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authorStephane Eranian <eranian@google.com>2012-08-24 15:34:34 +0200
committerIngo Molnar <mingo@kernel.org>2012-08-27 08:48:19 +0200
commite3e45c01ae690e65f2650e5288b9af802e95a136 (patch)
tree8a1032f058653b75bd0d4c975e93e1c4316a44db /arch/x86
parent9acb172543aecb783e2e1e53e3f447d4c0f5c150 (diff)
perf/x86: Fix microcode revision check for SNB-PEBS
The following patch makes the microcode update code path actually invoke the perf_check_microcode() function and thus potentially renabling SNB PEBS. By default, CONFIG_MICROCODE_OLD_INTERFACE is forced to Y in arch/x86/Kconfig. There is no way to disable this. That means that the code path used in arch/x86/kernel/microcode_core.c did not include the call to perf_check_microcode(). Thus, even though the microcode was updated to a version that fixes the SNB PEBS problem, perf_event would still return EOPNOTSUPP when enabling precise sampling. This patch simply adds a call to perf_check_microcode() in the call path used when OLD_INTERFACE=y. Signed-off-by: Stephane Eranian <eranian@google.com> Acked-by: Borislav Petkov <borislav.petkov@amd.com> Cc: peterz@infradead.org Cc: andi@firstfloor.org Link: http://lkml.kernel.org/r/20120824133434.GA8014@quad Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86')
-rw-r--r--arch/x86/kernel/microcode_core.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/arch/x86/kernel/microcode_core.c b/arch/x86/kernel/microcode_core.c
index 4873e62db6a1..9e5bcf1e2376 100644
--- a/arch/x86/kernel/microcode_core.c
+++ b/arch/x86/kernel/microcode_core.c
@@ -225,6 +225,9 @@ static ssize_t microcode_write(struct file *file, const char __user *buf,
if (do_microcode_update(buf, len) == 0)
ret = (ssize_t)len;
+ if (ret > 0)
+ perf_check_microcode();
+
mutex_unlock(&microcode_mutex);
put_online_cpus();