linux-kernel - Re: [PATCH] X86: MM: Add PAT Type write-through in combination with mtrr

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: <20131028114541.GI4314@pd.tnic>
Date:	Mon, 28 Oct 2013 12:45:41 +0100
From:	Borislav Petkov <bp@...en8.de>
To:	Andreas Werner <wernerandy@....de>
Cc:	Ingo Molnar <mingo@...nel.org>, tglx@...utronix.de,
	mingo@...hat.com, hpa@...or.com, x86@...nel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] X86: MM: Add PAT Type write-through in combination with
 mtrr

Drop Dave's stale mail address.

On Mon, Oct 28, 2013 at 12:25:05PM +0100, Andreas Werner wrote:
> > but you end up doing
> > 
> >   PAT=Write-Back + MTRR=Write-Through = Effective Memory of Write-Back
> >
> No the effective memory type is WT, check out the Intel document with the
> table of Effective memory type combinations.

You need to read what I'm saying more carefully.

> Yes but, there is no way in the kernel to mark a memory WT,

That doesn't mean you can return _PAGE_CACHE_WB for MTRR_TYPE_WRTHROUGH.
The correct thing to do, IMHO, would be to set the PWT bit in the PTEs
of those pages comprising your buffer.

-- 
Regards/Gruss,
    Boris.

Sent from a fat crate under my desk. Formatting is fine.
--
--
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/