linux-kernel - Re: [PATCH 4/7] x86/intel_rdt: Implement scheduling support for Intel RDT

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Mon, 18 May 2015 11:01:26 -0700 (PDT)
From:	Vikas Shivappa <vikas.shivappa@...el.com>
To:	Thomas Gleixner <tglx@...utronix.de>
cc:	Vikas Shivappa <vikas.shivappa@...ux.intel.com>,
	vikas.shivappa@...el.com, x86@...nel.org,
	linux-kernel@...r.kernel.org, hpa@...or.com, mingo@...nel.org,
	tj@...nel.org, peterz@...radead.org, matt.fleming@...el.com,
	will.auld@...el.com, peter.zijlstra@...el.com,
	h.peter.anvin@...el.com, kanaka.d.juvva@...el.com,
	mtosatti@...hat.com
Subject: Re: [PATCH 4/7] x86/intel_rdt: Implement scheduling support for
 Intel RDT



On Fri, 15 May 2015, Thomas Gleixner wrote:

> On Mon, 11 May 2015, Vikas Shivappa wrote:
>>  struct rdt_subsys_info {
>>  	/* Clos Bitmap to keep track of available CLOSids.*/
>> @@ -24,6 +30,11 @@ struct clos_cbm_map {
>>  	unsigned int clos_refcnt;
>>  };
>>
>> +static inline bool rdt_enabled(void)
>> +{
>> +	return static_key_false(&rdt_enable_key);
>
> So again, why this useless helper function for a single call site?
>
>> +static inline void intel_rdt_sched_in(void)
>> +{
>> +	if (rdt_enabled())
>> +		__rdt_sched_in();
>> +}
>
>> +void __rdt_sched_in(void)
>> +{
>> +	struct task_struct *task = current;
>> +	struct intel_rdt *ir;
>> +	unsigned int clos;
>> +
>> +	/*
>> +	 * This needs to be fixed
>> +	 * to cache the whole PQR instead of just CLOSid.
>> +	 * PQR has closid in high 32 bits and CQM-RMID in low 10 bits.
>> +	 * Should not write a 0 to the low 10 bits of PQR
>> +	 * and corrupt RMID.
>
> And why is this not fixed __BEFORE__ this patch? You can do the
> changes to struct intel_cqm_state in a seperate patch and then do the
> proper implementation from the beginning instead of providing a half
> broken variant which gets replaced in the next patch.

Ok , can fix both items in your comments. Reason I had it seperately is that the 
cache affects both cmt and cache allocation patches.

>
> Thanks,
>
> 	tglx
>
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/