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

H. Peter Anvin
2013-06-20T21:27:16Z

On 06/19/2013 09:59 AM, 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?
>

Yes.

-hpa