From mboxrd@z Thu Jan  1 00:00:00 1970
From: Andrew Cooper <andrew.cooper3@citrix.com>
Subject: Re: [PATCH 2 of 7] KEXEC BUG: nmi_shootdown_cpus doesn't
	look after the interrupt flag [Reformatted]
Date: Wed, 15 Jun 2011 12:01:09 +0100
Message-ID: <4DF890F5.9090304@citrix.com>
References: <CA1CEC81.1C266%keir.xen@gmail.com>
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To: Keir Fraser <keir.xen@gmail.com>
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Reformatted as per Keir's suggestion.

~Andrew

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KEXEC BUG: nmi_shootdown_cpus doesn't look after the interrupt flag

nmi_shootdown_cpus is part of the kexec path, coming from a panic, and
as such can be called both with interrupts enabled or disabled. We
really dont want to accidentally set IF.

Therefore, use save/restore in preference to disable/enable.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>

diff -r a6f5c3a474e3 xen/arch/x86/crash.c
--- a/xen/arch/x86/crash.c	Wed Jun 15 11:47:12 2011 +0100
+++ b/xen/arch/x86/crash.c	Wed Jun 15 11:57:12 2011 +0100
@@ -57,7 +57,7 @@ static void nmi_shootdown_cpus(void)
 {
     unsigned long msecs;
 
-    local_irq_disable();
+    BUG_ON(local_irq_is_enabled());
 
     crashing_cpu = smp_processor_id();
     local_irq_count(crashing_cpu) = 0;
@@ -79,14 +79,14 @@ static void nmi_shootdown_cpus(void)
 
     __stop_this_cpu();
     disable_IO_APIC();
-
-    local_irq_enable();
 }
 
 void machine_crash_shutdown(void)
 {
     crash_xen_info_t *info;
 
+    local_irq_disable();
+
     nmi_shootdown_cpus();
 
     info = kexec_crash_save_info();

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