Patch "xen/events: Always allocate legacy interrupts on PV guests" has been added to the 4.3-stable tree

This is a note to let you know that I've just added the patch titled

xen/events: Always allocate legacy interrupts on PV guests

to the 4.3-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
xen-events-always-allocate-legacy-interrupts-on-pv-guests.patch
and it can be found in the queue-4.3 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Boris Ostrovsky <[email protected]>
Date: Fri, 20 Nov 2015 11:25:04 -0500
Subject: xen/events: Always allocate legacy interrupts on PV guests

From: Boris Ostrovsky <[email protected]>

commit b4ff8389ed14b849354b59ce9b360bdefcdbf99c upstream.

After commit 8c058b0b9c34 ("x86/irq: Probe for PIC presence before allocating descs for legacy IRQs") early_irq_init() will no longer preallocate descriptors for legacy interrupts if PIC does not exist, which is the case for Xen PV guests.

Therefore we may need to allocate those descriptors ourselves.

---
 arch/arm/include/asm/irq.h       |    5 +++++
 arch/arm64/include/asm/irq.h     |    5 +++++
 drivers/xen/events/events_base.c |    5 +++--
 3 files changed, 13 insertions(+), 2 deletions(-)

@@ -40,6 +40,11 @@ extern void arch_trigger_all_cpu_backtra
 #define arch_trigger_all_cpu_backtrace(x) arch_trigger_all_cpu_backtrace(x)
 #endif
 
+static inline int nr_legacy_irqs(void)
+{
+	return NR_IRQS_LEGACY;
+}
+
 #endif
 
 #endif

@@ -21,4 +21,9 @@ static inline void acpi_irq_init(void)
 }
 #define acpi_irq_init acpi_irq_init
 
+static inline int nr_legacy_irqs(void)
+{
+	return 0;
+}
+
 #endif

@@ -39,6 +39,7 @@
 #include <asm/irq.h>
 #include <asm/idle.h>
 #include <asm/io_apic.h>
+#include <asm/i8259.h>
 #include <asm/xen/pci.h>
 #include <xen/page.h>
 #endif

@@ -420,7 +421,7 @@ static int __must_check xen_allocate_irq
 		return xen_allocate_irq_dynamic();
 
 	/* Legacy IRQ descriptors are already allocated by the arch. */
-	if (gsi < NR_IRQS_LEGACY)
+	if (gsi < nr_legacy_irqs())
 		irq = gsi;
 	else
 		irq = irq_alloc_desc_at(gsi, -1);

@@ -446,7 +447,7 @@ static void xen_free_irq(unsigned irq)
 	kfree(info);
 
 	/* Legacy IRQ descriptors are managed by the arch. */
-	if (irq < NR_IRQS_LEGACY)
+	if (irq < nr_legacy_irqs())
 		return;
 
 	irq_free_desc(irq);

Patches currently in stable-queue which might be from [email protected] are

queue-4.3/xen-events-always-allocate-legacy-interrupts-on-pv-guests.patch queue-4.3/x86-cpu-fix-smap-check-in-pvops-environments.patch