linux-kernel - Re: [PATCH 1/3] iommu/amd: Add logic to decode AMD IOMMU event flag

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 for Android: free password hash cracker in your pocket

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

Message-ID: <20130402193240.GF17675@pd.tnic>
Date:	Tue, 2 Apr 2013 21:32:40 +0200
From:	Borislav Petkov <bp@...en8.de>
To:	Joerg Roedel <joro@...tes.org>
Cc:	suravee.suthikulpanit@....com, iommu@...ts.linux-foundation.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/3] iommu/amd: Add logic to decode AMD IOMMU event flag

On Tue, Apr 02, 2013 at 06:33:18PM +0200, Joerg Roedel wrote:
> I can't find out in the driver whether the fix works or not. It will
> be noticed later when the x86 code tries to setup the timers and finds
> out that they don't work, which causes a kernel panic.
>
> Okay, in theory I could implement a feedback loop between timer-setup
> and intremap code and try fixups until it works. But that seems not to
> be worth it to work around a buggy BIOS.

Yeah, same here. It's not like we really need intremap to work - we're
only trying to fix the annoying error message currently. :-)

> What I actually thought about was providing an IVRS-override on the
> kernel command line. So that you can specify the IOAPIC_ID->DEVID
> mapping there and make it work this way. What do you think?

I guess that is workable. I can imagine people wanting this if they want
to do the intremap thing on such b0rked BIOSen. So how do I specify this
IOAPIC_ID->DEVID mapping on the cmdline exactly?

> > And yes, I'm very sceptical about having a WARN_ON and it starts
> > screaming on machines all over the place. Good luck explaining to
> > people that you actually wanted to prod BIOS vendors to fix their
> > monkey-on-crack code but they weren't listening in the first place.
> 
> Yeah, that's my fear too. So we leave it better as it is...

Hohumm.

-- 
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/