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Reply-To: Sean Christopherson <seanjc@google.com>
Date:   Tue, 20 Sep 2022 23:31:29 +0000
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Message-ID: <20220920233134.940511-24-seanjc@google.com>
Subject: [PATCH v3 23/28] KVM: SVM: Always update local APIC on writes to
 logical dest register
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>,
        Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>,
        Maxim Levitsky <mlevitsk@redhat.com>,
        Li RongQing <lirongqing@baidu.com>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

Update the vCPU's local (virtual) APIC on LDR writes even if the write
"fails".  The APIC needs to recalc the optimized logical map even if the
LDR is invalid or zero, e.g. if the guest clears its LDR, the optimized
map will be left as is and the vCPU will receive interrupts using its
old LDR.

Fixes: 18f40c53e10f ("svm: Add VMEXIT handlers for AVIC")
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 arch/x86/kvm/svm/avic.c | 11 ++++-------
 1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c
index 27d5abc15a91..2b640c73f447 100644
--- a/arch/x86/kvm/svm/avic.c
+++ b/arch/x86/kvm/svm/avic.c
@@ -573,7 +573,7 @@ static void avic_invalidate_logical_id_entry(struct kvm_vcpu *vcpu)
 		clear_bit(AVIC_LOGICAL_ID_ENTRY_VALID_BIT, (unsigned long *)entry);
 }
 
-static int avic_handle_ldr_update(struct kvm_vcpu *vcpu)
+static void avic_handle_ldr_update(struct kvm_vcpu *vcpu)
 {
 	int ret = 0;
 	struct vcpu_svm *svm = to_svm(vcpu);
@@ -582,10 +582,10 @@ static int avic_handle_ldr_update(struct kvm_vcpu *vcpu)
 
 	/* AVIC does not support LDR update for x2APIC */
 	if (apic_x2apic_mode(vcpu->arch.apic))
-		return 0;
+		return;
 
 	if (ldr == svm->ldr_reg)
-		return 0;
+		return;
 
 	avic_invalidate_logical_id_entry(vcpu);
 
@@ -594,8 +594,6 @@ static int avic_handle_ldr_update(struct kvm_vcpu *vcpu)
 
 	if (!ret)
 		svm->ldr_reg = ldr;
-
-	return ret;
 }
 
 static void avic_handle_dfr_update(struct kvm_vcpu *vcpu)
@@ -617,8 +615,7 @@ static int avic_unaccel_trap_write(struct kvm_vcpu *vcpu)
 
 	switch (offset) {
 	case APIC_LDR:
-		if (avic_handle_ldr_update(vcpu))
-			return 0;
+		avic_handle_ldr_update(vcpu);
 		break;
 	case APIC_DFR:
 		avic_handle_dfr_update(vcpu);
-- 
2.37.3.968.ga6b4b080e4-goog