linux-kernel - [PATCH] svm: Fix improper check when deactivate AVIC

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Date:   Tue, 29 Jan 2019 08:09:46 +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 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>
Cc: Paolo Bonzini <pbonzini@...hat.com>
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@....com>
---
 arch/x86/kvm/svm.c | 22 ++++++++++++++++++----
 1 file changed, 18 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index d35c9002f282..59b1f68060c7 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -390,6 +390,8 @@ static int nested_svm_vmexit(struct vcpu_svm *svm);
 static int nested_svm_check_exception(struct vcpu_svm *svm, unsigned nr,
 				      bool has_error_code, u32 error_code);
 
+static bool svm_get_enable_apicv(struct kvm_vcpu *vcpu);
+
 enum {
 	VMCB_INTERCEPTS, /* Intercept vectors, TSC offset,
 			    pause filter count */
@@ -478,6 +480,12 @@ static inline struct vcpu_svm *to_svm(struct kvm_vcpu *vcpu)
 	return container_of(vcpu, struct vcpu_svm, vcpu);
 }
 
+static bool is_avic_active(struct vcpu_svm *svm)
+{
+	return (svm_get_enable_apicv(&svm->vcpu) &&
+		svm->vmcb->control.int_ctl & AVIC_ENABLE_MASK);
+}
+
 static inline void avic_update_vapic_bar(struct vcpu_svm *svm, u64 data)
 {
 	svm->vmcb->control.avic_vapic_bar = data & VMCB_AVIC_APIC_BAR_MASK;
@@ -5108,17 +5116,23 @@ static void svm_hwapic_isr_update(struct kvm_vcpu *vcpu, int max_isr)
 {
 }
 
-/* Note: Currently only used by Hyper-V. */
-static void svm_refresh_apicv_exec_ctrl(struct kvm_vcpu *vcpu)
+static void svm_deactivate_avic(struct kvm_vcpu *vcpu)
 {
 	struct vcpu_svm *svm = to_svm(vcpu);
 	struct vmcb *vmcb = svm->vmcb;
 
-	if (!kvm_vcpu_apicv_active(&svm->vcpu))
+	if (!lapic_in_kernel(vcpu) || !is_avic_active(svm))
 		return;
 
 	vmcb->control.int_ctl &= ~AVIC_ENABLE_MASK;
-	mark_dirty(vmcb, VMCB_INTR);
+	mark_dirty(vmcb, VMCB_AVIC);
+}
+
+/* Note: Currently only used by Hyper-V. */
+static void svm_refresh_apicv_exec_ctrl(struct kvm_vcpu *vcpu)
+{
+	if (!kvm_vcpu_apicv_active(vcpu))
+		svm_deactivate_avic(vcpu);
 }
 
 static void svm_load_eoi_exitmap(struct kvm_vcpu *vcpu, u64 *eoi_exit_bitmap)
-- 
2.17.1