linux-kernel - Re: [PATCH 7/7] KVM: VMX: Handle NMI VM-Exits in noinstr region

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Message-ID: <Y8kSLBwUuqzlcSEZ@hirez.programming.kicks-ass.net>
Date:   Thu, 19 Jan 2023 10:49:32 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Sean Christopherson <seanjc@...gle.com>
Cc:     Paolo Bonzini <pbonzini@...hat.com>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, Andy Lutomirski <luto@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH 7/7] KVM: VMX: Handle NMI VM-Exits in noinstr region

On Tue, Dec 13, 2022 at 06:09:12AM +0000, Sean Christopherson wrote:

> @@ -7119,6 +7118,18 @@ static noinstr void vmx_vcpu_enter_exit(struct kvm_vcpu *vcpu,
>  
>  	vmx_enable_fb_clear(vmx);
>  
> +	if (unlikely(vmx->fail))
> +		vmx->exit_reason.full = 0xdead;
> +	else
> +		vmx->exit_reason.full = vmcs_read32(VM_EXIT_REASON);
> +
> +	if ((u16)vmx->exit_reason.basic == EXIT_REASON_EXCEPTION_NMI &&
> +	    is_nmi(vmx_get_intr_info(vcpu))) {
> +		kvm_before_interrupt(vcpu, KVM_HANDLING_NMI);
> +		vmx_do_nmi_irqoff();
> +		kvm_after_interrupt(vcpu);
> +	}
> +
>  	guest_state_exit_irqoff();
>  }

I think we're going to have to sprinkle __always_inline on the
kvm_{before,after}_interrupt() things (or I missed the earlier patches
doing this already), sometimes compilers are just weird.