linux-kernel - [RFCv2 PATCH 09/12] KVM: SVM: Refresh AVIC settings when changing APIC mode

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Date:   Tue, 8 Mar 2022 10:39:23 -0600
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: [RFCv2 PATCH 09/12] KVM: SVM: Refresh AVIC settings when changing APIC mode

When APIC mode is updated (e.g. from xAPIC to x2APIC),
KVM needs to update AVIC settings accordingly, whic is
handled by svm_refresh_apicv_exec_ctrl().

Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@....com>
---
 arch/x86/kvm/svm/avic.c | 19 ++++++++++++++++++-
 1 file changed, 18 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c
index 7e5a39a8e698..53559b8dfa52 100644
--- a/arch/x86/kvm/svm/avic.c
+++ b/arch/x86/kvm/svm/avic.c
@@ -625,7 +625,24 @@ void avic_post_state_restore(struct kvm_vcpu *vcpu)
 
 void svm_set_virtual_apic_mode(struct kvm_vcpu *vcpu)
 {
-	return;
+	struct vcpu_svm *svm = to_svm(vcpu);
+
+	if (!lapic_in_kernel(vcpu) || (avic_mode == AVIC_MODE_NONE))
+		return;
+
+	if (kvm_get_apic_mode(vcpu) == LAPIC_MODE_INVALID)
+		WARN_ONCE(true, "Invalid local APIC state");
+
+	svm->vmcb->control.avic_vapic_bar = svm->vcpu.arch.apic_base &
+					    VMCB_AVIC_APIC_BAR_MASK;
+	kvm_vcpu_update_apicv(&svm->vcpu);
+
+	/*
+	 * The VM could be running w/ AVIC activated switching from APIC
+	 * to x2APIC mode. We need to all refresh to make sure that all
+	 * x2AVIC configuration are being done.
+	 */
+	svm_refresh_apicv_exec_ctrl(&svm->vcpu);
 }
 
 void svm_hwapic_irr_update(struct kvm_vcpu *vcpu, int max_irr)
-- 
2.25.1