4 files changed, 19 insertions, 0 deletions

diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index 6ad4658de705..d23aa82e7a7b 100644
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -3425,6 +3425,11 @@ int get_nr_irqs_gsi(void)
         return nr_irqs_gsi;
 }
 
+unsigned int arch_dynirq_lower_bound(unsigned int from)
+{
+        return from < nr_irqs_gsi ? nr_irqs_gsi : from;
+}
+
 int __init arch_probe_nr_irqs(void)
 {
         int nr;
diff --git a/include/linux/irq.h b/include/linux/irq.h
index 10a0b1ac4ea0..5c57efb863d0 100644
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -603,6 +603,8 @@ static inline u32 irq_get_trigger_type(unsigned int irq)
         return d ? irqd_get_trigger_type(d) : 0;
 }
 
+unsigned int arch_dynirq_lower_bound(unsigned int from);
+
 int __irq_alloc_descs(int irq, unsigned int from, unsigned int cnt, int node,
                 struct module *owner);
 
diff --git a/kernel/irq/irqdesc.c b/kernel/irq/irqdesc.c
index a7174617616b..bb07f2928f4b 100644
--- a/kernel/irq/irqdesc.c
+++ b/kernel/irq/irqdesc.c
@@ -363,6 +363,13 @@ __irq_alloc_descs(int irq, unsigned int from, unsigned int cnt, int node,
                 if (from > irq)
                         return -EINVAL;
                 from = irq;
+        } else {
+                /*
+                 * For interrupts which are freely allocated the
+                 * architecture can force a lower bound to the @from
+                 * argument. x86 uses this to exclude the GSI space.
+                 */
+                from = arch_dynirq_lower_bound(from);
         }
 
         mutex_lock(&sparse_irq_lock);
diff --git a/kernel/softirq.c b/kernel/softirq.c
index b50990a5bea0..33e4648ae0e7 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -779,3 +779,8 @@ int __init __weak arch_early_irq_init(void)
 {
         return 0;
 }
+
+unsigned int __weak arch_dynirq_lower_bound(unsigned int from)
+{
+        return from;
+}