linux-kernel - [PATCH v2 07/13] KVM: x86: reset APIC ID when enabling LAPIC

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Date:	Thu,  7 Jul 2016 19:15:44 +0200
From:	Radim Krčmář <rkrcmar@...hat.com>
To:	linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:	Paolo Bonzini <pbonzini@...hat.com>,
	"Lan, Tianyu" <tianyu.lan@...el.com>,
	Igor Mammedov <imammedo@...hat.com>,
	Jan Kiszka <jan.kiszka@....de>, Peter Xu <peterx@...hat.com>
Subject: [PATCH v2 07/13] KVM: x86: reset APIC ID when enabling LAPIC

APIC ID should be set to the initial APIC ID when enabling LAPIC.
This only matters if the guest changes APIC ID.  No sane OS does that.

Signed-off-by: Radim Krčmář <rkrcmar@...hat.com>
---
 v2: new [Paolo]

 arch/x86/kvm/lapic.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 41089dbeeafc..0fce77fdbe91 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -1720,9 +1720,10 @@ void kvm_lapic_set_base(struct kvm_vcpu *vcpu, u64 value)
 
 	/* update jump label if enable bit changes */
 	if ((old_value ^ value) & MSR_IA32_APICBASE_ENABLE) {
-		if (value & MSR_IA32_APICBASE_ENABLE)
+		if (value & MSR_IA32_APICBASE_ENABLE) {
+			kvm_apic_set_xapic_id(apic, vcpu->vcpu_id);
 			static_key_slow_dec_deferred(&apic_hw_disabled);
-		else
+		} else
 			static_key_slow_inc(&apic_hw_disabled.key);
 		recalculate_apic_map(vcpu->kvm);
 	}
-- 
2.9.0