 15:57, Maxim Levitsky wrote:
> > diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> > index b3e36dc3f164..e428d69e21c0 100644
> > --- a/arch/x86/kvm/vmx/vmx.c
> > +++ b/arch/x86/kvm/vmx/vmx.c
> > @@ -6921,13 +6921,15 @@ static fastpath_t vmx_vcpu_run(struct kvm_vcpu *vcpu)
> >  	if (unlikely((u16)vmx->exit_reason.basic == EXIT_REASON_MCE_DURING_VMENTRY))
> >  		kvm_machine_check();
> >  
> > +	if (likely(!vmx->exit_reason.failed_vmentry))
> > +		vmx->idt_vectoring_info = vmcs_read32(IDT_VECTORING_INFO_FIELD);
> > +
> 
> Any reason for the if?

Sean Christopherson asked me to do this to avoid updating idt_vectoring_info on failed
VM entry, to keep things as they were logically before this patch.

Best regards,
	Maxim Levitsky

> 
> Paolo
>