linux-kernel - Re: [PATCH 1/2] VMware detection support for x86 and x86-64

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: <20080917105238.GF18764@elte.hu>
Date:	Wed, 17 Sep 2008 12:52:38 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Yan Li <elliot.li.tech@...il.com>
Cc:	"H. Peter Anvin" <hpa@...or.com>, linux-kernel@...r.kernel.org,
	joerg.roedel@....com, rjmaomao@...il.com,
	Yinghai Lu <yhlu.kernel@...il.com>,
	Thomas Gleixner <tglx@...utronix.de>, nancydreaming@...il.com
Subject: Re: [PATCH 1/2] VMware detection support for x86 and x86-64


* Yan Li <elliot.li.tech@...il.com> wrote:

> On Mon, Sep 08, 2008 at 05:34:07PM -0700, H. Peter Anvin wrote:
> >> VMware may change the PCI ID at their will so I prefer checking the
> >> DMI since it's easier.
> >>
> >> So if we ditched the official method we run the risk of some false
> >> negatives.  But checking the DMI manufacturer would be good enough.
> >>
> >
> > If we get false negatives that is quite frankly their problem, not ours.  
> >  If nothing else, we should be able to look for a host bridge with the  
> > VMWare vendor ID -- that should arguably be safer than DMI.
> 
> I found that in this situation we can't use PCI info.  My intention to
> do this is to fix the false warning from
> arch/x86/kernel/cpu/mtrr/main.c (around L695). When booting a VMware
> guest we got:
> "WARNING: strange, CPU MTRRs all blank?"
> 
> For VMware guest this warning is false, just as that for a KVM guest.
> 
> This code is from mtrr_trim_uncached_memory(), and used by
> setup_arch(), which is used far before PCI is ready.
> 
> Therefore I think we can only use DMI here. Any idea?

PCI quirks can be used almost arbitrarily early stage, see:
arch/x86/kernel/early-quirks.c.

Adding a VM identification callback to early-quirks.c would be fine. But 
if there's a reliable and specific enough DMI string that's fine as 
well. (but PCI is better, since it's a generally more stable enumeration 
interface)

	Ingo
--
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/