1 files changed, 460 insertions, 46 deletions

diff --git a/drivers/xen/events/events_base.c b/drivers/xen/events/events_base.c
index 140c7bf33a98..6038c4c35db5 100644
--- a/drivers/xen/events/events_base.c
+++ b/drivers/xen/events/events_base.c
@@ -33,6 +33,10 @@
 #include <linux/slab.h>
 #include <linux/irqnr.h>
 #include <linux/pci.h>
+#include <linux/spinlock.h>
+#include <linux/cpuhotplug.h>
+#include <linux/atomic.h>
+#include <linux/ktime.h>
 
 #ifdef CONFIG_X86
 #include <asm/desc.h>
@@ -63,6 +67,66 @@
 
 #include "events_internal.h"
 
+#undef MODULE_PARAM_PREFIX
+#define MODULE_PARAM_PREFIX "xen."
+
+/* Interrupt types. */
+enum xen_irq_type {
+	IRQT_UNBOUND = 0,
+	IRQT_PIRQ,
+	IRQT_VIRQ,
+	IRQT_IPI,
+	IRQT_EVTCHN
+};
+
+/*
+ * Packed IRQ information:
+ * type - enum xen_irq_type
+ * event channel - irq->event channel mapping
+ * cpu - cpu this event channel is bound to
+ * index - type-specific information:
+ *    PIRQ - vector, with MSB being "needs EIO", or physical IRQ of the HVM
+ *           guest, or GSI (real passthrough IRQ) of the device.
+ *    VIRQ - virq number
+ *    IPI - IPI vector
+ *    EVTCHN -
+ */
+struct irq_info {
+	struct list_head list;
+	struct list_head eoi_list;
+	short refcnt;
+	short spurious_cnt;
+	enum xen_irq_type type; /* type */
+	unsigned irq;
+	evtchn_port_t evtchn;   /* event channel */
+	unsigned short cpu;     /* cpu bound */
+	unsigned short eoi_cpu; /* EOI must happen on this cpu-1 */
+	unsigned int irq_epoch; /* If eoi_cpu valid: irq_epoch of event */
+	u64 eoi_time;           /* Time in jiffies when to EOI. */
+
+	union {
+		unsigned short virq;
+		enum ipi_vector ipi;
+		struct {
+			unsigned short pirq;
+			unsigned short gsi;
+			unsigned char vector;
+			unsigned char flags;
+			uint16_t domid;
+		} pirq;
+	} u;
+};
+
+#define PIRQ_NEEDS_EOI	(1 << 0)
+#define PIRQ_SHAREABLE	(1 << 1)
+#define PIRQ_MSI_GROUP	(1 << 2)
+
+static uint __read_mostly event_loop_timeout = 2;
+module_param(event_loop_timeout, uint, 0644);
+
+static uint __read_mostly event_eoi_delay = 10;
+module_param(event_eoi_delay, uint, 0644);
+
 const struct evtchn_ops *evtchn_ops;
 
 /*
@@ -71,6 +135,24 @@ const struct evtchn_ops *evtchn_ops;
  */
 static DEFINE_MUTEX(irq_mapping_update_lock);
 
+/*
+ * Lock protecting event handling loop against removing event channels.
+ * Adding of event channels is no issue as the associated IRQ becomes active
+ * only after everything is setup (before request_[threaded_]irq() the handler
+ * can't be entered for an event, as the event channel will be unmasked only
+ * then).
+ */
+static DEFINE_RWLOCK(evtchn_rwlock);
+
+/*
+ * Lock hierarchy:
+ *
+ * irq_mapping_update_lock
+ *   evtchn_rwlock
+ *     IRQ-desc lock
+ *       percpu eoi_list_lock
+ */
+
 static LIST_HEAD(xen_irq_list_head);
 
 /* IRQ <-> VIRQ mapping. */
@@ -79,7 +161,7 @@ static DEFINE_PER_CPU(int [NR_VIRQS], virq_to_irq) = {[0 ... NR_VIRQS-1] = -1};
 /* IRQ <-> IPI mapping */
 static DEFINE_PER_CPU(int [XEN_NR_IPIS], ipi_to_irq) = {[0 ... XEN_NR_IPIS-1] = -1};
 
-int **evtchn_to_irq;
+static int **evtchn_to_irq;
 #ifdef CONFIG_X86
 static unsigned long *pirq_eoi_map;
 #endif
@@ -92,18 +174,23 @@ static bool (*pirq_needs_eoi)(unsigned irq);
 /* Xen will never allocate port zero for any purpose. */
 #define VALID_EVTCHN(chn)	((chn) != 0)
 
+static struct irq_info *legacy_info_ptrs[NR_IRQS_LEGACY];
+
 static struct irq_chip xen_dynamic_chip;
+static struct irq_chip xen_lateeoi_chip;
 static struct irq_chip xen_percpu_chip;
 static struct irq_chip xen_pirq_chip;
 static void enable_dynirq(struct irq_data *data);
 static void disable_dynirq(struct irq_data *data);
 
+static DEFINE_PER_CPU(unsigned int, irq_epoch);
+
 static void clear_evtchn_to_irq_row(unsigned row)
 {
 	unsigned col;
 
 	for (col = 0; col < EVTCHN_PER_ROW; col++)
-		evtchn_to_irq[row][col] = -1;
+		WRITE_ONCE(evtchn_to_irq[row][col], -1);
 }
 
 static void clear_evtchn_to_irq_all(void)
@@ -140,7 +227,7 @@ static int set_evtchn_to_irq(evtchn_port_t evtchn, unsigned int irq)
 		clear_evtchn_to_irq_row(row);
 	}
 
-	evtchn_to_irq[row][col] = irq;
+	WRITE_ONCE(evtchn_to_irq[row][col], irq);
 	return 0;
 }
 
@@ -150,13 +237,24 @@ int get_evtchn_to_irq(evtchn_port_t evtchn)
 		return -1;
 	if (evtchn_to_irq[EVTCHN_ROW(evtchn)] == NULL)
 		return -1;
-	return evtchn_to_irq[EVTCHN_ROW(evtchn)][EVTCHN_COL(evtchn)];
+	return READ_ONCE(evtchn_to_irq[EVTCHN_ROW(evtchn)][EVTCHN_COL(evtchn)]);
 }
 
 /* Get info for IRQ */
-struct irq_info *info_for_irq(unsigned irq)
+static struct irq_info *info_for_irq(unsigned irq)
 {
-	return irq_get_handler_data(irq);
+	if (irq < nr_legacy_irqs())
+		return legacy_info_ptrs[irq];
+	else
+		return irq_get_chip_data(irq);
+}
+
+static void set_info_for_irq(unsigned int irq, struct irq_info *info)
+{
+	if (irq < nr_legacy_irqs())
+		legacy_info_ptrs[irq] = info;
+	else
+		irq_set_chip_data(irq, info);
 }
 
 /* Constructors for packed IRQ information. */
@@ -181,7 +279,7 @@ static int xen_irq_info_common_setup(struct irq_info *info,
 
 	irq_clear_status_flags(irq, IRQ_NOREQUEST|IRQ_NOAUTOEN);
 
-	return xen_evtchn_port_setup(info);
+	return xen_evtchn_port_setup(evtchn);
 }
 
 static int xen_irq_info_evtchn_setup(unsigned irq,
@@ -248,10 +346,14 @@ static void xen_irq_info_cleanup(struct irq_info *info)
  */
 evtchn_port_t evtchn_from_irq(unsigned irq)
 {
-	if (WARN(irq >= nr_irqs, "Invalid irq %d!\n", irq))
+	const struct irq_info *info = NULL;
+
+	if (likely(irq < nr_irqs))
+		info = info_for_irq(irq);
+	if (!info)
 		return 0;
 
-	return info_for_irq(irq)->evtchn;
+	return info->evtchn;
 }
 
 unsigned int irq_from_evtchn(evtchn_port_t evtchn)
@@ -300,7 +402,7 @@ static enum xen_irq_type type_from_irq(unsigned irq)
 	return info_for_irq(irq)->type;
 }
 
-unsigned cpu_from_irq(unsigned irq)
+static unsigned cpu_from_irq(unsigned irq)
 {
 	return info_for_irq(irq)->cpu;
 }
@@ -340,7 +442,7 @@ static void bind_evtchn_to_cpu(evtchn_port_t evtchn, unsigned int cpu)
 #ifdef CONFIG_SMP
 	cpumask_copy(irq_get_affinity_mask(irq), cpumask_of(cpu));
 #endif
-	xen_evtchn_port_bind_to_cpu(info, cpu);
+	xen_evtchn_port_bind_to_cpu(evtchn, cpu, info->cpu);
 
 	info->cpu = cpu;
 }
@@ -362,9 +464,157 @@ void notify_remote_via_irq(int irq)
 }
 EXPORT_SYMBOL_GPL(notify_remote_via_irq);
 
+struct lateeoi_work {
+	struct delayed_work delayed;
+	spinlock_t eoi_list_lock;
+	struct list_head eoi_list;
+};
+
+static DEFINE_PER_CPU(struct lateeoi_work, lateeoi);
+
+static void lateeoi_list_del(struct irq_info *info)
+{
+	struct lateeoi_work *eoi = &per_cpu(lateeoi, info->eoi_cpu);
+	unsigned long flags;
+
+	spin_lock_irqsave(&eoi->eoi_list_lock, flags);
+	list_del_init(&info->eoi_list);
+	spin_unlock_irqrestore(&eoi->eoi_list_lock, flags);
+}
+
+static void lateeoi_list_add(struct irq_info *info)
+{
+	struct lateeoi_work *eoi = &per_cpu(lateeoi, info->eoi_cpu);
+	struct irq_info *elem;
+	u64 now = get_jiffies_64();
+	unsigned long delay;
+	unsigned long flags;
+
+	if (now < info->eoi_time)
+		delay = info->eoi_time - now;
+	else
+		delay = 1;
+
+	spin_lock_irqsave(&eoi->eoi_list_lock, flags);
+
+	if (list_empty(&eoi->eoi_list)) {
+		list_add(&info->eoi_list, &eoi->eoi_list);
+		mod_delayed_work_on(info->eoi_cpu, system_wq,
+				    &eoi->delayed, delay);
+	} else {
+		list_for_each_entry_reverse(elem, &eoi->eoi_list, eoi_list) {
+			if (elem->eoi_time <= info->eoi_time)
+				break;
+		}
+		list_add(&info->eoi_list, &elem->eoi_list);
+	}
+
+	spin_unlock_irqrestore(&eoi->eoi_list_lock, flags);
+}
+
+static void xen_irq_lateeoi_locked(struct irq_info *info, bool spurious)
+{
+	evtchn_port_t evtchn;
+	unsigned int cpu;
+	unsigned int delay = 0;
+
+	evtchn = info->evtchn;
+	if (!VALID_EVTCHN(evtchn) || !list_empty(&info->eoi_list))
+		return;
+
+	if (spurious) {
+		if ((1 << info->spurious_cnt) < (HZ << 2))
+			info->spurious_cnt++;
+		if (info->spurious_cnt > 1) {
+			delay = 1 << (info->spurious_cnt - 2);
+			if (delay > HZ)
+				delay = HZ;
+			if (!info->eoi_time)
+				info->eoi_cpu = smp_processor_id();
+			info->eoi_time = get_jiffies_64() + delay;
+		}
+	} else {
+		info->spurious_cnt = 0;
+	}
+
+	cpu = info->eoi_cpu;
+	if (info->eoi_time &&
+	    (info->irq_epoch == per_cpu(irq_epoch, cpu) || delay)) {
+		lateeoi_list_add(info);
+		return;
+	}
+
+	info->eoi_time = 0;
+	unmask_evtchn(evtchn);
+}
+
+static void xen_irq_lateeoi_worker(struct work_struct *work)
+{
+	struct lateeoi_work *eoi;
+	struct irq_info *info;
+	u64 now = get_jiffies_64();
+	unsigned long flags;
+
+	eoi = container_of(to_delayed_work(work), struct lateeoi_work, delayed);
+
+	read_lock_irqsave(&evtchn_rwlock, flags);
+
+	while (true) {
+		spin_lock(&eoi->eoi_list_lock);
+
+		info = list_first_entry_or_null(&eoi->eoi_list, struct irq_info,
+						eoi_list);
+
+		if (info == NULL || now < info->eoi_time) {
+			spin_unlock(&eoi->eoi_list_lock);
+			break;
+		}
+
+		list_del_init(&info->eoi_list);
+
+		spin_unlock(&eoi->eoi_list_lock);
+
+		info->eoi_time = 0;
+
+		xen_irq_lateeoi_locked(info, false);
+	}
+
+	if (info)
+		mod_delayed_work_on(info->eoi_cpu, system_wq,
+				    &eoi->delayed, info->eoi_time - now);
+
+	read_unlock_irqrestore(&evtchn_rwlock, flags);
+}
+
+static void xen_cpu_init_eoi(unsigned int cpu)
+{
+	struct lateeoi_work *eoi = &per_cpu(lateeoi, cpu);
+
+	INIT_DELAYED_WORK(&eoi->delayed, xen_irq_lateeoi_worker);
+	spin_lock_init(&eoi->eoi_list_lock);
+	INIT_LIST_HEAD(&eoi->eoi_list);
+}
+
+void xen_irq_lateeoi(unsigned int irq, unsigned int eoi_flags)
+{
+	struct irq_info *info;
+	unsigned long flags;
+
+	read_lock_irqsave(&evtchn_rwlock, flags);
+
+	info = info_for_irq(irq);
+
+	if (info)
+		xen_irq_lateeoi_locked(info, eoi_flags & XEN_EOI_FLAG_SPURIOUS);
+
+	read_unlock_irqrestore(&evtchn_rwlock, flags);
+}
+EXPORT_SYMBOL_GPL(xen_irq_lateeoi);
+
 static void xen_irq_init(unsigned irq)
 {
 	struct irq_info *info;
+
 #ifdef CONFIG_SMP
 	/* By default all event channels notify CPU#0. */
 	cpumask_copy(irq_get_affinity_mask(irq), cpumask_of(0));
@@ -377,8 +627,9 @@ static void xen_irq_init(unsigned irq)
 	info->type = IRQT_UNBOUND;
 	info->refcnt = -1;
 
-	irq_set_handler_data(irq, info);
+	set_info_for_irq(irq, info);
 
+	INIT_LIST_HEAD(&info->eoi_list);
 	list_add_tail(&info->list, &xen_irq_list_head);
 }
 
@@ -426,17 +677,25 @@ static int __must_check xen_allocate_irq_gsi(unsigned gsi)
 
 static void xen_free_irq(unsigned irq)
 {
-	struct irq_info *info = irq_get_handler_data(irq);
+	struct irq_info *info = info_for_irq(irq);
+	unsigned long flags;
 
 	if (WARN_ON(!info))
 		return;
 
+	write_lock_irqsave(&evtchn_rwlock, flags);
+
+	if (!list_empty(&info->eoi_list))
+		lateeoi_list_del(info);
+
 	list_del(&info->list);
 
-	irq_set_handler_data(irq, NULL);
+	set_info_for_irq(irq, NULL);
 
 	WARN_ON(info->refcnt > 0);
 
+	write_unlock_irqrestore(&evtchn_rwlock, flags);
+
 	kfree(info);
 
 	/* Legacy IRQ descriptors are managed by the arch. */
@@ -537,7 +796,7 @@ static unsigned int __startup_pirq(unsigned int irq)
 	info->evtchn = evtchn;
 	bind_evtchn_to_cpu(evtchn, 0);
 
-	rc = xen_evtchn_port_setup(info);
+	rc = xen_evtchn_port_setup(evtchn);
 	if (rc)
 		goto err;
 
@@ -603,7 +862,7 @@ EXPORT_SYMBOL_GPL(xen_irq_from_gsi);
 static void __unbind_from_irq(unsigned int irq)
 {
 	evtchn_port_t evtchn = evtchn_from_irq(irq);
-	struct irq_info *info = irq_get_handler_data(irq);
+	struct irq_info *info = info_for_irq(irq);
 
 	if (info->refcnt > 0) {
 		info->refcnt--;
@@ -828,7 +1087,7 @@ int xen_pirq_from_irq(unsigned irq)
 }
 EXPORT_SYMBOL_GPL(xen_pirq_from_irq);
 
-int bind_evtchn_to_irq(evtchn_port_t evtchn)
+static int bind_evtchn_to_irq_chip(evtchn_port_t evtchn, struct irq_chip *chip)
 {
 	int irq;
 	int ret;
@@ -845,7 +1104,7 @@ int bind_evtchn_to_irq(evtchn_port_t evtchn)
 		if (irq < 0)
 			goto out;
 
-		irq_set_chip_and_handler_name(irq, &xen_dynamic_chip,
+		irq_set_chip_and_handler_name(irq, chip,
 					      handle_edge_irq, "event");
 
 		ret = xen_irq_info_evtchn_setup(irq, evtchn);
@@ -866,8 +1125,19 @@ out:
 
 	return irq;
 }
+
+int bind_evtchn_to_irq(evtchn_port_t evtchn)
+{
+	return bind_evtchn_to_irq_chip(evtchn, &xen_dynamic_chip);
+}
 EXPORT_SYMBOL_GPL(bind_evtchn_to_irq);
 
+int bind_evtchn_to_irq_lateeoi(evtchn_port_t evtchn)
+{
+	return bind_evtchn_to_irq_chip(evtchn, &xen_lateeoi_chip);
+}
+EXPORT_SYMBOL_GPL(bind_evtchn_to_irq_lateeoi);
+
 static int bind_ipi_to_irq(unsigned int ipi, unsigned int cpu)
 {
 	struct evtchn_bind_ipi bind_ipi;
@@ -909,8 +1179,9 @@ static int bind_ipi_to_irq(unsigned int ipi, unsigned int cpu)
 	return irq;
 }
 
-int bind_interdomain_evtchn_to_irq(unsigned int remote_domain,
-				   evtchn_port_t remote_port)
+static int bind_interdomain_evtchn_to_irq_chip(unsigned int remote_domain,
+					       evtchn_port_t remote_port,
+					       struct irq_chip *chip)
 {
 	struct evtchn_bind_interdomain bind_interdomain;
 	int err;
@@ -921,9 +1192,17 @@ int bind_interdomain_evtchn_to_irq(unsigned int remote_domain,
 	err = HYPERVISOR_event_channel_op(EVTCHNOP_bind_interdomain,
 					  &bind_interdomain);
 
-	return err ? : bind_evtchn_to_irq(bind_interdomain.local_port);
+	return err ? : bind_evtchn_to_irq_chip(bind_interdomain.local_port,
+					       chip);
+}
+
+int bind_interdomain_evtchn_to_irq_lateeoi(unsigned int remote_domain,
+					   evtchn_port_t remote_port)
+{
+	return bind_interdomain_evtchn_to_irq_chip(remote_domain, remote_port,
+						   &xen_lateeoi_chip);
 }
-EXPORT_SYMBOL_GPL(bind_interdomain_evtchn_to_irq);
+EXPORT_SYMBOL_GPL(bind_interdomain_evtchn_to_irq_lateeoi);
 
 static int find_virq(unsigned int virq, unsigned int cpu, evtchn_port_t *evtchn)
 {
@@ -1021,14 +1300,15 @@ static void unbind_from_irq(unsigned int irq)
 	mutex_unlock(&irq_mapping_update_lock);
 }
 
-int bind_evtchn_to_irqhandler(evtchn_port_t evtchn,
-			      irq_handler_t handler,
-			      unsigned long irqflags,
-			      const char *devname, void *dev_id)
+static int bind_evtchn_to_irqhandler_chip(evtchn_port_t evtchn,
+					  irq_handler_t handler,
+					  unsigned long irqflags,
+					  const char *devname, void *dev_id,
+					  struct irq_chip *chip)
 {
 	int irq, retval;
 
-	irq = bind_evtchn_to_irq(evtchn);
+	irq = bind_evtchn_to_irq_chip(evtchn, chip);
 	if (irq < 0)
 		return irq;
 	retval = request_irq(irq, handler, irqflags, devname, dev_id);
@@ -1039,18 +1319,38 @@ int bind_evtchn_to_irqhandler(evtchn_port_t evtchn,
 
 	return irq;
 }
+
+int bind_evtchn_to_irqhandler(evtchn_port_t evtchn,
+			      irq_handler_t handler,
+			      unsigned long irqflags,
+			      const char *devname, void *dev_id)
+{
+	return bind_evtchn_to_irqhandler_chip(evtchn, handler, irqflags,
+					      devname, dev_id,
+					      &xen_dynamic_chip);
+}
 EXPORT_SYMBOL_GPL(bind_evtchn_to_irqhandler);
 
-int bind_interdomain_evtchn_to_irqhandler(unsigned int remote_domain,
-					  evtchn_port_t remote_port,
-					  irq_handler_t handler,
-					  unsigned long irqflags,
-					  const char *devname,
-					  void *dev_id)
+int bind_evtchn_to_irqhandler_lateeoi(evtchn_port_t evtchn,
+				      irq_handler_t handler,
+				      unsigned long irqflags,
+				      const char *devname, void *dev_id)
+{
+	return bind_evtchn_to_irqhandler_chip(evtchn, handler, irqflags,
+					      devname, dev_id,
+					      &xen_lateeoi_chip);
+}
+EXPORT_SYMBOL_GPL(bind_evtchn_to_irqhandler_lateeoi);
+
+static int bind_interdomain_evtchn_to_irqhandler_chip(
+		unsigned int remote_domain, evtchn_port_t remote_port,
+		irq_handler_t handler, unsigned long irqflags,
+		const char *devname, void *dev_id, struct irq_chip *chip)
 {
 	int irq, retval;
 
-	irq = bind_interdomain_evtchn_to_irq(remote_domain, remote_port);
+	irq = bind_interdomain_evtchn_to_irq_chip(remote_domain, remote_port,
+						  chip);
 	if (irq < 0)
 		return irq;
 
@@ -1062,7 +1362,19 @@ int bind_interdomain_evtchn_to_irqhandler(unsigned int remote_domain,
 
 	return irq;
 }
-EXPORT_SYMBOL_GPL(bind_interdomain_evtchn_to_irqhandler);
+
+int bind_interdomain_evtchn_to_irqhandler_lateeoi(unsigned int remote_domain,
+						  evtchn_port_t remote_port,
+						  irq_handler_t handler,
+						  unsigned long irqflags,
+						  const char *devname,
+						  void *dev_id)
+{
+	return bind_interdomain_evtchn_to_irqhandler_chip(remote_domain,
+				remote_port, handler, irqflags, devname,
+				dev_id, &xen_lateeoi_chip);
+}
+EXPORT_SYMBOL_GPL(bind_interdomain_evtchn_to_irqhandler_lateeoi);
 
 int bind_virq_to_irqhandler(unsigned int virq, unsigned int cpu,
 			    irq_handler_t handler,
@@ -1108,7 +1420,7 @@ int bind_ipi_to_irqhandler(enum ipi_vector ipi,
 
 void unbind_from_irqhandler(unsigned int irq, void *dev_id)
 {
-	struct irq_info *info = irq_get_handler_data(irq);
+	struct irq_info *info = info_for_irq(irq);
 
 	if (WARN_ON(!info))
 		return;
@@ -1142,7 +1454,7 @@ int evtchn_make_refcounted(evtchn_port_t evtchn)
 	if (irq == -1)
 		return -ENOENT;
 
-	info = irq_get_handler_data(irq);
+	info = info_for_irq(irq);
 
 	if (!info)
 		return -ENOENT;
@@ -1170,13 +1482,13 @@ int evtchn_get(evtchn_port_t evtchn)
 	if (irq == -1)
 		goto done;
 
-	info = irq_get_handler_data(irq);
+	info = info_for_irq(irq);
 
 	if (!info)
 		goto done;
 
 	err = -EINVAL;
-	if (info->refcnt <= 0)
+	if (info->refcnt <= 0 || info->refcnt == SHRT_MAX)
 		goto done;
 
 	info->refcnt++;
@@ -1215,21 +1527,81 @@ void xen_send_IPI_one(unsigned int cpu, enum ipi_vector vector)
 	notify_remote_via_irq(irq);
 }
 
+struct evtchn_loop_ctrl {
+	ktime_t timeout;
+	unsigned count;
+	bool defer_eoi;
+};
+
+void handle_irq_for_port(evtchn_port_t port, struct evtchn_loop_ctrl *ctrl)
+{
+	int irq;
+	struct irq_info *info;
+
+	irq = get_evtchn_to_irq(port);
+	if (irq == -1)
+		return;
+
+	/*
+	 * Check for timeout every 256 events.
+	 * We are setting the timeout value only after the first 256
+	 * events in order to not hurt the common case of few loop
+	 * iterations. The 256 is basically an arbitrary value.
+	 *
+	 * In case we are hitting the timeout we need to defer all further
+	 * EOIs in order to ensure to leave the event handling loop rather
+	 * sooner than later.
+	 */
+	if (!ctrl->defer_eoi && !(++ctrl->count & 0xff)) {
+		ktime_t kt = ktime_get();
+
+		if (!ctrl->timeout) {
+			kt = ktime_add_ms(kt,
+					  jiffies_to_msecs(event_loop_timeout));
+			ctrl->timeout = kt;
+		} else if (kt > ctrl->timeout) {
+			ctrl->defer_eoi = true;
+		}
+	}
+
+	info = info_for_irq(irq);
+
+	if (ctrl->defer_eoi) {
+		info->eoi_cpu = smp_processor_id();
+		info->irq_epoch = __this_cpu_read(irq_epoch);
+		info->eoi_time = get_jiffies_64() + event_eoi_delay;
+	}
+
+	generic_handle_irq(irq);
+}
+
 static void __xen_evtchn_do_upcall(void)
 {
 	struct vcpu_info *vcpu_info = __this_cpu_read(xen_vcpu);
 	int cpu = smp_processor_id();
+	struct evtchn_loop_ctrl ctrl = { 0 };
+
+	read_lock(&evtchn_rwlock);
 
 	do {
 		vcpu_info->evtchn_upcall_pending = 0;
 
-		xen_evtchn_handle_events(cpu);
+		xen_evtchn_handle_events(cpu, &ctrl);
 
 		BUG_ON(!irqs_disabled());
 
 		virt_rmb(); /* Hypervisor can set upcall pending. */
 
 	} while (vcpu_info->evtchn_upcall_pending);
+
+	read_unlock(&evtchn_rwlock);
+
+	/*
+	 * Increment irq_epoch only now to defer EOIs only for
+	 * xen_irq_lateeoi() invocations occurring from inside the loop
+	 * above.
+	 */
+	__this_cpu_inc(irq_epoch);
 }
 
 void xen_evtchn_do_upcall(struct pt_regs *regs)
@@ -1593,6 +1965,21 @@ static struct irq_chip xen_dynamic_chip __read_mostly = {
 	.irq_retrigger		= retrigger_dynirq,
 };
 
+static struct irq_chip xen_lateeoi_chip __read_mostly = {
+	/* The chip name needs to contain "xen-dyn" for irqbalance to work. */
+	.name			= "xen-dyn-lateeoi",
+
+	.irq_disable		= disable_dynirq,
+	.irq_mask		= disable_dynirq,
+	.irq_unmask		= enable_dynirq,
+
+	.irq_ack		= mask_ack_dynirq,
+	.irq_mask_ack		= mask_ack_dynirq,
+
+	.irq_set_affinity	= set_affinity_irq,
+	.irq_retrigger		= retrigger_dynirq,
+};
+
 static struct irq_chip xen_pirq_chip __read_mostly = {
 	.name			= "xen-pirq",
 
@@ -1663,21 +2050,48 @@ void xen_setup_callback_vector(void) {}
 static inline void xen_alloc_callback_vector(void) {}
 #endif
 
-#undef MODULE_PARAM_PREFIX
-#define MODULE_PARAM_PREFIX "xen."
+bool xen_fifo_events = true;
+module_param_named(fifo_events, xen_fifo_events, bool, 0);
 
-static bool fifo_events = true;
-module_param(fifo_events, bool, 0);
+static int xen_evtchn_cpu_prepare(unsigned int cpu)
+{
+	int ret = 0;
+
+	xen_cpu_init_eoi(cpu);
+
+	if (evtchn_ops->percpu_init)
+		ret = evtchn_ops->percpu_init(cpu);
+
+	return ret;
+}
+
+static int xen_evtchn_cpu_dead(unsigned int cpu)
+{
+	int ret = 0;
+
+	if (evtchn_ops->percpu_deinit)
+		ret = evtchn_ops->percpu_deinit(cpu);
+
+	return ret;
+}
 
 void __init xen_init_IRQ(void)
 {
 	int ret = -EINVAL;
 	evtchn_port_t evtchn;
 
-	if (fifo_events)
+	if (xen_fifo_events)
 		ret = xen_evtchn_fifo_init();
-	if (ret < 0)
+	if (ret < 0) {
 		xen_evtchn_2l_init();
+		xen_fifo_events = false;
+	}
+
+	xen_cpu_init_eoi(smp_processor_id());
+
+	cpuhp_setup_state_nocalls(CPUHP_XEN_EVTCHN_PREPARE,
+				  "xen/evtchn:prepare",
+				  xen_evtchn_cpu_prepare, xen_evtchn_cpu_dead);
 
 	evtchn_to_irq = kcalloc(EVTCHN_ROW(xen_evtchn_max_channels()),
 				sizeof(*evtchn_to_irq), GFP_KERNEL);