From: Jiri Olsa jolsa@redhat.com
[ Upstream commit d0e1a507bdc761a14906f03399d933ea639a1756 ]
Tom Vaden reported false failure of the check_msr() function, because some servers can do POST tracing and enable LBR tracing during bootup.
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@hpe.com Signed-off-by: Jiri Olsa jolsa@kernel.org Signed-off-by: Peter Zijlstra (Intel) peterz@infradead.org Acked-by: Tom Vaden tom.vaden@hpe.com Cc: Alexander Shishkin alexander.shishkin@linux.intel.com Cc: Arnaldo Carvalho de Melo acme@kernel.org Cc: Liang Kan kan.liang@linux.intel.com Cc: Linus Torvalds torvalds@linux-foundation.org Cc: Namhyung Kim namhyung@kernel.org Cc: Peter Zijlstra peterz@infradead.org Cc: Thomas Gleixner tglx@linutronix.de Link: https://lkml.kernel.org/r/20190616141313.GD2500@krava [ Readability edits. ] Signed-off-by: Ingo Molnar mingo@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- 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 82dad001d1ea..a50e182c38b6 100644 --- a/arch/x86/events/intel/core.c +++ b/arch/x86/events/intel/core.c @@ -19,6 +19,7 @@ #include <asm/intel-family.h> #include <asm/apic.h> #include <asm/cpu_device_id.h> +#include <asm/hypervisor.h>
#include "../perf_event.h"
@@ -3927,6 +3928,13 @@ 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