linux-kernel - Re: [PATCH v2 2/3] Mutually exclude cpu online and suspend/hibernate

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Date:	Wed, 19 Oct 2011 22:59:59 +0530
From:	"Srivatsa S. Bhat" <srivatsa.bhat@...ux.vnet.ibm.com>
To:	Borislav Petkov <bp@...64.org>
CC:	Tejun Heo <tj@...nel.org>, "Rafael J. Wysocki" <rjw@...k.pl>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	"pavel@....cz" <pavel@....cz>,
	"len.brown@...el.com" <len.brown@...el.com>,
	"mingo@...e.hu" <mingo@...e.hu>,
	"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
	"suresh.b.siddha@...el.com" <suresh.b.siddha@...el.com>,
	"lucas.demarchi@...fusion.mobi" <lucas.demarchi@...fusion.mobi>,
	"rusty@...tcorp.com.au" <rusty@...tcorp.com.au>,
	"rdunlap@...otime.net" <rdunlap@...otime.net>,
	"vatsa@...ux.vnet.ibm.com" <vatsa@...ux.vnet.ibm.com>,
	"ashok.raj@...el.com" <ashok.raj@...el.com>,
	"tigran@...azian.fsnet.co.uk" <tigran@...azian.fsnet.co.uk>,
	"tglx@...utronix.de" <tglx@...utronix.de>,
	"hpa@...or.com" <hpa@...or.com>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>
Subject: Re: [PATCH v2 2/3] Mutually exclude cpu online and suspend/hibernate

On 10/13/2011 10:59 PM, Srivatsa S. Bhat wrote:
> On 10/13/2011 10:31 PM, Borislav Petkov wrote:
>> On Thu, Oct 13, 2011 at 12:06:02PM -0400, Tejun Heo wrote:
>>> I hate to sound like a broken recorder but the above patch isn't
>>> strictly correct for hot-swap cases, right?
>>
>> hpa is working on a ucode loading solution which will take care of your
>> hotswap case too.
>>
> 
> Tejun, I have written a patch below (untested) that does what you said.
> So Boris, hpa's work would make such a patch unnecessary is it?
> 

I have posted this patch (tested/corrected and with changelog), in case
it is useful/necessary. Link: https://lkml.org/lkml/2011/10/19/295

> ---
> 
>  arch/x86/kernel/microcode_core.c |   33 +++++++++++++++++++++++++++++++++
>  1 files changed, 33 insertions(+), 0 deletions(-)
> 
> diff --git a/arch/x86/kernel/microcode_core.c b/arch/x86/kernel/microcode_core.c
> index f924280..849ae2d 100644
> --- a/arch/x86/kernel/microcode_core.c
> +++ b/arch/x86/kernel/microcode_core.c
> @@ -155,6 +155,27 @@ static int collect_cpu_info(int cpu)
>  	return ret;
>  }
>  
> +/*
> + * Compare the microcode revision that the kernel has in memory
> + * for this cpu and the microcode revision that we need to apply
> + * on this cpu. If they match, return 0, else return -1.
> + */
> +static int compare_cpu_with_microcode(int cpu)
> +{
> +	struct ucode_cpu_info *uci_mem = ucode_cpu_info + cpu;
> +	struct ucode_cpu_info uci_cpu;
> +	int ret;
> +
> +	ret = collect_cpu_info_on_target(cpu, &uci_cpu->cpu_sig);
> +	if(!ret) {
> +		if (!(uci_mem->cpu_sig->sig == uci_cpu->cpu_sig->sig &&
> +		      uci_mem->cpu_sig->pf == uci_cpu->cpu_sig->pf &&
> +		      uci_mem->cpu_sig->rev == uci_cpu->cpu_sig->rev))
> +			ret = -1;
> +	}
> +	return ret;
> +}
> +
>  struct apply_microcode_ctx {
>  	int err;
>  };
> @@ -397,6 +418,18 @@ static enum ucode_state microcode_update_cpu(int cpu)
>  	struct ucode_cpu_info *uci = ucode_cpu_info + cpu;
>  	enum ucode_state ustate;
>  
> +	/*
> +	 * If the CPU on which we are going to update the
> +	 * microcode and the microcode which we currently
> +	 * have in kernel memory are incompatible, then
> +	 * invalidate the microcode that we have (and also
> +	 * free its memory), so that we can get the required
> +	 * microcode afresh.
> +	 */
> +	if (compare_cpu_with_microcode(cpu)) {
> +		microcode_fini_cpu(cpu);
> +	}
> +
>  	if (uci->valid)
>  		ustate = microcode_resume_cpu(cpu);
>  	else
> 
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