KVM: correctly detect APIC SW state in kvm_apic_post_state_restore()

For apic_set_spiv() to track APIC SW state correctly it needs to see
previous and next values of the spurious vector register, but currently
memset() overwrite the old value before apic_set_spiv() get a chance to
do tracking. Fix it by calling apic_set_spiv() before overwriting old
value.
Signed-off-by: NGleb Natapov <gleb@redhat.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

arch/x86/kvm/lapic.c

@@ -1389,13 +1389,16 @@ int kvm_get_apic_interrupt(struct kvm_vcpu *vcpu)
 	return vector;
 }
 
-void kvm_apic_post_state_restore(struct kvm_vcpu *vcpu)
+void kvm_apic_post_state_restore(struct kvm_vcpu *vcpu,
+		struct kvm_lapic_state *s)
 {
 	struct kvm_lapic *apic = vcpu->arch.apic;
 
 	kvm_lapic_set_base(vcpu, vcpu->arch.apic_base);
+	/* set SPIV separately to get count of SW disabled APICs right */
+	apic_set_spiv(apic, *((u32 *)(s->regs + APIC_SPIV)));
+	memcpy(vcpu->arch.apic->regs, s->regs, sizeof *s);
 	kvm_apic_set_version(vcpu);
-	apic_set_spiv(apic, kvm_apic_get_reg(apic, APIC_SPIV));
 
 	apic_update_ppr(apic);
 	hrtimer_cancel(&apic->lapic_timer.timer);

arch/x86/kvm/lapic.h

@@ -54,7 +54,8 @@ int kvm_apic_local_deliver(struct kvm_lapic *apic, int lvt_type);
 
 u64 kvm_get_apic_base(struct kvm_vcpu *vcpu);
 void kvm_set_apic_base(struct kvm_vcpu *vcpu, u64 data);
-void kvm_apic_post_state_restore(struct kvm_vcpu *vcpu);
+void kvm_apic_post_state_restore(struct kvm_vcpu *vcpu,
+		struct kvm_lapic_state *s);
 int kvm_lapic_find_highest_irr(struct kvm_vcpu *vcpu);
 
 u64 kvm_get_lapic_tscdeadline_msr(struct kvm_vcpu *vcpu);

arch/x86/kvm/x86.c

@@ -2348,8 +2348,7 @@ static int kvm_vcpu_ioctl_get_lapic(struct kvm_vcpu *vcpu,
 static int kvm_vcpu_ioctl_set_lapic(struct kvm_vcpu *vcpu,
 				    struct kvm_lapic_state *s)
 {
-	memcpy(vcpu->arch.apic->regs, s->regs, sizeof *s);
-	kvm_apic_post_state_restore(vcpu);
+	kvm_apic_post_state_restore(vcpu, s);
 	update_cr8_intercept(vcpu);
 
 	return 0;