On 10/12/2016 05:16 AM, Grzegorz Andrejczuk wrote:
> @@ -211,6 +219,25 @@ static void early_init_intel(struct cpuinfo_x86 *c)
> }
>
> check_mpx_erratum(c);
> +
> + /*
> + * Setting ring 3 MONITOR/MWAIT for all threads
> + * when CPU is Xeon Phi Family x200
> + * This can be disabled with phir3mwait=disable cmdline switch.
> + * We preserve the reserved values and set only 2nd bit.
> + * Ref:
> + *
> https://software.intel.com/en-us/blogs/2016/10/06/intel-xeon-phi-product-family-x200-knl-user-mode-ring-3-monitor-and-mwait
> + */
> + if (c->x86 == 6 &&
> + c->x86_model == INTEL_FAM6_XEON_PHI_KNL &&
> + phir3mwait) {
> + u64 prev;
> +
> + rdmsrl(MSR_PHI_MISC_THD_FEATURE, prev);
> + if ((prev & MSR_PHI_MISC_THD_FEATURE_R3MWAIT) == 0)
> + wrmsrl(MSR_PHI_MISC_THD_FEATURE,
> + prev | MSR_PHI_MISC_THD_FEATURE_R3MWAIT);
> + }
> }
I'd really prefer that we put hunks like this into helpers just like the
nice check_mpx_erratum(). I know early_init_intel() looks a lot like
what you have here, but I think a little:
probe_xeon_phi_mwait()
would be a lot nicer.
BTW, this hunk totally indicates how badly named 'phir3mwait' is. Could
you please give it a sane name like 'phi_r3_mwait_disabled'?
