linux-kernel - Re: [PATCH RESEND 3/3] KVM: SVM: Reenable handle_fastpath_set_msr_irqoff() after complete

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Date:   Mon, 14 Sep 2020 08:48:56 -0700
From:   Sean Christopherson <sean.j.christopherson@...el.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Wanpeng Li <kernellwp@...il.com>, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org, Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>,
        "Paul K ." <kronenpj@...nenpj.dyndns.org>
Subject: Re: [PATCH RESEND 3/3] KVM: SVM: Reenable
 handle_fastpath_set_msr_irqoff() after complete_interrupts()

On Sat, Sep 12, 2020 at 08:15:46AM +0200, Paolo Bonzini wrote:
> The overall patch is fairly simple:
> 
> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
> index 03dd7bac8034..d6ce75e107c0 100644
> --- a/arch/x86/kvm/svm/svm.c
> +++ b/arch/x86/kvm/svm/svm.c
> @@ -2938,8 +2938,6 @@ static int handle_exit(struct kvm_vcpu *vcpu,
> fastpath_t exit_fastpath)
>  	if (npt_enabled)
>  		vcpu->arch.cr3 = svm->vmcb->save.cr3;
> 
> -	svm_complete_interrupts(svm);
> -
>  	if (is_guest_mode(vcpu)) {
>  		int vmexit;
> 
> @@ -3504,7 +3502,6 @@ static __no_kcsan fastpath_t svm_vcpu_run(struct
> kvm_vcpu *vcpu)
>  	stgi();
> 
>  	/* Any pending NMI will happen here */
> -	exit_fastpath = svm_exit_handlers_fastpath(vcpu);
> 
>  	if (unlikely(svm->vmcb->control.exit_code == SVM_EXIT_NMI))
>  		kvm_after_interrupt(&svm->vcpu);
> @@ -3537,6 +3534,9 @@ static __no_kcsan fastpath_t svm_vcpu_run(struct
> kvm_vcpu *vcpu)
>  		     SVM_EXIT_EXCP_BASE + MC_VECTOR))
>  		svm_handle_mce(svm);
> 
> +	svm_complete_interrupts(svm);
> +	exit_fastpath = svm_exit_handlers_fastpath(vcpu);
> +
>  	vmcb_mark_all_clean(svm->vmcb);
>  	return exit_fastpath;
>  }
> 
> so I will just squash everything.

The thought behind the multi-patch series was to allow automatically applying
the fix to the 5.8 stable tree without having to take on the risk of moving
svm_complete_interrupts().