linux-kernel - [PATCH v4 08/15] KVM: x86: Deactivate APICv on vCPU with APIC disabled

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Date:   Sat, 7 May 2022 21:39:23 -0500
From:   Suravee Suthikulpanit <suravee.suthikulpanit@....com>
To:     <linux-kernel@...r.kernel.org>, <kvm@...r.kernel.org>
CC:     <pbonzini@...hat.com>, <mlevitsk@...hat.com>, <seanjc@...gle.com>,
        <joro@...tes.org>, <jon.grimm@....com>, <wei.huang2@....com>,
        <terry.bowman@....com>,
        Suravee Suthikulpanit <suravee.suthikulpanit@....com>
Subject: [PATCH v4 08/15] KVM: x86: Deactivate APICv on vCPU with APIC disabled

APICv should be deactivated on vCPU that has APIC disabled.
Therefore, call kvm_vcpu_update_apicv() when changing
APIC mode, and add additional check for APIC disable mode
when determine APICV activation,

Suggested-by: Maxim Levitsky <mlevitsk@...hat.com>
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@....com>
---
 arch/x86/kvm/lapic.c | 4 +++-
 arch/x86/kvm/x86.c   | 4 +++-
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 8b8c4a905976..680824d7aa0d 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -2346,8 +2346,10 @@ void kvm_lapic_set_base(struct kvm_vcpu *vcpu, u64 value)
 	if (((old_value ^ value) & X2APIC_ENABLE) && (value & X2APIC_ENABLE))
 		kvm_apic_set_x2apic_id(apic, vcpu->vcpu_id);
 
-	if ((old_value ^ value) & (MSR_IA32_APICBASE_ENABLE | X2APIC_ENABLE))
+	if ((old_value ^ value) & (MSR_IA32_APICBASE_ENABLE | X2APIC_ENABLE)) {
+		kvm_vcpu_update_apicv(vcpu);
 		static_call_cond(kvm_x86_set_virtual_apic_mode)(vcpu);
+	}
 
 	apic->base_address = apic->vcpu->arch.apic_base &
 			     MSR_IA32_APICBASE_BASE;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 8ee8c91fa762..77e49892dea1 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -9836,7 +9836,9 @@ void kvm_vcpu_update_apicv(struct kvm_vcpu *vcpu)
 
 	down_read(&vcpu->kvm->arch.apicv_update_lock);
 
-	activate = kvm_vcpu_apicv_activated(vcpu);
+	/* Do not activate APICV when APIC is disabled */
+	activate = kvm_vcpu_apicv_activated(vcpu) &&
+		   (kvm_get_apic_mode(vcpu) != LAPIC_MODE_DISABLED);
 
 	if (vcpu->arch.apicv_active == activate)
 		goto out;
-- 
2.25.1