linux-kernel - [PATCH] KVM: SVM: fix task switch emulation on INTn instruction.

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Message-Id: <20220714124453.188655-1-mlevitsk@redhat.com>
Date:   Thu, 14 Jul 2022 15:44:53 +0300
From:   Maxim Levitsky <mlevitsk@...hat.com>
To:     kvm@...r.kernel.org
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Joerg Roedel <joro@...tes.org>, Ingo Molnar <mingo@...hat.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org, Jim Mattson <jmattson@...gle.com>,
        "Maciej S. Szmigiero" <maciej.szmigiero@...cle.com>,
        Maxim Levitsky <mlevitsk@...hat.com>
Subject: [PATCH] KVM: SVM: fix task switch emulation on INTn instruction.

Recently KVM's SVM code switched to re-injecting software interrupt events,
if something prevented their delivery.

Task switch due to task gate in the IDT, however is an exception
to this rule, because in this case, INTn instruction causes
a task switch intercept and its emulation completes the INTn
emulation as well.

Add a missing case to task_switch_interception for that.

This fixes 32 bit kvm unit test taskswitch2.

Fixes: 7e5b5ef8dca322 ("KVM: SVM: Re-inject INTn instead of retrying the insn on "failure"")

Signed-off-by: Maxim Levitsky <mlevitsk@...hat.com>
---
 arch/x86/kvm/svm/svm.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 41bd7c5aa06a1e..638dd94f6e11f6 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -2399,6 +2399,7 @@ static int task_switch_interception(struct kvm_vcpu *vcpu)
 			kvm_clear_exception_queue(vcpu);
 			break;
 		case SVM_EXITINTINFO_TYPE_INTR:
+		case SVM_EXITINTINFO_TYPE_SOFT:
 			kvm_clear_interrupt_queue(vcpu);
 			break;
 		default:
-- 
2.34.3