[Xen-devel] [PATCH 5/6] xen/hvm kexec: unregister timer interrupt during reboot

[Olaf Hering <olaf@xxxxxxxxx>]

The kexec kernel will crash because the timer interrupt is already
registerd with EVTCHNOP_bind_virq.  Unbind the event channel during
shutdown so that the kexec kernel can reregister the interrupt.

Signed-off-by: Olaf Hering <olaf@xxxxxxxxx>

---
 arch/x86/xen/time.c |   27 ++++++++++++++++++++++++---
 1 file changed, 24 insertions(+), 3 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 +14,7 @@
 #include <linux/kernel_stat.h>
 #include <linux/math64.h>
 #include <linux/gfp.h>
+#include <linux/syscore_ops.h>
 
 #include <asm/pvclock.h>
 #include <asm/xen/hypervisor.h>
@@ -405,12 +406,20 @@ 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;
-       BUG_ON(cpu == 0);
        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)
+{
+       BUG_ON(cpu == 0);
+       xen_unbind_timer(cpu);
 }
 
 void xen_setup_cpu_clockevents(void)
@@ -478,6 +487,17 @@ void __init xen_init_time_ops(void)
 }
 
 #ifdef CONFIG_XEN_PVHVM
+static void xen_hvmtimer_shutdown(void)
+{
+       int cpu;
+       for_each_online_cpu(cpu)
+               xen_unbind_timer(cpu);
+}
+
+static struct syscore_ops xen_hvmtimer_syscore_ops = {
+       .shutdown = xen_hvmtimer_shutdown,
+};
+
 static void xen_hvm_setup_cpu_clockevents(void)
 {
        int cpu = smp_processor_id();
@@ -506,5 +526,6 @@ 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


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