linux-kernel - Re: [RFC PATCH 3/11] x86, mm, pat: Change reserve

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: <1405465801.28702.34.camel@misato.fc.hp.com>
Date:	Tue, 15 Jul 2014 17:10:01 -0600
From:	Toshi Kani <toshi.kani@...com>
To:	Andy Lutomirski <luto@...capital.net>
Cc:	"H. Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Arnd Bergmann <arnd@...db.de>,
	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
	plagnioj@...osoft.com, tomi.valkeinen@...com,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Stefan Bader <stefan.bader@...onical.com>,
	Dave Airlie <airlied@...il.com>, Borislav Petkov <bp@...en8.de>
Subject: Re: [RFC PATCH 3/11] x86, mm, pat: Change reserve_memtype() to
 handle WT type

On Tue, 2014-07-15 at 12:56 -0700, Andy Lutomirski wrote:
> On Tue, Jul 15, 2014 at 12:34 PM, Toshi Kani <toshi.kani@...com> wrote:
> > This patch changes reserve_memtype() to handle the new WT type.
> > When (!pat_enabled && new_type), it continues to set either WB
> > or UC- to *new_type.  When pat_enabled, it can reserve a given
> > non-RAM range for WT.  At this point, it may not reserve a RAM
> > range for WT since reserve_ram_pages_type() uses the page flags
> > limited to three memory types, WB, WC and UC.
> 
> FWIW, last time I looked at this, it seemed like all the fancy
> reserve_ram_pages stuff was unnecessary: shouldn't the RAM type be
> easy to track in the direct map page tables?

Are you referring the direct map page tables as the kernel page
directory tables (pgd/pud/..)?

I think it needs to be able to keep track of the memory type per a
physical memory range, not per a translation, in order to prevent
aliasing of the memory type.

Thanks,
-Toshi

--
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/