linux-kernel - [PATCH 4.20 64/88] svm: Fix AVIC incomplete IPI emulation

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Date:   Mon,  4 Mar 2019 09:22:47 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Suravee Suthikulpanit <suravee.suthikulpanit@....com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.20 64/88] svm: Fix AVIC incomplete IPI emulation

4.20-stable review patch.  If anyone has any objections, please let me know.

------------------

[ Upstream commit bb218fbcfaaa3b115d4cd7a43c0ca164f3a96e57 ]

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>
Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 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 13baba9d1cc1a..77a9481ce4c49 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -4486,25 +4486,14 @@ 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:
-- 
2.19.1