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SubjectRe: [PATCH v17] x86/split_lock: Enable split lock detection by kernel
Date
"Luck, Tony" <tony.luck@intel.com> writes:
> +static bool __sld_msr_set(bool on)
> +{
> + u64 test_ctrl_val;
> +
> + if (rdmsrl_safe(MSR_TEST_CTRL, &test_ctrl_val))
> + return false;
> +
> + if (on)
> + test_ctrl_val |= MSR_TEST_CTRL_SPLIT_LOCK_DETECT;
> + else
> + test_ctrl_val &= ~MSR_TEST_CTRL_SPLIT_LOCK_DETECT;
> +
> + return !wrmsrl_safe(MSR_TEST_CTRL, test_ctrl_val);
> +}
> +
> +static void split_lock_init(void)
> +{
> + if (sld_state == sld_off)
> + return;
> +
> + if (__sld_msr_set(true))
> + return;
> +
> + /*
> + * If this is anything other than the boot-cpu, you've done
> + * funny things and you get to keep whatever pieces.
> + */
> + pr_warn("MSR fail -- disabled\n");
> + __sld_msr_set(sld_off);

This one is pretty pointless. If the rdmsrl or the wrmsrl failed, then
the next attempt is going to fail too. Aside of that sld_off would be not
really the right argument value here. I just zap that line.

Thanks,

tglx

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