linux-kernel - Re: [PATCH] svm: Fix AVIC incomplete IPI emulation

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Date:   Fri, 25 Jan 2019 18:51:49 +0100
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     "Suthikulpanit, Suravee" <Suravee.Suthikulpanit@....com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "x86@...nel.org" <x86@...nel.org>
Cc:     "joro@...tes.org" <joro@...tes.org>,
        "rkrcmar@...hat.com" <rkrcmar@...hat.com>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "bp@...en8.de" <bp@...en8.de>, "hpa@...or.com" <hpa@...or.com>
Subject: Re: [PATCH] svm: Fix AVIC incomplete IPI emulation

On 22/01/19 11:25, Suthikulpanit, Suravee wrote:
> From: Suravee Suthikulpanit <suravee.suthikulpanit@....com>
> 
> In case of incomplete IPI with invalid interrupt type, the current
> SVM driver does not properly emulate the IPI, and fails to boot
> FreeBSD guests with multiple vcpus when enabling AVIC.
> 
> Fix this by update APIC ICR high/low registers, which also
> emulate sending the IPI.
> 
> Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@....com>
> ---
>  arch/x86/kvm/svm.c | 19 ++++---------------
>  1 file changed, 4 insertions(+), 15 deletions(-)
> 
> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
> index 2aff835a65ed..8a0c9a1f6ac8 100644
> --- a/arch/x86/kvm/svm.c
> +++ b/arch/x86/kvm/svm.c
> @@ -4504,25 +4504,14 @@ static int avic_incomplete_ipi_interception(struct vcpu_svm *svm)
>  		kvm_lapic_reg_write(apic, APIC_ICR, icrl);
>  		break;
>  	case AVIC_IPI_FAILURE_TARGET_NOT_RUNNING: {
> -		int i;
> -		struct kvm_vcpu *vcpu;
> -		struct kvm *kvm = svm->vcpu.kvm;
>  		struct kvm_lapic *apic = svm->vcpu.arch.apic;
>  
>  		/*
> -		 * At this point, we expect that the AVIC HW has already
> -		 * set the appropriate IRR bits on the valid target
> -		 * vcpus. So, we just need to kick the appropriate vcpu.
> +		 * Update ICR high and low, then emulate sending IPI,
> +		 * which is handled when writing APIC_ICR.
>  		 */
> -		kvm_for_each_vcpu(i, vcpu, kvm) {
> -			bool m = kvm_apic_match_dest(vcpu, apic,
> -						     icrl & KVM_APIC_SHORT_MASK,
> -						     GET_APIC_DEST_FIELD(icrh),
> -						     icrl & KVM_APIC_DEST_MASK);
> -
> -			if (m && !avic_vcpu_is_running(vcpu))
> -				kvm_vcpu_wake_up(vcpu);
> -		}
> +		kvm_lapic_reg_write(apic, APIC_ICR2, icrh);
> +		kvm_lapic_reg_write(apic, APIC_ICR, icrl);
>  		break;
>  	}
>  	case AVIC_IPI_FAILURE_INVALID_TARGET:
> 

Queued, thanks.

Paolo