From: Jiri Olsa <jolsa@xxxxxxxxxx> [ 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@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: https://lkml.kernel.org/r/20190616141313.GD2500@krava [ Readability edits. ] Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@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 b6cae65aa7ef..f0c14665893b 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" @@ -4054,6 +4055,13 @@ 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 -- 2.20.1
