ANDROID: virt: geniezone: Refactoring irqfd to align with upstream v6

[Detail]
- remove register/unregister ack notifier
- remove spi setting
- remove resamplerfd
- remove resampler_link

Change-Id: I7c641ba16ebcba208592dc78337501014a832ddf
Signed-off-by: Yingshiuan Pan <yingshiuan.pan@mediatek.com>
Signed-off-by: Yi-De Wu <yi-de.wu@mediatek.com>
Bug: 301179926
Link: https://lore.kernel.org/all/20230919111210.19615-10-yi-de.wu@mediatek.com/

drivers/virt/geniezone/gzvm_irqfd.c

@@ -14,41 +14,11 @@ struct gzvm_irq_ack_notifier {
 	void (*irq_acked)(struct gzvm_irq_ack_notifier *ian);
 };
 
-/**
- * struct gzvm_kernel_irqfd_resampler - irqfd resampler descriptor.
- * @gzvm: Poiner to gzvm.
- * @list: List of resampling struct _irqfd objects sharing this gsi.
- *		    RCU list modified under gzvm->irqfds.resampler_lock.
- * @notifier: gzvm irq ack notifier.
- * @link: Entry in list of gzvm->irqfd.resampler_list.
- *		    Use for sharing esamplers among irqfds on the same gsi.
- *		    Accessed and modified under gzvm->irqfds.resampler_lock.
- *
- * Resampling irqfds are a special variety of irqfds used to emulate
- * level triggered interrupts.  The interrupt is asserted on eventfd
- * trigger.  On acknowledgment through the irq ack notifier, the
- * interrupt is de-asserted and userspace is notified through the
- * resamplefd.  All resamplers on the same gsi are de-asserted
- * together, so we don't need to track the state of each individual
- * user.  We can also therefore share the same irq source ID.
- */
-struct gzvm_kernel_irqfd_resampler {
-	struct gzvm *gzvm;
-
-	struct list_head list;
-	struct gzvm_irq_ack_notifier notifier;
-
-	struct list_head link;
-};
-
 /**
  * struct gzvm_kernel_irqfd: gzvm kernel irqfd descriptor.
  * @gzvm: Pointer to struct gzvm.
  * @wait: Wait queue entry.
  * @gsi: Used for level IRQ fast-path.
- * @resampler: The resampler used by this irqfd (resampler-only).
- * @resamplefd: Eventfd notified on resample (resampler-only).
- * @resampler_link: Entry in list of irqfds for a resampler (resampler-only).
  * @eventfd: Used for setup/shutdown.
  * @list: struct list_head.
  * @pt: struct poll_table_struct.
@@ -60,12 +30,6 @@ struct gzvm_kernel_irqfd {
 
 	int gsi;
 
-	struct gzvm_kernel_irqfd_resampler *resampler;
-
-	struct eventfd_ctx *resamplefd;
-
-	struct list_head resampler_link;
-
 	struct eventfd_ctx *eventfd;
 	struct list_head list;
 	poll_table pt;
@@ -89,77 +53,6 @@ static void irqfd_set_spi(struct gzvm *gzvm, int irq_source_id, u32 irq,
 		gzvm_irqchip_inject_irq(gzvm, irq_source_id, 0, irq, level);
 }
 
-/**
- * irqfd_resampler_ack() - Notify all of the resampler irqfds using this GSI
- *			   when IRQ de-assert once.
- * @ian: Pointer to gzvm_irq_ack_notifier.
- *
- * Since resampler irqfds share an IRQ source ID, we de-assert once
- * then notify all of the resampler irqfds using this GSI.  We can't
- * do multiple de-asserts or we risk racing with incoming re-asserts.
- */
-static void irqfd_resampler_ack(struct gzvm_irq_ack_notifier *ian)
-{
-	struct gzvm_kernel_irqfd_resampler *resampler;
-	struct gzvm *gzvm;
-	struct gzvm_kernel_irqfd *irqfd;
-	int idx;
-
-	resampler = container_of(ian,
-				 struct gzvm_kernel_irqfd_resampler, notifier);
-	gzvm = resampler->gzvm;
-
-	irqfd_set_spi(gzvm, GZVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID,
-		      resampler->notifier.gsi, 0, false);
-
-	idx = srcu_read_lock(&gzvm->irq_srcu);
-
-	list_for_each_entry_srcu(irqfd, &resampler->list, resampler_link,
-				 srcu_read_lock_held(&gzvm->irq_srcu)) {
-		eventfd_signal(irqfd->resamplefd, 1);
-	}
-
-	srcu_read_unlock(&gzvm->irq_srcu, idx);
-}
-
-static void gzvm_register_irq_ack_notifier(struct gzvm *gzvm,
-					   struct gzvm_irq_ack_notifier *ian)
-{
-	mutex_lock(&gzvm->irq_lock);
-	hlist_add_head_rcu(&ian->link, &gzvm->irq_ack_notifier_list);
-	mutex_unlock(&gzvm->irq_lock);
-}
-
-static void gzvm_unregister_irq_ack_notifier(struct gzvm *gzvm,
-					     struct gzvm_irq_ack_notifier *ian)
-{
-	mutex_lock(&gzvm->irq_lock);
-	hlist_del_init_rcu(&ian->link);
-	mutex_unlock(&gzvm->irq_lock);
-	synchronize_srcu(&gzvm->irq_srcu);
-}
-
-static void irqfd_resampler_shutdown(struct gzvm_kernel_irqfd *irqfd)
-{
-	struct gzvm_kernel_irqfd_resampler *resampler = irqfd->resampler;
-	struct gzvm *gzvm = resampler->gzvm;
-
-	mutex_lock(&gzvm->irqfds.resampler_lock);
-
-	list_del_rcu(&irqfd->resampler_link);
-	synchronize_srcu(&gzvm->irq_srcu);
-
-	if (list_empty(&resampler->list)) {
-		list_del(&resampler->link);
-		gzvm_unregister_irq_ack_notifier(gzvm, &resampler->notifier);
-		irqfd_set_spi(gzvm, GZVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID,
-			      resampler->notifier.gsi, 0, false);
-		kfree(resampler);
-	}
-
-	mutex_unlock(&gzvm->irqfds.resampler_lock);
-}
-
 /**
  * irqfd_shutdown() - Race-free decouple logic (ordering is critical).
  * @work: Pointer to work_struct.
@@ -180,11 +73,6 @@ static void irqfd_shutdown(struct work_struct *work)
 	 */
 	eventfd_ctx_remove_wait_queue(irqfd->eventfd, &irqfd->wait, &cnt);
 
-	if (irqfd->resampler) {
-		irqfd_resampler_shutdown(irqfd);
-		eventfd_ctx_put(irqfd->resamplefd);
-	}
-
 	/*
 	 * It is now safe to release the object's resources
 	 */
@@ -278,9 +166,8 @@ static int gzvm_irqfd_assign(struct gzvm *gzvm, struct gzvm_irqfd *args)
 {
 	struct gzvm_kernel_irqfd *irqfd, *tmp;
 	struct fd f;
-	struct eventfd_ctx *eventfd = NULL, *resamplefd = NULL;
+	struct eventfd_ctx *eventfd = NULL;
 	int ret;
-	__poll_t events;
 	int idx;
 
 	irqfd = kzalloc(sizeof(*irqfd), GFP_KERNEL_ACCOUNT);
@@ -289,7 +176,6 @@ static int gzvm_irqfd_assign(struct gzvm *gzvm, struct gzvm_irqfd *args)
 
 	irqfd->gzvm = gzvm;
 	irqfd->gsi = args->gsi;
-	irqfd->resampler = NULL;
 
 	INIT_LIST_HEAD(&irqfd->list);
 	INIT_WORK(&irqfd->shutdown, irqfd_shutdown);
@@ -308,55 +194,6 @@ static int gzvm_irqfd_assign(struct gzvm *gzvm, struct gzvm_irqfd *args)
 
 	irqfd->eventfd = eventfd;
 
-	if (args->flags & GZVM_IRQFD_FLAG_RESAMPLE) {
-		struct gzvm_kernel_irqfd_resampler *resampler;
-
-		resamplefd = eventfd_ctx_fdget(args->resamplefd);
-		if (IS_ERR(resamplefd)) {
-			ret = PTR_ERR(resamplefd);
-			goto fail;
-		}
-
-		irqfd->resamplefd = resamplefd;
-		INIT_LIST_HEAD(&irqfd->resampler_link);
-
-		mutex_lock(&gzvm->irqfds.resampler_lock);
-
-		list_for_each_entry(resampler,
-				    &gzvm->irqfds.resampler_list, link) {
-			if (resampler->notifier.gsi == irqfd->gsi) {
-				irqfd->resampler = resampler;
-				break;
-			}
-		}
-
-		if (!irqfd->resampler) {
-			resampler = kzalloc(sizeof(*resampler),
-					    GFP_KERNEL_ACCOUNT);
-			if (!resampler) {
-				ret = -ENOMEM;
-				mutex_unlock(&gzvm->irqfds.resampler_lock);
-				goto fail;
-			}
-
-			resampler->gzvm = gzvm;
-			INIT_LIST_HEAD(&resampler->list);
-			resampler->notifier.gsi = irqfd->gsi;
-			resampler->notifier.irq_acked = irqfd_resampler_ack;
-			INIT_LIST_HEAD(&resampler->link);
-
-			list_add(&resampler->link, &gzvm->irqfds.resampler_list);
-			gzvm_register_irq_ack_notifier(gzvm,
-						       &resampler->notifier);
-			irqfd->resampler = resampler;
-		}
-
-		list_add_rcu(&irqfd->resampler_link, &irqfd->resampler->list);
-		synchronize_srcu(&gzvm->irq_srcu);
-
-		mutex_unlock(&gzvm->irqfds.resampler_lock);
-	}
-
 	/*
 	 * Install our own custom wake-up handling so we are notified via
 	 * a callback whenever someone signals the underlying eventfd
@@ -383,16 +220,7 @@ static int gzvm_irqfd_assign(struct gzvm *gzvm, struct gzvm_irqfd *args)
 
 	spin_unlock_irq(&gzvm->irqfds.lock);
 
-	/*
+	vfs_poll(f.file, &irqfd->pt);
-	 * Check if there was an event already pending on the eventfd
-	 * before we registered, and trigger it as if we didn't miss it.
-	 */
-	events = vfs_poll(f.file, &irqfd->pt);
-
-	/* In case there is already a pending event */
-	if (events & EPOLLIN)
-		irqfd_set_spi(gzvm, GZVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID,
-			      irqfd->gsi, 1, false);
 
 	srcu_read_unlock(&gzvm->irq_srcu, idx);
 
@@ -404,12 +232,6 @@ static int gzvm_irqfd_assign(struct gzvm *gzvm, struct gzvm_irqfd *args)
 	return 0;
 
 fail:
-	if (irqfd->resampler)
-		irqfd_resampler_shutdown(irqfd);
-
-	if (resamplefd && !IS_ERR(resamplefd))
-		eventfd_ctx_put(resamplefd);
-
 	if (eventfd && !IS_ERR(eventfd))
 		eventfd_ctx_put(eventfd);
 
@@ -509,11 +331,9 @@ int gzvm_vm_irqfd_init(struct gzvm *gzvm)
 
 	spin_lock_init(&gzvm->irqfds.lock);
 	INIT_LIST_HEAD(&gzvm->irqfds.items);
-	INIT_LIST_HEAD(&gzvm->irqfds.resampler_list);
 	if (init_srcu_struct(&gzvm->irq_srcu))
 		return -EINVAL;
 	INIT_HLIST_HEAD(&gzvm->irq_ack_notifier_list);
-	mutex_init(&gzvm->irqfds.resampler_lock);
 
 	return 0;
 }