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

Matthew Garrett
2013-06-20T18:17:39Z

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