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| author | Tony Lindgren <tony@atomide.com> | 2012-11-09 14:58:01 -0800 |
|---|---|---|
| committer | Tony Lindgren <tony@atomide.com> | 2012-11-09 14:58:01 -0800 |
| commit | edf8dde393f879fc2d8c22d4bc01ff8d37b80e1a (patch) | |
| tree | 61425adc8b2059a9c12a3ce66ba7361fea1b0bb3 /arch/x86/kernel/cpu/perf_event.c | |
| parent | 6ba54ab4a49bbad736b0254aa6bdf0cb83013815 (diff) | |
| parent | 3d70f8c617a436c7146ecb81df2265b4626dfe89 (diff) | |
Merge branch 'linus' into omap-for-v3.8/cleanup-headers-prepare-multiplatform-v3
Diffstat (limited to 'arch/x86/kernel/cpu/perf_event.c')
| -rw-r--r-- | arch/x86/kernel/cpu/perf_event.c | 10 |
1 files changed, 6 insertions, 4 deletions
diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c index 3373f84d1397..4a3374e61a93 100644 --- a/arch/x86/kernel/cpu/perf_event.c +++ b/arch/x86/kernel/cpu/perf_event.c @@ -208,12 +208,14 @@ static bool check_hw_exists(void) } /* - * 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. + * 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. */ - val = 0xabcdUL; reg = x86_pmu_event_addr(0); + if (rdmsrl_safe(reg, &val)) + goto msr_fail; + val ^= 0xffffUL; ret = wrmsrl_safe(reg, val); ret |= rdmsrl_safe(reg, &val_new); if (ret || val != val_new) |