diff options
| -rw-r--r-- | arch/x86/kernel/cpu/perf_event.c | 16 |
1 files changed, 15 insertions, 1 deletions
diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c index 2eca19422454..4f7001f28936 100644 --- a/arch/x86/kernel/cpu/perf_event.c +++ b/arch/x86/kernel/cpu/perf_event.c @@ -190,6 +190,7 @@ static bool check_hw_exists(void) u64 val, val_fail, val_new= ~0; int i, reg, reg_fail, ret = 0; int bios_fail = 0; + int reg_safe = -1; /* * Check to see if the BIOS enabled any of the counters, if so @@ -204,6 +205,8 @@ static bool check_hw_exists(void) bios_fail = 1; val_fail = val; reg_fail = reg; + } else { + reg_safe = i; } } @@ -222,11 +225,22 @@ static bool check_hw_exists(void) } /* + * If all the counters are enabled, the below test will always + * fail. The tools will also become useless in this scenario. + * Just fail and disable the hardware counters. + */ + + if (reg_safe == -1) { + reg = reg_safe; + goto msr_fail; + } + + /* * Read the current value, change it and read it back to see if it * matches, this is needed to detect certain hardware emulators * (qemu/kvm) that don't trap on the MSR access and always return 0s. */ - reg = x86_pmu_event_addr(0); + reg = x86_pmu_event_addr(reg_safe); if (rdmsrl_safe(reg, &val)) goto msr_fail; val ^= 0xffffUL; |