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| author | Catalin Marinas <catalin.marinas@arm.com> | 2012-11-05 14:58:32 +0000 |
|---|---|---|
| committer | Catalin Marinas <catalin.marinas@arm.com> | 2012-11-05 14:58:32 +0000 |
| commit | 3fd9396af83a1e69eaf9ebb573207431d8f265b6 (patch) | |
| tree | f221f5777695de71ea97423c67438bca1746e26c /arch/x86/kernel/cpu/perf_event.c | |
| parent | e3978cded41dc7b364e74037f56d6bc558c11fd7 (diff) | |
| parent | 3d70f8c617a436c7146ecb81df2265b4626dfe89 (diff) | |
Merge tag 'v3.7-rc4' into upstream-master
Linux 3.7-rc4
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) |