diff options
| -rw-r--r-- | arch/x86/kernel/cpu/perf_event.c | 48 |
1 files changed, 42 insertions, 6 deletions
diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c index 817d2b195e8e..ce27c547fe78 100644 --- a/arch/x86/kernel/cpu/perf_event.c +++ b/arch/x86/kernel/cpu/perf_event.c @@ -375,15 +375,53 @@ static void release_pmc_hardware(void) {} static bool check_hw_exists(void) { u64 val, val_new = 0; - int ret = 0; + int i, reg, ret = 0; + + /* + * Check to see if the BIOS enabled any of the counters, if so + * complain and bail. + */ + for (i = 0; i < x86_pmu.num_counters; i++) { + reg = x86_pmu.eventsel + i; + ret = rdmsrl_safe(reg, &val); + if (ret) + goto msr_fail; + if (val & ARCH_PERFMON_EVENTSEL_ENABLE) + goto bios_fail; + } + + if (x86_pmu.num_counters_fixed) { + reg = MSR_ARCH_PERFMON_FIXED_CTR_CTRL; + ret = rdmsrl_safe(reg, &val); + if (ret) + goto msr_fail; + for (i = 0; i < x86_pmu.num_counters_fixed; i++) { + if (val & (0x03 << i*4)) + goto bios_fail; + } + } + /* + * Now write a value 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. + */ val = 0xabcdUL; - ret |= checking_wrmsrl(x86_pmu.perfctr, val); + ret = checking_wrmsrl(x86_pmu.perfctr, val); ret |= rdmsrl_safe(x86_pmu.perfctr, &val_new); if (ret || val != val_new) - return false; + goto msr_fail; return true; + +bios_fail: + printk(KERN_CONT "Broken BIOS detected, using software events only.\n"); + printk(KERN_ERR FW_BUG "the BIOS has corrupted hw-PMU resources (MSR %x is %Lx)\n", reg, val); + return false; + +msr_fail: + printk(KERN_CONT "Broken PMU hardware detected, using software events only.\n"); + return false; } static void reserve_ds_buffers(void); @@ -1378,10 +1416,8 @@ int __init init_hw_perf_events(void) pmu_check_apic(); /* sanity check that the hardware exists or is emulated */ - if (!check_hw_exists()) { - pr_cont("Broken PMU hardware detected, software events only.\n"); + if (!check_hw_exists()) return 0; - } pr_cont("%s PMU driver.\n", x86_pmu.name); |
