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Date: Thu, 20 Jun 2013 19:17:31 +0100
From: Matthew Garrett <mjg59@srcf.ucam.org>
To: Borislav Petkov <bp@alien8.de>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>,
        Ingo Molnar <mingo@kernel.org>, Linux EFI <linux-efi@vger.kernel.org>,
        Matt Fleming <matt@console-pimps.org>, X86 ML <x86@kernel.org>,
        LKML <linux-kernel@vger.kernel.org>, Borislav Petkov <bp@suse.de>
Subject: Re: [PATCH -v2 0/4] EFI 1:1 mapping
Message-ID: <20130620181731.GA27960@srcf.ucam.org>
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On Thu, Jun 20, 2013 at 08:14:45PM +0200, Borislav Petkov wrote:
> On Thu, Jun 20, 2013 at 07:10:15PM +0100, Matthew Garrett wrote:
> > Because Windows passes high addresses to SetVirtualAddressMap(), and
> > because if you can imagine firmware developers getting it wrong then
> > firmware developers will have got it wrong.
> 
> Can we reversely assume that if we'd used fixed high offsets, as hpa
> suggests, then it'll be fine? IOW, are any high addresses, even fixed
> ones, fine?

Windows actually seems to start at the top of address space and go down 
- this is what I get booting Windows 8 under kvm. It looks like very 
high addresses are fine, and we're currently using "low" high addresses, 
so I suspect we're fine pretty much anywhere in that range.

****** SetVirtualAddressMap
Type: 5
Physical Start: 3E878000
Virtual Start: FFFFFFFFFFBEB000
Number Of Pages: 15
Attributes: 800000000000000F
Type: 6
Physical Start: 3E88D000
Virtual Start: FFFFFFFFFFBD6000
Number Of Pages: 15
Attributes: 800000000000000F
Type: 5
Physical Start: 3FB22000
Virtual Start: FFFFFFFFFFBA6000
Number Of Pages: 30
Attributes: 800000000000000F
Type: 6
Physical Start: 3FB52000
Virtual Start: FFFFFFFFFFB82000
Number Of Pages: 24
Attributes: 800000000000000F
Type: 6
Physical Start: 3FFE0000
Virtual Start: FFFFFFFFFFB62000
Number Of Pages: 20


-- 
Matthew Garrett | mjg59@srcf.ucam.org
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