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authorNicholas Piggin <npiggin@gmail.com>2017-07-12 14:35:52 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2017-07-12 16:26:02 -0700
commit2104180a53698df5aec35aed5f840a26ade0551d (patch)
tree72fcbf52fd53a333282de9103197c04576025c54 /arch/powerpc/kernel/kvm.c
parenta10a842ff81a7e3810817b3b04e4c432b6191e21 (diff)
downloadop-kernel-dev-2104180a53698df5aec35aed5f840a26ade0551d.zip
op-kernel-dev-2104180a53698df5aec35aed5f840a26ade0551d.tar.gz
powerpc/64s: implement arch-specific hardlockup watchdog
Implement an arch-speicfic watchdog rather than use the perf-based hardlockup detector. The new watchdog takes the soft-NMI directly, rather than going through perf. Perf interrupts are to be made maskable in future, so that would prevent the perf detector from working in those regions. Additionally, implement a SMP based detector where all CPUs watch one another by pinging a shared cpumask. This is because powerpc Book3S does not have a true periodic local NMI, but some platforms do implement a true NMI IPI. If a CPU is stuck with interrupts hard disabled, the soft-NMI watchdog does not work, but the SMP watchdog will. Even on platforms without a true NMI IPI to get a good trace from the stuck CPU, other CPUs will notice the lockup sufficiently to report it and panic. [npiggin@gmail.com: honor watchdog disable at boot/hotplug] Link: http://lkml.kernel.org/r/20170621001346.5bb337c9@roar.ozlabs.ibm.com [npiggin@gmail.com: fix false positive warning at CPU unplug] Link: http://lkml.kernel.org/r/20170630080740.20766-1-npiggin@gmail.com [akpm@linux-foundation.org: coding-style fixes] Link: http://lkml.kernel.org/r/20170616065715.18390-6-npiggin@gmail.com Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Reviewed-by: Don Zickus <dzickus@redhat.com> Tested-by: Babu Moger <babu.moger@oracle.com> [sparc] Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch/powerpc/kernel/kvm.c')
-rw-r--r--arch/powerpc/kernel/kvm.c7
1 files changed, 7 insertions, 0 deletions
diff --git a/arch/powerpc/kernel/kvm.c b/arch/powerpc/kernel/kvm.c
index 9ad37f8..1086ea3 100644
--- a/arch/powerpc/kernel/kvm.c
+++ b/arch/powerpc/kernel/kvm.c
@@ -25,6 +25,7 @@
#include <linux/kvm_para.h>
#include <linux/slab.h>
#include <linux/of.h>
+#include <linux/nmi.h> /* hardlockup_detector_disable() */
#include <asm/reg.h>
#include <asm/sections.h>
@@ -718,6 +719,12 @@ static __init void kvm_free_tmp(void)
static int __init kvm_guest_init(void)
{
+ /*
+ * The hardlockup detector is likely to get false positives in
+ * KVM guests, so disable it by default.
+ */
+ hardlockup_detector_disable();
+
if (!kvm_para_available())
goto free_tmp;
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