Re: [PATCH] Map in physical addresses in efi_map_region_fixed

From	Borislav Petkov <bp@alien8.de>
Newsgroups	linux.kernel
Subject	Re: [PATCH] Map in physical addresses in efi_map_region_fixed
Date	2016-08-16 15:40 +0200
Message-ID	<s6ML1-3GS-67@gated-at.bofh.it> (permalink)
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On Tue, Aug 16, 2016 at 01:30:28PM +0100, Matt Fleming wrote:
> That's impossible, because that would mean we loaded the kexec kernel
> over the top of physical pages of EFI services. We still need to be
> able to invoke EFI services from kexec - we just can't change their
> virtual mappings.

Which would mean that whatever comes second - kexec reservation or 1:1
mappings - won't work.

> This is because of the way that the SGI firmware works and that the
> "new" virtual address mappings are usable on SGI+kexec now.

My only issue is that we probably should've aimed for avoiding that...

> No, some Apple platforms will not boot if SetVirtualAddressMap()
> passes 1:1 mappings, and we only enter the firmware via the 1:1
> mappings for EFI mixed mode calls. We're still using the virtual
> runtime mappings in the commit you reference below most of the time.

... but reasons like the above are making us run the kexec kernel with
the exact-same mappings as the boot kernel. Probably not really a big
deal since we have our own pagetable...

-- 
Regards/Gruss,
    Boris.

ECO tip #101: Trim your mails when you reply.
--

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Re: [PATCH] Map in physical addresses in efi_map_region_fixed Matt Fleming <matt@codeblueprint.co.uk> - 2016-08-15 14:50 +0200
  Re: [PATCH] Map in physical addresses in efi_map_region_fixed Borislav Petkov <bp@alien8.de> - 2016-08-15 17:10 +0200
    Re: [PATCH] Map in physical addresses in efi_map_region_fixed Alex Thorlton <athorlton@sgi.com> - 2016-08-15 20:50 +0200
      Re: [PATCH] Map in physical addresses in efi_map_region_fixed "H. Peter Anvin" <hpa@zytor.com> - 2016-08-16 00:00 +0200
        Re: [PATCH] Map in physical addresses in efi_map_region_fixed Borislav Petkov <bp@alien8.de> - 2016-08-16 07:40 +0200
      Re: [PATCH] Map in physical addresses in efi_map_region_fixed Borislav Petkov <bp@alien8.de> - 2016-08-16 08:00 +0200
        Re: [PATCH] Map in physical addresses in efi_map_region_fixed Alex Thorlton <athorlton@sgi.com> - 2016-08-16 17:30 +0200
      Re: [PATCH] Map in physical addresses in efi_map_region_fixed Dave Young <dyoung@redhat.com> - 2016-08-17 09:10 +0200
        Re: [PATCH] Map in physical addresses in efi_map_region_fixed Alex Thorlton <athorlton@sgi.com> - 2016-08-17 18:10 +0200
          Re: [PATCH] Map in physical addresses in efi_map_region_fixed Dave Young <dyoung@redhat.com> - 2016-08-18 08:20 +0200
    Re: [PATCH] Map in physical addresses in efi_map_region_fixed Matt Fleming <matt@codeblueprint.co.uk> - 2016-08-16 14:40 +0200
      Re: [PATCH] Map in physical addresses in efi_map_region_fixed Borislav Petkov <bp@alien8.de> - 2016-08-16 15:40 +0200

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