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

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Message-ID: <20190122102450.125349-1-Suravee.Suthikulpanit@amd.com>
Date:   Tue, 22 Jan 2019 10:25:13 +0000
From:   "Suthikulpanit, Suravee" <Suravee.Suthikulpanit@....com>
To:     "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>,
        "pbonzini@...hat.com" <pbonzini@...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>,
        "Suthikulpanit, Suravee" <Suravee.Suthikulpanit@....com>
Subject: [PATCH] svm: Fix AVIC incomplete IPI emulation

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:
-- 
2.17.1