Merge tag 'irq-core-2020-12-23' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull irq updates from Thomas Gleixner:
 "This is the second attempt after the first one failed miserably and
  got zapped to unblock the rest of the interrupt related patches.

  A treewide cleanup of interrupt descriptor (ab)use with all sorts of
  racy accesses, inefficient and disfunctional code. The goal is to
  remove the export of irq_to_desc() to prevent these things from
  creeping up again"

* tag 'irq-core-2020-12-23' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (30 commits)
  genirq: Restrict export of irq_to_desc()
  xen/events: Implement irq distribution
  xen/events: Reduce irq_info:: Spurious_cnt storage size
  xen/events: Only force affinity mask for percpu interrupts
  xen/events: Use immediate affinity setting
  xen/events: Remove disfunct affinity spreading
  xen/events: Remove unused bind_evtchn_to_irq_lateeoi()
  net/mlx5: Use effective interrupt affinity
  net/mlx5: Replace irq_to_desc() abuse
  net/mlx4: Use effective interrupt affinity
  net/mlx4: Replace irq_to_desc() abuse
  PCI: mobiveil: Use irq_data_get_irq_chip_data()
  PCI: xilinx-nwl: Use irq_data_get_irq_chip_data()
  NTB/msi: Use irq_has_action()
  mfd: ab8500-debugfs: Remove the racy fiddling with irq_desc
  pinctrl: nomadik: Use irq_has_action()
  drm/i915/pmu: Replace open coded kstat_irqs() copy
  drm/i915/lpe_audio: Remove pointless irq_to_desc() usage
  s390/irq: Use irq_desc_kstat_cpu() in show_msi_interrupt()
  parisc/irq: Use irq_desc_kstat_cpu() in show_interrupts()
  ...

2 files changed, 117 insertions, 99 deletions

diff --git a/drivers/xen/events/events_base.c b/drivers/xen/events/events_base.c
index 6038c4c35db5..a8030332a191 100644
--- a/drivers/xen/events/events_base.c
+++ b/drivers/xen/events/events_base.c
@@ -95,7 +95,8 @@ struct irq_info {
 	struct list_head list;
 	struct list_head eoi_list;
 	short refcnt;
-	short spurious_cnt;
+	u8 spurious_cnt;
+	u8 is_accounted;
 	enum xen_irq_type type; /* type */
 	unsigned irq;
 	evtchn_port_t evtchn;   /* event channel */
@@ -161,6 +162,9 @@ 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};
 
+/* Event channel distribution data */
+static atomic_t channels_on_cpu[NR_CPUS];
+
 static int **evtchn_to_irq;
 #ifdef CONFIG_X86
 static unsigned long *pirq_eoi_map;
@@ -257,6 +261,32 @@ static void set_info_for_irq(unsigned int irq, struct irq_info *info)
 		irq_set_chip_data(irq, info);
 }
 
+/* Per CPU channel accounting */
+static void channels_on_cpu_dec(struct irq_info *info)
+{
+	if (!info->is_accounted)
+		return;
+
+	info->is_accounted = 0;
+
+	if (WARN_ON_ONCE(info->cpu >= nr_cpu_ids))
+		return;
+
+	WARN_ON_ONCE(!atomic_add_unless(&channels_on_cpu[info->cpu], -1 , 0));
+}
+
+static void channels_on_cpu_inc(struct irq_info *info)
+{
+	if (WARN_ON_ONCE(info->cpu >= nr_cpu_ids))
+		return;
+
+	if (WARN_ON_ONCE(!atomic_add_unless(&channels_on_cpu[info->cpu], 1,
+					    INT_MAX)))
+		return;
+
+	info->is_accounted = 1;
+}
+
 /* Constructors for packed IRQ information. */
 static int xen_irq_info_common_setup(struct irq_info *info,
 				     unsigned irq,
@@ -339,6 +369,7 @@ static void xen_irq_info_cleanup(struct irq_info *info)
 {
 	set_evtchn_to_irq(info->evtchn, -1);
 	info->evtchn = 0;
+	channels_on_cpu_dec(info);
 }
 
 /*
@@ -433,18 +464,25 @@ static bool pirq_needs_eoi_flag(unsigned irq)
 	return info->u.pirq.flags & PIRQ_NEEDS_EOI;
 }
 
-static void bind_evtchn_to_cpu(evtchn_port_t evtchn, unsigned int cpu)
+static void bind_evtchn_to_cpu(evtchn_port_t evtchn, unsigned int cpu,
+			       bool force_affinity)
 {
 	int irq = get_evtchn_to_irq(evtchn);
 	struct irq_info *info = info_for_irq(irq);
 
 	BUG_ON(irq == -1);
-#ifdef CONFIG_SMP
-	cpumask_copy(irq_get_affinity_mask(irq), cpumask_of(cpu));
-#endif
+
+	if (IS_ENABLED(CONFIG_SMP) && force_affinity) {
+		cpumask_copy(irq_get_affinity_mask(irq), cpumask_of(cpu));
+		cpumask_copy(irq_get_effective_affinity_mask(irq),
+			     cpumask_of(cpu));
+	}
+
 	xen_evtchn_port_bind_to_cpu(evtchn, cpu, info->cpu);
 
+	channels_on_cpu_dec(info);
 	info->cpu = cpu;
+	channels_on_cpu_inc(info);
 }
 
 /**
@@ -523,8 +561,10 @@ static void xen_irq_lateeoi_locked(struct irq_info *info, bool spurious)
 		return;
 
 	if (spurious) {
-		if ((1 << info->spurious_cnt) < (HZ << 2))
-			info->spurious_cnt++;
+		if ((1 << info->spurious_cnt) < (HZ << 2)) {
+			if (info->spurious_cnt != 0xFF)
+				info->spurious_cnt++;
+		}
 		if (info->spurious_cnt > 1) {
 			delay = 1 << (info->spurious_cnt - 2);
 			if (delay > HZ)
@@ -615,11 +655,6 @@ 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));
-#endif
-
 	info = kzalloc(sizeof(*info), GFP_KERNEL);
 	if (info == NULL)
 		panic("Unable to allocate metadata for IRQ%d\n", irq);
@@ -628,6 +663,11 @@ static void xen_irq_init(unsigned irq)
 	info->refcnt = -1;
 
 	set_info_for_irq(irq, info);
+	/*
+	 * Interrupt affinity setting can be immediate. No point
+	 * in delaying it until an interrupt is handled.
+	 */
+	irq_set_status_flags(irq, IRQ_MOVE_PCNTXT);
 
 	INIT_LIST_HEAD(&info->eoi_list);
 	list_add_tail(&info->list, &xen_irq_list_head);
@@ -739,18 +779,7 @@ static void eoi_pirq(struct irq_data *data)
 	if (!VALID_EVTCHN(evtchn))
 		return;
 
-	if (unlikely(irqd_is_setaffinity_pending(data)) &&
-	    likely(!irqd_irq_disabled(data))) {
-		int masked = test_and_set_mask(evtchn);
-
-		clear_evtchn(evtchn);
-
-		irq_move_masked_irq(data);
-
-		if (!masked)
-			unmask_evtchn(evtchn);
-	} else
-		clear_evtchn(evtchn);
+	clear_evtchn(evtchn);
 
 	if (pirq_needs_eoi(data->irq)) {
 		rc = HYPERVISOR_physdev_op(PHYSDEVOP_eoi, &eoi);
@@ -794,7 +823,7 @@ static unsigned int __startup_pirq(unsigned int irq)
 		goto err;
 
 	info->evtchn = evtchn;
-	bind_evtchn_to_cpu(evtchn, 0);
+	bind_evtchn_to_cpu(evtchn, 0, false);
 
 	rc = xen_evtchn_port_setup(evtchn);
 	if (rc)
@@ -1113,8 +1142,14 @@ static int bind_evtchn_to_irq_chip(evtchn_port_t evtchn, struct irq_chip *chip)
 			irq = ret;
 			goto out;
 		}
-		/* New interdomain events are bound to VCPU 0. */
-		bind_evtchn_to_cpu(evtchn, 0);
+		/*
+		 * New interdomain events are initially bound to vCPU0 This
+		 * is required to setup the event channel in the first
+		 * place and also important for UP guests because the
+		 * affinity setting is not invoked on them so nothing would
+		 * bind the channel.
+		 */
+		bind_evtchn_to_cpu(evtchn, 0, false);
 	} else {
 		struct irq_info *info = info_for_irq(irq);
 		WARN_ON(info == NULL || info->type != IRQT_EVTCHN);
@@ -1132,12 +1167,6 @@ int bind_evtchn_to_irq(evtchn_port_t evtchn)
 }
 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;
@@ -1168,7 +1197,11 @@ static int bind_ipi_to_irq(unsigned int ipi, unsigned int cpu)
 			irq = ret;
 			goto out;
 		}
-		bind_evtchn_to_cpu(evtchn, cpu);
+		/*
+		 * Force the affinity mask to the target CPU so proc shows
+		 * the correct target.
+		 */
+		bind_evtchn_to_cpu(evtchn, cpu, true);
 	} else {
 		struct irq_info *info = info_for_irq(irq);
 		WARN_ON(info == NULL || info->type != IRQT_IPI);
@@ -1281,7 +1314,11 @@ int bind_virq_to_irq(unsigned int virq, unsigned int cpu, bool percpu)
 			goto out;
 		}
 
-		bind_evtchn_to_cpu(evtchn, cpu);
+		/*
+		 * Force the affinity mask for percpu interrupts so proc
+		 * shows the correct target.
+		 */
+		bind_evtchn_to_cpu(evtchn, cpu, percpu);
 	} else {
 		struct irq_info *info = info_for_irq(irq);
 		WARN_ON(info == NULL || info->type != IRQT_VIRQ);
@@ -1646,9 +1683,7 @@ void rebind_evtchn_irq(evtchn_port_t evtchn, int irq)
 
 	mutex_unlock(&irq_mapping_update_lock);
 
-        bind_evtchn_to_cpu(evtchn, info->cpu);
-	/* This will be deferred until interrupt is processed */
-	irq_set_affinity(irq, cpumask_of(info->cpu));
+	bind_evtchn_to_cpu(evtchn, info->cpu, false);
 
 	/* Unmask the event channel. */
 	enable_irq(irq);
@@ -1682,7 +1717,7 @@ static int xen_rebind_evtchn_to_cpu(evtchn_port_t evtchn, unsigned int tcpu)
 	 * it, but don't do the xenlinux-level rebind in that case.
 	 */
 	if (HYPERVISOR_event_channel_op(EVTCHNOP_bind_vcpu, &bind_vcpu) >= 0)
-		bind_evtchn_to_cpu(evtchn, tcpu);
+		bind_evtchn_to_cpu(evtchn, tcpu, false);
 
 	if (!masked)
 		unmask_evtchn(evtchn);
@@ -1690,27 +1725,47 @@ static int xen_rebind_evtchn_to_cpu(evtchn_port_t evtchn, unsigned int tcpu)
 	return 0;
 }
 
+/*
+ * Find the CPU within @dest mask which has the least number of channels
+ * assigned. This is not precise as the per cpu counts can be modified
+ * concurrently.
+ */
+static unsigned int select_target_cpu(const struct cpumask *dest)
+{
+	unsigned int cpu, best_cpu = UINT_MAX, minch = UINT_MAX;
+
+	for_each_cpu_and(cpu, dest, cpu_online_mask) {
+		unsigned int curch = atomic_read(&channels_on_cpu[cpu]);
+
+		if (curch < minch) {
+			minch = curch;
+			best_cpu = cpu;
+		}
+	}
+
+	/*
+	 * Catch the unlikely case that dest contains no online CPUs. Can't
+	 * recurse.
+	 */
+	if (best_cpu == UINT_MAX)
+		return select_target_cpu(cpu_online_mask);
+
+	return best_cpu;
+}
+
 static int set_affinity_irq(struct irq_data *data, const struct cpumask *dest,
 			    bool force)
 {
-	unsigned tcpu = cpumask_first_and(dest, cpu_online_mask);
-	int ret = xen_rebind_evtchn_to_cpu(evtchn_from_irq(data->irq), tcpu);
+	unsigned int tcpu = select_target_cpu(dest);
+	int ret;
 
+	ret = xen_rebind_evtchn_to_cpu(evtchn_from_irq(data->irq), tcpu);
 	if (!ret)
 		irq_data_update_effective_affinity(data, cpumask_of(tcpu));
 
 	return ret;
 }
 
-/* To be called with desc->lock held. */
-int xen_set_affinity_evtchn(struct irq_desc *desc, unsigned int tcpu)
-{
-	struct irq_data *d = irq_desc_get_irq_data(desc);
-
-	return set_affinity_irq(d, cpumask_of(tcpu), false);
-}
-EXPORT_SYMBOL_GPL(xen_set_affinity_evtchn);
-
 static void enable_dynirq(struct irq_data *data)
 {
 	evtchn_port_t evtchn = evtchn_from_irq(data->irq);
@@ -1734,18 +1789,7 @@ static void ack_dynirq(struct irq_data *data)
 	if (!VALID_EVTCHN(evtchn))
 		return;
 
-	if (unlikely(irqd_is_setaffinity_pending(data)) &&
-	    likely(!irqd_irq_disabled(data))) {
-		int masked = test_and_set_mask(evtchn);
-
-		clear_evtchn(evtchn);
-
-		irq_move_masked_irq(data);
-
-		if (!masked)
-			unmask_evtchn(evtchn);
-	} else
-		clear_evtchn(evtchn);
+	clear_evtchn(evtchn);
 }
 
 static void mask_ack_dynirq(struct irq_data *data)
@@ -1830,7 +1874,8 @@ static void restore_cpu_virqs(unsigned int cpu)
 
 		/* Record the new mapping. */
 		(void)xen_irq_info_virq_setup(cpu, irq, evtchn, virq);
-		bind_evtchn_to_cpu(evtchn, cpu);
+		/* The affinity mask is still valid */
+		bind_evtchn_to_cpu(evtchn, cpu, false);
 	}
 }
 
@@ -1855,7 +1900,8 @@ static void restore_cpu_ipis(unsigned int cpu)
 
 		/* Record the new mapping. */
 		(void)xen_irq_info_ipi_setup(cpu, irq, evtchn, ipi);
-		bind_evtchn_to_cpu(evtchn, cpu);
+		/* The affinity mask is still valid */
+		bind_evtchn_to_cpu(evtchn, cpu, false);
 	}
 }
 
@@ -1938,8 +1984,12 @@ void xen_irq_resume(void)
 	xen_evtchn_resume();
 
 	/* No IRQ <-> event-channel mappings. */
-	list_for_each_entry(info, &xen_irq_list_head, list)
-		info->evtchn = 0; /* zap event-channel binding */
+	list_for_each_entry(info, &xen_irq_list_head, list) {
+		/* Zap event-channel binding */
+		info->evtchn = 0;
+		/* Adjust accounting */
+		channels_on_cpu_dec(info);
+	}
 
 	clear_evtchn_to_irq_all();
 
diff --git a/drivers/xen/evtchn.c b/drivers/xen/evtchn.c
index 5dc016d68f83..a7a85719a8c8 100644
--- a/drivers/xen/evtchn.c
+++ b/drivers/xen/evtchn.c
@@ -421,36 +421,6 @@ static void evtchn_unbind_from_user(struct per_user_data *u,
 	del_evtchn(u, evtchn);
 }
 
-static DEFINE_PER_CPU(int, bind_last_selected_cpu);
-
-static void evtchn_bind_interdom_next_vcpu(evtchn_port_t evtchn)
-{
-	unsigned int selected_cpu, irq;
-	struct irq_desc *desc;
-	unsigned long flags;
-
-	irq = irq_from_evtchn(evtchn);
-	desc = irq_to_desc(irq);
-
-	if (!desc)
-		return;
-
-	raw_spin_lock_irqsave(&desc->lock, flags);
-	selected_cpu = this_cpu_read(bind_last_selected_cpu);
-	selected_cpu = cpumask_next_and(selected_cpu,
-			desc->irq_common_data.affinity, cpu_online_mask);
-
-	if (unlikely(selected_cpu >= nr_cpu_ids))
-		selected_cpu = cpumask_first_and(desc->irq_common_data.affinity,
-				cpu_online_mask);
-
-	this_cpu_write(bind_last_selected_cpu, selected_cpu);
-
-	/* unmask expects irqs to be disabled */
-	xen_set_affinity_evtchn(desc, selected_cpu);
-	raw_spin_unlock_irqrestore(&desc->lock, flags);
-}
-
 static long evtchn_ioctl(struct file *file,
 			 unsigned int cmd, unsigned long arg)
 {
@@ -508,10 +478,8 @@ static long evtchn_ioctl(struct file *file,
 			break;
 
 		rc = evtchn_bind_to_user(u, bind_interdomain.local_port);
-		if (rc == 0) {
+		if (rc == 0)
 			rc = bind_interdomain.local_port;
-			evtchn_bind_interdom_next_vcpu(rc);
-		}
 		break;
 	}