linux-kernel - Re: [PATCH -v2 0/4] EFI 1:1 mapping

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Date:	Fri, 21 Jun 2013 07:34:43 +0100
From:	Matt Fleming <matt@...sole-pimps.org>
To:	Borislav Petkov <bp@...en8.de>
Cc:	Matthew Garrett <mjg59@...f.ucam.org>,
	Ingo Molnar <mingo@...nel.org>,
	Linux EFI <linux-efi@...r.kernel.org>, X86 ML <x86@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Borislav Petkov <bp@...e.de>, "H. Peter Anvin" <hpa@...or.com>
Subject: Re: [PATCH -v2 0/4] EFI 1:1 mapping

On Wed, 19 Jun, at 06:59:02PM, Borislav Petkov wrote:
> On Wed, Jun 19, 2013 at 05:48:22PM +0100, Matthew Garrett wrote:
> > > Ok, so it sounds like we want to *always* create both mappings but,
> > > depending on what we want, to shove down SetVirtualAddressMap a
> > > different set. And the 1:1 map will be the optional one which we give
> > > SetVirtualAddressMap only when user wants it, i.e. when booting with
> > > "efi=1:1_map".
> > 
> > Yup, I think that sounds ideal.
> 
> Crap, I got completely sidetracked. The 1:1 mappings go in a different
> pagetable (real_mode_header->trampoline_pgd) than the kernel one
> (i.e. init_mm.pgd). However, the ->trampoline_pgd has all mappings
> anyway, which means that if we want to do EFI runtime calls with the
> high mappings but *also* have the 1:1 mappings established, we should
> *always* switch to that pagetable when doing those calls.
> 
> hpa, MattF, agreed?

Yep.

-- 
Matt Fleming, Intel Open Source Technology Center
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