linux-kernel - Re: [PATCH V4 1/3] x86: Make page cache mode a real type

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]

Message-ID: <5450C2F3.40400@suse.com>
Date:	Wed, 29 Oct 2014 11:35:31 +0100
From:	Juergen Gross <jgross@...e.com>
To:	Ingo Molnar <mingo@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>
CC:	hpa@...or.com, x86@...nel.org, mingo@...hat.com,
	stefan.bader@...onical.com, linux-kernel@...r.kernel.org,
	xen-devel@...ts.xensource.com, konrad.wilk@...cle.com,
	ville.syrjala@...ux.intel.com, david.vrabel@...rix.com,
	jbeulich@...e.com, toshi.kani@...com
Subject: Re: [PATCH V4 1/3] x86: Make page cache mode a real type

On 10/29/2014 11:28 AM, Ingo Molnar wrote:
>
> * Thomas Gleixner <tglx@...utronix.de> wrote:
>
>> On Mon, 27 Oct 2014, Juergen Gross wrote:
>>> At the moment there are a lot of places that handle setting or getting
>>> the page cache mode by treating the pgprot bits equal to the cache mode.
>>> This is only true because there are a lot of assumptions about the setup
>>> of the PAT MSR. Otherwise the cache type needs to get translated into
>>> pgprot bits and vice versa.
>>>
>>> This patch tries to prepare for that by introducing a separate type
>>> for the cache mode and adding functions to translate between those and
>>> pgprot values.
>>>
>>> To avoid too much performance penalty the translation between cache mode
>>> and pgprot values is done via tables which contain the relevant
>>> information.  Write-back cache mode is hard-wired to be 0, all other
>>> modes are configurable via those tables. For large pages there are
>>> translation functions as the PAT bit is located at different positions
>>> in the ptes of 4k and large pages.
>>
>> I'm fine with the approach itself. Though I wish you had split this
>> patch in several sanely to review pieces.
>>
>>    - Introduce enums, helper functions etc. which basically reflect
>>      the state of today
>>
>>    - Change the usage sites to use the enums and helpers
>>
>>    - Convert the enum/helper implementation to the new scheme
>>
>>    - Split out the printk change
>>
>>    ...
>
> That absolutely has to be done, should any of this introduce
> regressions. The diffstat:
>
>   18 files changed, 344 insertions(+), 212 deletions(-)
>
> is _way_ too large.

Okay, will do.

Juergen

--
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/