linux-kernel - [RFC PATCH 1/8] svm: Fix improper check when deactivate AVIC

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Date:   Mon, 4 Feb 2019 14:41:58 +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>,
        "jsteckli@...zon.de" <jsteckli@...zon.de>,
        "sironi@...zon.de" <sironi@...zon.de>,
        "wawei@...zon.de" <wawei@...zon.de>,
        "Suthikulpanit, Suravee" <Suravee.Suthikulpanit@....com>
Subject: [RFC PATCH 1/8] svm: Fix improper check when deactivate AVIC

The function svm_refresh_apicv_exec_ctrl() always returning prematurely
as kvm_vcpu_apicv_active() always return false when calling from
the function arch/x86/kvm/x86.c:kvm_vcpu_deactivate_apicv().
This is because the apicv_active is set to false just before calling
refresh_apicv_exec_ctrl().

Also, we need to mark VMCB_AVIC bit as dirty instead of VMCB_INTR.

So, fix svm_refresh_apicv_exec_ctrl() to properly deactivate AVIC.

Fixes: 67034bb9dd5e ('KVM: SVM: Add irqchip_split() checks before enabling AVIC')
Cc: Radim Krčmář <rkrcmar@...hat.com>
Suggested-by: Paolo Bonzini <pbonzini@...hat.com>
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@....com>
---
 arch/x86/kvm/svm.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index d35c9002f282..75508f665aef 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -5114,11 +5114,11 @@ static void svm_refresh_apicv_exec_ctrl(struct kvm_vcpu *vcpu)
 	struct vcpu_svm *svm = to_svm(vcpu);
 	struct vmcb *vmcb = svm->vmcb;
 
-	if (!kvm_vcpu_apicv_active(&svm->vcpu))
-		return;
-
-	vmcb->control.int_ctl &= ~AVIC_ENABLE_MASK;
-	mark_dirty(vmcb, VMCB_INTR);
+	if (kvm_vcpu_apicv_active(vcpu))
+		vmcb->control.int_ctl |= AVIC_ENABLE_MASK;
+	else
+		vmcb->control.int_ctl &= ~AVIC_ENABLE_MASK;
+	mark_dirty(vmcb, VMCB_AVIC);
 }
 
 static void svm_load_eoi_exitmap(struct kvm_vcpu *vcpu, u64 *eoi_exit_bitmap)
-- 
2.17.1