linux-kernel - [PATCH 4/5] KVM: x86: remove unnecessary sync_pir_to

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Date:   Fri, 14 Oct 2016 20:21:30 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     rkrcmar@...hat.com, yang.zhang.wz@...il.com, feng.wu@...el.com,
        mst@...hat.com
Subject: [PATCH 4/5] KVM: x86: remove unnecessary sync_pir_to_irr

Synchronizing PIR to IRR is not needed in most callers of
apic_find_highest_irr.  Move it to the one place that matters,
interrupt acknowledgement.

Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
---
 arch/x86/kvm/lapic.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index c0928173b2e3..255b5e1658f6 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -382,8 +382,6 @@ static inline int apic_find_highest_irr(struct kvm_lapic *apic)
 	if (!apic->irr_pending)
 		return -1;
 
-	if (apic->vcpu->arch.apicv_active)
-		kvm_x86_ops->sync_pir_to_irr(apic->vcpu);
 	result = apic_search_irr(apic);
 	ASSERT(result == -1 || result >= 16);
 
@@ -1973,6 +1971,9 @@ int kvm_apic_has_interrupt(struct kvm_vcpu *vcpu)
 		return -1;
 
 	apic_update_ppr(apic);
+
+	if (apic->vcpu->arch.apicv_active)
+		kvm_x86_ops->sync_pir_to_irr(apic->vcpu);
 	highest_irr = apic_find_highest_irr(apic);
 	if ((highest_irr == -1) ||
 	    ((highest_irr & 0xF0) <= kvm_lapic_get_reg(apic, APIC_PROCPRI)))
@@ -2206,6 +2207,11 @@ void kvm_lapic_sync_to_vapic(struct kvm_vcpu *vcpu)
 	if (!test_bit(KVM_APIC_CHECK_VAPIC, &vcpu->arch.apic_attention))
 		return;
 
+	/* We don't get here when APICv is active, since that blocks
+	 * TPR access vmexits.
+	 */
+	WARN_ON_ONCE(vcpu->arch.apicv_active);
+
 	tpr = kvm_lapic_get_reg(apic, APIC_TASKPRI) & 0xff;
 	max_irr = apic_find_highest_irr(apic);
 	if (max_irr < 0)
-- 
1.8.3.1