linux-kernel - [PATCH] KVM: x86: fix vcpu initialization with userspace lapic

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Date:   Thu,  1 Mar 2018 15:24:25 +0100
From:   Radim Krčmář <rkrcmar@...hat.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Dmitry Vyukov <dvyukov@...gle.com>, stable@...r.kernel.org
Subject: [PATCH] KVM: x86: fix vcpu initialization with userspace lapic

Moving the code around broke this rare configuration.
Use this opportunity to finally call lapic reset from vcpu reset.

Reported-by: Dmitry Vyukov <dvyukov@...gle.com>
Suggested-by: Paolo Bonzini <pbonzini@...hat.com>
Fixes: 0b2e9904c159 ("KVM: x86: move LAPIC initialization after VMCS creation")
Cc: stable@...r.kernel.org
Signed-off-by: Radim Krčmář <rkrcmar@...hat.com>
---
 arch/x86/kvm/lapic.c | 10 ++++------
 arch/x86/kvm/x86.c   |  3 ++-
 2 files changed, 6 insertions(+), 7 deletions(-)

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index cc5fe7a50dde..391dda8d43b7 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -2002,14 +2002,13 @@ void kvm_lapic_set_base(struct kvm_vcpu *vcpu, u64 value)
 
 void kvm_lapic_reset(struct kvm_vcpu *vcpu, bool init_event)
 {
-	struct kvm_lapic *apic;
+	struct kvm_lapic *apic = vcpu->arch.apic;
 	int i;
 
-	apic_debug("%s\n", __func__);
+	if (!apic)
+		return;
 
-	ASSERT(vcpu);
-	apic = vcpu->arch.apic;
-	ASSERT(apic != NULL);
+	apic_debug("%s\n", __func__);
 
 	/* Stop the timer in case it's a reset to an active apic */
 	hrtimer_cancel(&apic->lapic_timer.timer);
@@ -2568,7 +2567,6 @@ void kvm_apic_accept_events(struct kvm_vcpu *vcpu)
 
 	pe = xchg(&apic->pending_events, 0);
 	if (test_bit(KVM_APIC_INIT, &pe)) {
-		kvm_lapic_reset(vcpu, true);
 		kvm_vcpu_reset(vcpu, true);
 		if (kvm_vcpu_is_bsp(apic->vcpu))
 			vcpu->arch.mp_state = KVM_MP_STATE_RUNNABLE;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 1a3ed81031f1..3f96b51d0495 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -8123,7 +8123,6 @@ int kvm_arch_vcpu_setup(struct kvm_vcpu *vcpu)
 	kvm_vcpu_mtrr_init(vcpu);
 	vcpu_load(vcpu);
 	kvm_vcpu_reset(vcpu, false);
-	kvm_lapic_reset(vcpu, false);
 	kvm_mmu_setup(vcpu);
 	vcpu_put(vcpu);
 	return 0;
@@ -8166,6 +8165,8 @@ void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu)
 
 void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
 {
+	kvm_lapic_reset(vcpu, init_event);
+
 	vcpu->arch.hflags = 0;
 
 	vcpu->arch.smi_pending = 0;
-- 
2.15.1