Fix the NMI watchdog on Intel CoreDuo processor where the kernel would
get stuck during boot.  The issue is related to errata AE49, where the
PERFEVTSEL1 counter does not have a working enable bit.  Thus it is not
possible to use it for NMI.

The patch creates a dedicated wd_ops for CoreDuo which falls back to
using PERFEVTSEL0.  The other Intel processors supporting the
architectural PMU will keep on using PERFEVTSEL1 as this allows other
subsystems, such as perfmon, to use PERFEVTSEL0 for PEBS monitoring in
particular.  Bug initially reported by Daniel Walker.

AK: Added comments
Signed-off-by: NStephane Eranian <eranian@hpl.hp.com>
Signed-off-by: NAndi Kleen <ak@suse.de>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The performance counters on K7 are only 48 bits wide, so using bit 63 to
check if the counter overflowed is wrong. Let's use bit 47 instead.
Signed-off-by: NBjörn Steinbrink <B.Steinbrink@gmx.de>
Cc: Don Zickus <dzickus@redhat.com>
Signed-off-by: NAndi Kleen <ak@suse.de>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

I got an oops while booting a 32bit kernel on KVM because it doesn't
implement performance counters used by the NMI watchdog. Handle this
case.

Cc: Avi Kivity <avi@qumranet.com>
Signed-off-by: NAndi Kleen <ak@suse.de>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The Intel PerfMon NMI watchdog reserves the first performance counter,
but uses the second one. Make it correctly reserve the second one.
Signed-off-by: NBjörn Steinbrink <B.Steinbrink@gmx.de>
Signed-off-by: NAndi Kleen <ak@suse.de>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

With this change it works again when the nmi watchdog is disabled.
Signed-off-by: NAndi Kleen <ak@suse.de>
Cc: Björn Steinbrink <B.Steinbrink@gmx.de>
Cc: Stephane Eranian <eranian@hpl.hp.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Fix oops triggered during: echo 0 > /proc/sys/kernel/nmi_watchdog

The culprit seems to be 09198e68:
[PATCH] i386: Clean up NMI watchdog code

In two places, the parameters to release_{evntsel,perfctr}_nmi
got interchanged during the cleanup.

Fix interchanged parameters to release_{evntsel,perfctr}_nmi.
Signed-off-by: NBjörn Steinbrink <B.Steinbrink@gmx.de>
Cc: Stephane Eranian <eranian@hpl.hp.com>
Cc: Andi Kleen <ak@suse.de>
Cc: Michal Piotrowski <michal.k.k.piotrowski@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

When disabled through /proc/sys/kernel/nmi_watchdog, the NMI watchdog uses the
stop() method directly, which does not decrement the activity counter, leading
to a BUG().  Use the wrapper function instead to fix that.
Signed-off-by: NBjörn Steinbrink <B.Steinbrink@gmx.de>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

At system boot time, the NMI watchdog no longer reserved its MSRs, allowing
other subsystems to mess with them.  Fix that.
Signed-off-by: NBjörn Steinbrink <B.Steinbrink@gmx.de>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

- Introduce a wd_ops structure
- Convert the various nmi watchdogs over to it
- This allows to split the perfctr reservation from the watchdog
setup cleanly.
- Do perfctr reservation globally as it should have always been
- Remove dead code referenced only by unused EXPORT_SYMBOLs
Signed-off-by: NAndi Kleen <ak@suse.de>