[PATCH 04/11] xen/hvm kexec: unregister timer interrupt during reboot

[Olaf Hering <olaf@aepfle.de>]

[-- Attachment #1: xen.syscore_ops.unbind.timer-irq.patch --]
[-- Type: text/plain, Size: 1921 bytes --]

Unregister the timer interrupt during kexec, otherwise the kexec kernel will
run into the BUG() in bind_virq_to_irq() when trying to bind to the
still registered virq.

v2:
 use kexec_is_loaded() function

Signed-off-by: Olaf Hering <olaf@aepfle.de>

---
 arch/x86/xen/time.c |   30 ++++++++++++++++++++++++++++--
 1 file changed, 28 insertions(+), 2 deletions(-)

Index: linux-3.0/arch/x86/xen/time.c
===================================================================
--- linux-3.0.orig/arch/x86/xen/time.c
+++ linux-3.0/arch/x86/xen/time.c
@@ -14,6 +14,8 @@
 #include <linux/kernel_stat.h>
 #include <linux/math64.h>
 #include <linux/gfp.h>
+#include <linux/kexec.h>
+#include <linux/syscore_ops.h>
 
 #include <asm/pvclock.h>
 #include <asm/xen/hypervisor.h>
@@ -405,11 +407,19 @@ void xen_setup_timer(int cpu)
 	evt->irq = irq;
 }
 
-void xen_teardown_timer(int cpu)
+static void xen_unbind_timer(int cpu)
 {
 	struct clock_event_device *evt;
 	evt = &per_cpu(xen_clock_events, cpu);
-	unbind_from_irqhandler(evt->irq, NULL);
+	if (evt->irq >= 0) {
+		unbind_from_irqhandler(evt->irq, NULL);
+		evt->irq = -1;
+	}
+}
+
+void xen_teardown_timer(int cpu)
+{
+	xen_unbind_timer(cpu);
 }
 
 void xen_setup_cpu_clockevents(void)
@@ -477,6 +487,21 @@ void __init xen_init_time_ops(void)
 }
 
 #ifdef CONFIG_XEN_PVHVM
+static void xen_hvm_timer_shutdown(void)
+{
+	int cpu;
+
+	if (!kexec_is_loaded())
+		return;
+
+	for_each_online_cpu(cpu)
+		xen_unbind_timer(cpu);
+}
+
+static struct syscore_ops xen_hvmtimer_syscore_ops = {
+	.shutdown = xen_hvm_timer_shutdown,
+};
+
 static void xen_hvm_setup_cpu_clockevents(void)
 {
 	int cpu = smp_processor_id();
@@ -505,5 +530,6 @@ void __init xen_hvm_init_time_ops(void)
 	x86_platform.calibrate_tsc = xen_tsc_khz;
 	x86_platform.get_wallclock = xen_get_wallclock;
 	x86_platform.set_wallclock = xen_set_wallclock;
+	register_syscore_ops(&xen_hvmtimer_syscore_ops);
 }
 #endif