linux-kernel - Re: [PATCH 06/32] x86/intel_rdt: Hot cpu support for Cache Allocation

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Date:	Wed, 13 Jul 2016 17:40:59 -0700
From:	David Carrillo-Cisneros <davidcc@...gle.com>
To:	Fenghua Yu <fenghua.yu@...el.com>
Cc:	Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...e.hu>,
	"H. Peter Anvin" <h.peter.anvin@...el.com>,
	Tony Luck <tony.luck@...el.com>, Tejun Heo <tj@...nel.org>,
	Borislav Petkov <bp@...e.de>,
	Stephane Eranian <eranian@...gle.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Marcelo Tosatti <mtosatti@...hat.com>,
	Ravi V Shankar <ravi.v.shankar@...el.com>,
	Vikas Shivappa <vikas.shivappa@...ux.intel.com>,
	Sai Prakhya <sai.praneeth.prakhya@...el.com>,
	linux-kernel <linux-kernel@...r.kernel.org>, x86 <x86@...nel.org>
Subject: Re: [PATCH 06/32] x86/intel_rdt: Hot cpu support for Cache Allocation

> +static inline void intel_rdt_cpu_start(int cpu)
> +{
> +       struct intel_pqr_state *state = &per_cpu(pqr_state, cpu);
> +
> +       state->closid = 0;
> +       mutex_lock(&rdt_group_mutex);
> +       if (rdt_cpumask_update(cpu))
> +               smp_call_function_single(cpu, cbm_update_msrs, NULL, 1);
> +       mutex_unlock(&rdt_group_mutex);

what happens if cpu's with a cache_id not available at boot comes online?