[tip:perf/core] perf/x86/intel: Disable check_msr for real HW

From: tip-bot for Jiri Olsa
Date: Mon Jun 17 2019 - 10:46:33 EST

Commit-ID: d0e1a507bdc761a14906f03399d933ea639a1756
Gitweb: https://git.kernel.org/tip/d0e1a507bdc761a14906f03399d933ea639a1756
Author: Jiri Olsa <jolsa@xxxxxxxxxx>
AuthorDate: Sun, 16 Jun 2019 16:13:13 +0200
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Mon, 17 Jun 2019 12:36:24 +0200

perf/x86/intel: Disable check_msr for real HW

Tom Vaden reported false failure of the check_msr() function, because
some servers can do POST tracing and enable LBR tracing during

Kan confirmed that check_msr patch was to fix a bug report in
guest, so it's ok to disable it for real HW.

Reported-by: Tom Vaden <tom.vaden@xxxxxxx>
Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Acked-by: Tom Vaden <tom.vaden@xxxxxxx>
Cc: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Liang Kan <kan.liang@xxxxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Link: 20190616141313.GD2500@krava">https://lkml.kernel.org/r/20190616141313.GD2500@krava
[ Readability edits. ]
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
arch/x86/events/intel/core.c | 8 ++++++++
1 file changed, 8 insertions(+)

diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
index 5e6ae481dee7..bda450ff51ee 100644
--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -20,6 +20,7 @@
#include <asm/intel-family.h>
#include <asm/apic.h>
#include <asm/cpu_device_id.h>
+#include <asm/hypervisor.h>

#include "../perf_event.h"

@@ -4050,6 +4051,13 @@ static bool check_msr(unsigned long msr, u64 mask)
u64 val_old, val_new, val_tmp;

+ /*
+ * Disable the check for real HW, so we don't
+ * mess with potentionaly enabled registers:
+ */
+ if (hypervisor_is_type(X86_HYPER_NATIVE))
+ return true;
* Read the current value, change it and read it back to see if it
* matches, this is needed to detect certain hardware emulators