1 files changed, 44 insertions, 19 deletions

diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c
index cd7d90c9f644..92b95ae9a2ca 100644
--- a/virt/kvm/arm/arm.c
+++ b/virt/kvm/arm/arm.c
@@ -71,17 +71,17 @@ static DEFINE_PER_CPU(unsigned char, kvm_arm_hardware_enabled);
 
 static void kvm_arm_set_running_vcpu(struct kvm_vcpu *vcpu)
 {
-	BUG_ON(preemptible());
 	__this_cpu_write(kvm_arm_running_vcpu, vcpu);
 }
 
+DEFINE_STATIC_KEY_FALSE(userspace_irqchip_in_use);
+
 /**
  * kvm_arm_get_running_vcpu - get the vcpu running on the current CPU.
  * Must be called from non-preemptible context
  */
 struct kvm_vcpu *kvm_arm_get_running_vcpu(void)
 {
-	BUG_ON(preemptible());
 	return __this_cpu_read(kvm_arm_running_vcpu);
 }
 
@@ -295,6 +295,9 @@ void kvm_arch_vcpu_postcreate(struct kvm_vcpu *vcpu)
 
 void kvm_arch_vcpu_free(struct kvm_vcpu *vcpu)
 {
+	if (vcpu->arch.has_run_once && unlikely(!irqchip_in_kernel(vcpu->kvm)))
+		static_branch_dec(&userspace_irqchip_in_use);
+
 	kvm_mmu_free_memory_caches(vcpu);
 	kvm_timer_vcpu_terminate(vcpu);
 	kvm_pmu_vcpu_destroy(vcpu);
@@ -532,14 +535,22 @@ static int kvm_vcpu_first_run_init(struct kvm_vcpu *vcpu)
 
 	vcpu->arch.has_run_once = true;
 
-	/*
-	 * Map the VGIC hardware resources before running a vcpu the first
-	 * time on this VM.
-	 */
-	if (unlikely(irqchip_in_kernel(kvm) && !vgic_ready(kvm))) {
-		ret = kvm_vgic_map_resources(kvm);
-		if (ret)
-			return ret;
+	if (likely(irqchip_in_kernel(kvm))) {
+		/*
+		 * Map the VGIC hardware resources before running a vcpu the
+		 * first time on this VM.
+		 */
+		if (unlikely(!vgic_ready(kvm))) {
+			ret = kvm_vgic_map_resources(kvm);
+			if (ret)
+				return ret;
+		}
+	} else {
+		/*
+		 * Tell the rest of the code that there are userspace irqchip
+		 * VMs in the wild.
+		 */
+		static_branch_inc(&userspace_irqchip_in_use);
 	}
 
 	ret = kvm_timer_enable(vcpu);
@@ -680,19 +691,30 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
 		kvm_vgic_flush_hwstate(vcpu);
 
 		/*
-		 * If we have a singal pending, or need to notify a userspace
-		 * irqchip about timer or PMU level changes, then we exit (and
-		 * update the timer level state in kvm_timer_update_run
-		 * below).
+		 * Exit if we have a signal pending so that we can deliver the
+		 * signal to user space.
 		 */
-		if (signal_pending(current) ||
-		    kvm_timer_should_notify_user(vcpu) ||
-		    kvm_pmu_should_notify_user(vcpu)) {
+		if (signal_pending(current)) {
 			ret = -EINTR;
 			run->exit_reason = KVM_EXIT_INTR;
 		}
 
 		/*
+		 * If we're using a userspace irqchip, then check if we need
+		 * to tell a userspace irqchip about timer or PMU level
+		 * changes and if so, exit to userspace (the actual level
+		 * state gets updated in kvm_timer_update_run and
+		 * kvm_pmu_update_run below).
+		 */
+		if (static_branch_unlikely(&userspace_irqchip_in_use)) {
+			if (kvm_timer_should_notify_user(vcpu) ||
+			    kvm_pmu_should_notify_user(vcpu)) {
+				ret = -EINTR;
+				run->exit_reason = KVM_EXIT_INTR;
+			}
+		}
+
+		/*
 		 * Ensure we set mode to IN_GUEST_MODE after we disable
 		 * interrupts and before the final VCPU requests check.
 		 * See the comment in kvm_vcpu_exiting_guest_mode() and
@@ -704,7 +726,8 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
 		    kvm_request_pending(vcpu)) {
 			vcpu->mode = OUTSIDE_GUEST_MODE;
 			kvm_pmu_sync_hwstate(vcpu);
-			kvm_timer_sync_hwstate(vcpu);
+			if (static_branch_unlikely(&userspace_irqchip_in_use))
+				kvm_timer_sync_hwstate(vcpu);
 			kvm_vgic_sync_hwstate(vcpu);
 			local_irq_enable();
 			preempt_enable();
@@ -748,7 +771,8 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
 		 * we don't want vtimer interrupts to race with syncing the
 		 * timer virtual interrupt state.
 		 */
-		kvm_timer_sync_hwstate(vcpu);
+		if (static_branch_unlikely(&userspace_irqchip_in_use))
+			kvm_timer_sync_hwstate(vcpu);
 
 		/*
 		 * We may have taken a host interrupt in HYP mode (ie
@@ -1277,6 +1301,7 @@ static int hyp_init_cpu_pm_notifier(struct notifier_block *self,
 			cpu_hyp_reset();
 
 		return NOTIFY_OK;
+	case CPU_PM_ENTER_FAILED:
 	case CPU_PM_EXIT:
 		if (__this_cpu_read(kvm_arm_hardware_enabled))
 			/* The hardware was enabled before suspend. */