2 files changed, 28 insertions, 7 deletions

diff --git a/virt/kvm/async_pf.c b/virt/kvm/async_pf.c
index e033c79d52..28658b9e0d 100644
--- a/virt/kvm/async_pf.c
+++ b/virt/kvm/async_pf.c
@@ -87,7 +87,27 @@ static void async_pf_execute(struct work_struct *work)
 	__kvm_vcpu_wake_up(vcpu);
 
 	mmput(mm);
-	kvm_put_kvm(vcpu->kvm);
+}
+
+static void kvm_flush_and_free_async_pf_work(struct kvm_async_pf *work)
+{
+	/*
+	 * The async #PF is "done", but KVM must wait for the work item itself,
+	 * i.e. async_pf_execute(), to run to completion.  If KVM is a module,
+	 * KVM must ensure *no* code owned by the KVM (the module) can be run
+	 * after the last call to module_put().  Note, flushing the work item
+	 * is always required when the item is taken off the completion queue.
+	 * E.g. even if the vCPU handles the item in the "normal" path, the VM
+	 * could be terminated before async_pf_execute() completes.
+	 *
+	 * Wake all events skip the queue and go straight done, i.e. don't
+	 * need to be flushed (but sanity check that the work wasn't queued).
+	 */
+	if (work->wakeup_all)
+		WARN_ON_ONCE(work->work.func);
+	else
+		flush_work(&work->work);
+	kmem_cache_free(async_pf_cache, work);
 }
 
 void kvm_clear_async_pf_completion_queue(struct kvm_vcpu *vcpu)
@@ -114,7 +134,6 @@ void kvm_clear_async_pf_completion_queue(struct kvm_vcpu *vcpu)
 #else
 		if (cancel_work_sync(&work->work)) {
 			mmput(work->mm);
-			kvm_put_kvm(vcpu->kvm); /* == work->vcpu->kvm */
 			kmem_cache_free(async_pf_cache, work);
 		}
 #endif
@@ -126,7 +145,10 @@ void kvm_clear_async_pf_completion_queue(struct kvm_vcpu *vcpu)
 			list_first_entry(&vcpu->async_pf.done,
 					 typeof(*work), link);
 		list_del(&work->link);
-		kmem_cache_free(async_pf_cache, work);
+
+		spin_unlock(&vcpu->async_pf.lock);
+		kvm_flush_and_free_async_pf_work(work);
+		spin_lock(&vcpu->async_pf.lock);
 	}
 	spin_unlock(&vcpu->async_pf.lock);
 
@@ -151,7 +173,7 @@ void kvm_check_async_pf_completion(struct kvm_vcpu *vcpu)
 
 		list_del(&work->queue);
 		vcpu->async_pf.queued--;
-		kmem_cache_free(async_pf_cache, work);
+		kvm_flush_and_free_async_pf_work(work);
 	}
 }
 
@@ -186,7 +208,6 @@ bool kvm_setup_async_pf(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
 	work->arch = *arch;
 	work->mm = current->mm;
 	mmget(work->mm);
-	kvm_get_kvm(work->vcpu->kvm);
 
 	INIT_WORK(&work->work, async_pf_execute);
 
diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c
index 89912a17f5..c0e230f4c3 100644
--- a/virt/kvm/eventfd.c
+++ b/virt/kvm/eventfd.c
@@ -61,7 +61,7 @@ static void irqfd_resampler_notify(struct kvm_kernel_irqfd_resampler *resampler)
 
 	list_for_each_entry_srcu(irqfd, &resampler->list, resampler_link,
 				 srcu_read_lock_held(&resampler->kvm->irq_srcu))
-		eventfd_signal(irqfd->resamplefd, 1);
+		eventfd_signal(irqfd->resamplefd);
 }
 
 /*
@@ -786,7 +786,7 @@ ioeventfd_write(struct kvm_vcpu *vcpu, struct kvm_io_device *this, gpa_t addr,
 	if (!ioeventfd_in_range(p, addr, len, val))
 		return -EOPNOTSUPP;
 
-	eventfd_signal(p->eventfd, 1);
+	eventfd_signal(p->eventfd);
 	return 0;
 }