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: syzbot+fb7a33a4b6c35007a72b@syzkaller.appspotmail.com
Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Fixes: 0b2e9904c159 ("KVM: x86: move LAPIC initialization after VMCS creation")
Cc: stable@vger.kernel.org
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>

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 11649d290b93..18b5ca7a3197 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -8060,7 +8060,6 @@ 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;
@@ -8103,6 +8102,8 @@ 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;