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Reply-To: Sean Christopherson <seanjc@google.com>
Date:   Fri,  6 Jan 2023 01:12:36 +0000
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Message-ID: <20230106011306.85230-4-seanjc@google.com>
Subject: [PATCH v5 03/33] KVM: SVM: Flush the "current" TLB when activating AVIC
From:   Sean Christopherson <seanjc@google.com>
To:     Sean Christopherson <seanjc@google.com>,
        Paolo Bonzini <pbonzini@redhat.com>
Cc:     kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
        Alejandro Jimenez <alejandro.j.jimenez@oracle.com>,
        Maxim Levitsky <mlevitsk@redhat.com>,
        Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>,
        Li RongQing <lirongqing@baidu.com>,
        Greg Edwards <gedwards@ddn.com>
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Precedence: bulk

Flush the TLB when activating AVIC as the CPU can insert into the TLB
while AVIC is "locally" disabled.  KVM doesn't treat "APIC hardware
disabled" as VM-wide AVIC inhibition, and so when a vCPU has its APIC
hardware disabled, AVIC is not guaranteed to be inhibited.  As a result,
KVM may create a valid NPT mapping for the APIC base, which the CPU can
cache as a non-AVIC translation.

Note, Intel handles this in vmx_set_virtual_apic_mode().

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 arch/x86/kvm/svm/avic.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c
index 6919dee69f18..712330b80891 100644
--- a/arch/x86/kvm/svm/avic.c
+++ b/arch/x86/kvm/svm/avic.c
@@ -86,6 +86,12 @@ static void avic_activate_vmcb(struct vcpu_svm *svm)
 		/* Disabling MSR intercept for x2APIC registers */
 		svm_set_x2apic_msr_interception(svm, false);
 	} else {
+		/*
+		 * Flush the TLB, the guest may have inserted a non-APIC
+		 * mapping into the TLB while AVIC was disabled.
+		 */
+		kvm_make_request(KVM_REQ_TLB_FLUSH_CURRENT, &svm->vcpu);
+
 		/* For xAVIC and hybrid-xAVIC modes */
 		vmcb->control.avic_physical_id |= AVIC_MAX_PHYSICAL_ID;
 		/* Enabling MSR intercept for x2APIC registers */
-- 
2.39.0.314.g84b9a713c41-goog