KVM: lapic: Refactor ->set_hv_timer to use an explicit expired param

Refactor kvm_x86_ops->set_hv_timer to use an explicit parameter for
stating that the timer has expired.  Overloading the return value is
unnecessarily clever, e.g. can lead to confusion over the proper return
value from start_hv_timer() when r==1.

Cc: Wanpeng Li <wanpengli@tencent.com>
Cc: Liran Alon <liran.alon@oracle.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/include/asm/kvm_host.h

@@ -1168,7 +1168,8 @@ struct kvm_x86_ops {
 			      uint32_t guest_irq, bool set);
 	void (*apicv_post_state_restore)(struct kvm_vcpu *vcpu);
 
-	int (*set_hv_timer)(struct kvm_vcpu *vcpu, u64 guest_deadline_tsc);
+	int (*set_hv_timer)(struct kvm_vcpu *vcpu, u64 guest_deadline_tsc,
+			    bool *expired);
 	void (*cancel_hv_timer)(struct kvm_vcpu *vcpu);
 
 	void (*setup_mce)(struct kvm_vcpu *vcpu);

arch/x86/kvm/lapic.c

@@ -1673,7 +1673,8 @@ static void cancel_hv_timer(struct kvm_lapic *apic)
 static bool start_hv_timer(struct kvm_lapic *apic)
 {
 	struct kvm_timer *ktimer = &apic->lapic_timer;
-	int r;
+	struct kvm_vcpu *vcpu = apic->vcpu;
+	bool expired;
 
 	WARN_ON(preemptible());
 	if (!kvm_x86_ops->set_hv_timer)
@@ -1685,8 +1686,7 @@ static bool start_hv_timer(struct kvm_lapic *apic)
 	if (!ktimer->tscdeadline)
 		return false;
 
-	r = kvm_x86_ops->set_hv_timer(apic->vcpu, ktimer->tscdeadline);
-	if (r < 0)
+	if (kvm_x86_ops->set_hv_timer(vcpu, ktimer->tscdeadline, &expired))
 		return false;
 
 	ktimer->hv_timer_in_use = true;
@@ -1704,13 +1704,13 @@ static bool start_hv_timer(struct kvm_lapic *apic)
 		 */
 		if (atomic_read(&ktimer->pending)) {
 			cancel_hv_timer(apic);
-		} else if (r) {
+		} else if (expired) {
 			apic_timer_expired(apic);
 			cancel_hv_timer(apic);
 		}
 	}
 
-	trace_kvm_hv_timer_state(apic->vcpu->vcpu_id, ktimer->hv_timer_in_use);
+	trace_kvm_hv_timer_state(vcpu->vcpu_id, ktimer->hv_timer_in_use);
 
 	return true;
 }

arch/x86/kvm/vmx/vmx.c

@@ -7041,7 +7041,8 @@ static inline int u64_shl_div_u64(u64 a, unsigned int shift,
 	return 0;
 }
 
-static int vmx_set_hv_timer(struct kvm_vcpu *vcpu, u64 guest_deadline_tsc)
+static int vmx_set_hv_timer(struct kvm_vcpu *vcpu, u64 guest_deadline_tsc,
+			    bool *expired)
 {
 	struct vcpu_vmx *vmx;
 	u64 tscl, guest_tscl, delta_tsc, lapic_timer_advance_cycles;
@@ -7078,7 +7079,8 @@ static int vmx_set_hv_timer(struct kvm_vcpu *vcpu, u64 guest_deadline_tsc)
 		return -ERANGE;
 
 	vmx->hv_deadline_tsc = tscl + delta_tsc;
-	return delta_tsc == 0;
+	*expired = !delta_tsc;
+	return 0;
 }
 
 static void vmx_cancel_hv_timer(struct kvm_vcpu *vcpu)