Re: [PATCH v9 13/17] x86/split_lock: Disable split lock detection by kernel parameter "nosplit_lock_detect"

Thomas Gleixner
2019-06-26T20:35:16Z

On Tue, 18 Jun 2019, Fenghua Yu wrote:
>
> static void split_lock_update_msr(void)
> {
> - /* Enable split lock detection */
> - this_cpu_or(msr_test_ctl_cached, MSR_TEST_CTL_SPLIT_LOCK_DETECT);
> + if (split_lock_detect_enabled) {
> + /* Enable split lock detection */
> + this_cpu_or(msr_test_ctl_cached, MSR_TEST_CTL_SPLIT_LOCK_DETECT);
> + } else {
> + /* Disable split lock detection */

Could you please comment the non obvious things and not the obvious ones?

> + this_cpu_and(msr_test_ctl_cached, ~MSR_TEST_CTL_SPLIT_LOCK_DETECT);

It's entirely clear that the if (enabled) path enables it or am I missing
something?

Thanks,

tglx