61 lines
2.2 KiB
Diff
61 lines
2.2 KiB
Diff
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# Commit 2a16fcd5ba0244fef764886211452acc69c0ed00
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# Date 2013-11-22 14:48:12 +0100
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# Author David Vrabel <david.vrabel@citrix.com>
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# Committer Jan Beulich <jbeulich@suse.com>
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x86/crash: disable the watchdog NMIs on the crashing cpu
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nmi_shootdown_cpus() is called during a crash to park all the other
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CPUs. This changes the NMI trap handlers which means there's no point
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in having the watchdog still running.
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This also disables the watchdog before executing any crash kexec image
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and prevents the image from receiving unexpected NMIs.
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Signed-off-by: David Vrabel <david.vrabel@citrix.com>
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PVOps Linux as a kexec image shoots itself in the foot otherwise.
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On a Core2 system, Linux declares a firmware bug and tries to invert some bits
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in the performance counter register. It ends up setting the number of retired
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instructions to generate another NMI to fewer instructions than the NMI
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interrupt path itself, and ceases to make any useful progress.
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The call to disable_lapic_nmi_watchdog() must be this late into the kexec path
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to be sure that this cpu is the one which will execute the kexec image.
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Otherwise there are race conditions where the NMIs might be disabled on the
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wrong cpu, resulting in the kexec image still receiving NMIs.
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Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
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--- a/xen/arch/x86/crash.c
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+++ b/xen/arch/x86/crash.c
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@@ -117,6 +117,7 @@ static void nmi_shootdown_cpus(void)
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unsigned long msecs;
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int i, cpu = smp_processor_id();
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+ disable_lapic_nmi_watchdog();
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local_irq_disable();
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crashing_cpu = cpu;
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--- a/xen/arch/x86/nmi.c
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+++ b/xen/arch/x86/nmi.c
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@@ -165,7 +165,7 @@ static void nmi_timer_fn(void *unused)
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set_timer(&this_cpu(nmi_timer), NOW() + MILLISECS(1000));
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}
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-static void disable_lapic_nmi_watchdog(void)
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+void disable_lapic_nmi_watchdog(void)
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{
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if (nmi_active <= 0)
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return;
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--- a/xen/include/asm-x86/apic.h
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+++ b/xen/include/asm-x86/apic.h
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@@ -200,6 +200,7 @@ extern void smp_local_timer_interrupt (s
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extern void setup_boot_APIC_clock (void);
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extern void setup_secondary_APIC_clock (void);
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extern void setup_apic_nmi_watchdog (void);
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+extern void disable_lapic_nmi_watchdog(void);
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extern int reserve_lapic_nmi(void);
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extern void release_lapic_nmi(void);
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extern void self_nmi(void);
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