linux-kernel - Re: [PATCH 4/4] x86, efi: Map runtime services 1:1

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Message-ID: <20130610125530.GA11673@pd.tnic>
Date:	Mon, 10 Jun 2013 14:55:30 +0200
From:	Borislav Petkov <bp@...en8.de>
To:	Matt Fleming <matt@...sole-pimps.org>
Cc:	"H. Peter Anvin" <hpa@...or.com>,
	Linux EFI <linux-efi@...r.kernel.org>,
	Matthew Garrett <mjg59@...f.ucam.org>,
	Jiri Kosina <jkosina@...e.cz>, X86-ML <x86@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>, Borislav Petkov <bp@...e.de>
Subject: Re: [PATCH 4/4] x86, efi: Map runtime services 1:1

On Thu, Jun 06, 2013 at 12:38:10PM -0700, H. Peter Anvin wrote:
> On 06/06/2013 12:36 PM, Borislav Petkov wrote:
> > On Thu, Jun 06, 2013 at 12:28:20PM -0700, H. Peter Anvin wrote:
> >> Or we could materialize mappings for this specific PGD. However,
> >> adding a read of %cr3 in __do_page_fault sounds expensive.
> > 
> > Yes, I think we want to make sure all mappings are there when we do an
> > EFI runtime call so that we never #PF while it executes.
> > 
> > Matt mentioned on IRC that the it could be that his EFI runtime is
> > referencing EFI_RESERVED area which we don't map. However, we need to
> > confirm/disprove that first, as it is currently only a hunch.

FWIW,

booting the patchset on my Dell looks good here. Booting at least, I
don't know about other stuff. If you have an EFI test suite or want me
to try stuff out, let me know. efibootmgr output looks sane too.

Btw, I've added a printk to the code so that we know that we've managed
switching to the 1:1 thing:

[    0.073119] efi: Using 1:1 map.

Thanks.

-- 
Regards/Gruss,
    Boris.

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