1 files changed, 96 insertions, 6 deletions

diff --git a/arch/x86/kernel/irq.c b/arch/x86/kernel/irq.c
index 22d0687..283a76a 100644
--- a/arch/x86/kernel/irq.c
+++ b/arch/x86/kernel/irq.c
@@ -125,6 +125,12 @@ int arch_show_interrupts(struct seq_file *p, int prec)
 		seq_printf(p, "%10u ", per_cpu(mce_poll_count, j));
 	seq_printf(p, "  Machine check polls\n");
 #endif
+#if IS_ENABLED(CONFIG_HYPERV) || defined(CONFIG_XEN)
+	seq_printf(p, "%*s: ", prec, "THR");
+	for_each_online_cpu(j)
+		seq_printf(p, "%10u ", irq_stats(j)->irq_hv_callback_count);
+	seq_printf(p, "  Hypervisor callback interrupts\n");
+#endif
 	seq_printf(p, "%*s: %10u\n", prec, "ERR", atomic_read(&irq_err_count));
 #if defined(CONFIG_X86_IO_APIC)
 	seq_printf(p, "%*s: %10u\n", prec, "MIS", atomic_read(&irq_mis_count));
@@ -193,9 +199,13 @@ __visible unsigned int __irq_entry do_IRQ(struct pt_regs *regs)
 	if (!handle_irq(irq, regs)) {
 		ack_APIC_irq();
 
-		if (printk_ratelimit())
-			pr_emerg("%s: %d.%d No irq handler for vector (irq %d)\n",
-				__func__, smp_processor_id(), vector, irq);
+		if (irq != VECTOR_RETRIGGERED) {
+			pr_emerg_ratelimited("%s: %d.%d No irq handler for vector (irq %d)\n",
+					     __func__, smp_processor_id(),
+					     vector, irq);
+		} else {
+			__this_cpu_write(vector_irq[vector], VECTOR_UNDEFINED);
+		}
 	}
 
 	irq_exit();
@@ -262,6 +272,83 @@ __visible void smp_trace_x86_platform_ipi(struct pt_regs *regs)
 EXPORT_SYMBOL_GPL(vector_used_by_percpu_irq);
 
 #ifdef CONFIG_HOTPLUG_CPU
+
+/* These two declarations are only used in check_irq_vectors_for_cpu_disable()
+ * below, which is protected by stop_machine().  Putting them on the stack
+ * results in a stack frame overflow.  Dynamically allocating could result in a
+ * failure so declare these two cpumasks as global.
+ */
+static struct cpumask affinity_new, online_new;
+
+/*
+ * This cpu is going to be removed and its vectors migrated to the remaining
+ * online cpus.  Check to see if there are enough vectors in the remaining cpus.
+ * This function is protected by stop_machine().
+ */
+int check_irq_vectors_for_cpu_disable(void)
+{
+	int irq, cpu;
+	unsigned int this_cpu, vector, this_count, count;
+	struct irq_desc *desc;
+	struct irq_data *data;
+
+	this_cpu = smp_processor_id();
+	cpumask_copy(&online_new, cpu_online_mask);
+	cpu_clear(this_cpu, online_new);
+
+	this_count = 0;
+	for (vector = FIRST_EXTERNAL_VECTOR; vector < NR_VECTORS; vector++) {
+		irq = __this_cpu_read(vector_irq[vector]);
+		if (irq >= 0) {
+			desc = irq_to_desc(irq);
+			data = irq_desc_get_irq_data(desc);
+			cpumask_copy(&affinity_new, data->affinity);
+			cpu_clear(this_cpu, affinity_new);
+
+			/* Do not count inactive or per-cpu irqs. */
+			if (!irq_has_action(irq) || irqd_is_per_cpu(data))
+				continue;
+
+			/*
+			 * A single irq may be mapped to multiple
+			 * cpu's vector_irq[] (for example IOAPIC cluster
+			 * mode).  In this case we have two
+			 * possibilities:
+			 *
+			 * 1) the resulting affinity mask is empty; that is
+			 * this the down'd cpu is the last cpu in the irq's
+			 * affinity mask, or
+			 *
+			 * 2) the resulting affinity mask is no longer
+			 * a subset of the online cpus but the affinity
+			 * mask is not zero; that is the down'd cpu is the
+			 * last online cpu in a user set affinity mask.
+			 */
+			if (cpumask_empty(&affinity_new) ||
+			    !cpumask_subset(&affinity_new, &online_new))
+				this_count++;
+		}
+	}
+
+	count = 0;
+	for_each_online_cpu(cpu) {
+		if (cpu == this_cpu)
+			continue;
+		for (vector = FIRST_EXTERNAL_VECTOR; vector < NR_VECTORS;
+		     vector++) {
+			if (per_cpu(vector_irq, cpu)[vector] < 0)
+				count++;
+		}
+	}
+
+	if (count < this_count) {
+		pr_warn("CPU %d disable failed: CPU has %u vectors assigned and there are only %u available.\n",
+			this_cpu, this_count, count);
+		return -ERANGE;
+	}
+	return 0;
+}
+
 /* A cpu has been removed from cpu_online_mask.  Reset irq affinities. */
 void fixup_irqs(void)
 {
@@ -344,7 +431,7 @@ void fixup_irqs(void)
 	for (vector = FIRST_EXTERNAL_VECTOR; vector < NR_VECTORS; vector++) {
 		unsigned int irr;
 
-		if (__this_cpu_read(vector_irq[vector]) < 0)
+		if (__this_cpu_read(vector_irq[vector]) <= VECTOR_UNDEFINED)
 			continue;
 
 		irr = apic_read(APIC_IRR + (vector / 32 * 0x10));
@@ -355,11 +442,14 @@ void fixup_irqs(void)
 			data = irq_desc_get_irq_data(desc);
 			chip = irq_data_get_irq_chip(data);
 			raw_spin_lock(&desc->lock);
-			if (chip->irq_retrigger)
+			if (chip->irq_retrigger) {
 				chip->irq_retrigger(data);
+				__this_cpu_write(vector_irq[vector], VECTOR_RETRIGGERED);
+			}
 			raw_spin_unlock(&desc->lock);
 		}
-		__this_cpu_write(vector_irq[vector], -1);
+		if (__this_cpu_read(vector_irq[vector]) != VECTOR_RETRIGGERED)
+			__this_cpu_write(vector_irq[vector], VECTOR_UNDEFINED);
 	}
 }
 #endif