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Re: efi_enabled(EFI_PARAVIRT) use

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On Fri, 29 Apr, at 10:25:02AM, Borislav Petkov wrote:
> On Fri, Apr 29, 2016 at 08:39:36AM +0200, Ingo Molnar wrote:
> > With considerable pain we just got rid of paravirt_enabled() in the
> > x86 tree, and Xen is now reintroducing it in the EFI code.
> 
> I think Matt is working towards removing EFI_PARAVIRT but he'll comment
> himself when he wakes up... :)

Yeah, I haven't actually got around to dropping EFI_PARAVIRT yet but
since it's basically used to skip certain initialisation operations on
boot I figured we could just provide empty stub functions as part of
struct efi (probably).

The concerns Ingo voiced about EFI_PARAVIRT being a catch-all flag are
very true.

Incidentally kexec and arm64 would need a similar stub functions if we
move more EFI runtime setup code to drivers/firmware/efi, which is my
long-term plan, since neither can call SetVirtualAddressMap().

On x86, I think EFI_PARAVIRT is code for,

  1. Has no EFI memory map
  2. Runtime regions do not need to be mapped
  3. Cannot call SetVirtualAddressMap()
  4. /sys/firmware/efi/fw_vendor is invisible

1. and 2. should be covered by never setting EFI_MEMMAP and
EFI_RUNTIME_SERVICES in efi.flags. We have no bits for 3. and 4. yet.

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Thread

linux-next: manual merge of the xen-tip tree with the tip tree Stephen Rothwell <sfr@canb.auug.org.au> - 2016-04-29 06:30 +0200
  Re: efi_enabled(EFI_PARAVIRT) use Ingo Molnar <mingo@kernel.org> - 2016-04-29 08:40 +0200
    Re: efi_enabled(EFI_PARAVIRT) use Borislav Petkov <bp@alien8.de> - 2016-04-29 10:30 +0200
      Re: efi_enabled(EFI_PARAVIRT) use Matt Fleming <matt@codeblueprint.co.uk> - 2016-04-29 11:30 +0200
    Re: efi_enabled(EFI_PARAVIRT) use Stefano Stabellini <sstabellini@kernel.org> - 2016-04-29 12:40 +0200
      Re: efi_enabled(EFI_PARAVIRT) use Ingo Molnar <mingo@kernel.org> - 2016-04-29 12:50 +0200
      Re: efi_enabled(EFI_PARAVIRT) use Matt Fleming <matt@codeblueprint.co.uk> - 2016-04-29 16:40 +0200
        Re: efi_enabled(EFI_PARAVIRT) use Ard Biesheuvel <ard.biesheuvel@linaro.org> - 2016-04-29 17:00 +0200
          Re: efi_enabled(EFI_PARAVIRT) use Shannon Zhao <shannon.zhao@linaro.org> - 2016-04-30 16:20 +0200
            Re: efi_enabled(EFI_PARAVIRT) use Matt Fleming <matt@codeblueprint.co.uk> - 2016-04-30 22:50 +0200
              Re: efi_enabled(EFI_PARAVIRT) use Shannon Zhao <shannon.zhao@linaro.org> - 2016-05-01 05:30 +0200
                Re: efi_enabled(EFI_PARAVIRT) use Matt Fleming <matt@codeblueprint.co.uk> - 2016-05-01 15:30 +0200
                Re: efi_enabled(EFI_PARAVIRT) use Shannon Zhao <shannon.zhao@linaro.org> - 2016-05-01 16:40 +0200
                Re: efi_enabled(EFI_PARAVIRT) use Matt Fleming <matt@codeblueprint.co.uk> - 2016-05-02 12:50 +0200
                Re: [Xen-devel] efi_enabled(EFI_PARAVIRT) use Shannon Zhao <zhaoshenglong@huawei.com> - 2016-05-03 03:50 +0200
                Re: [Xen-devel] efi_enabled(EFI_PARAVIRT) use Matt Fleming <matt@codeblueprint.co.uk> - 2016-05-04 13:40 +0200
            Re: [Xen-devel] efi_enabled(EFI_PARAVIRT) use Shannon Zhao <zhaoshenglong@huawei.com> - 2016-05-03 11:20 +0200
        Re: efi_enabled(EFI_PARAVIRT) use Stefano Stabellini <sstabellini@kernel.org> - 2016-04-29 17:00 +0200
          Re: efi_enabled(EFI_PARAVIRT) use Stefano Stabellini <sstabellini@kernel.org> - 2016-04-29 17:40 +0200
            Re: efi_enabled(EFI_PARAVIRT) use Shannon Zhao <shannon.zhao@linaro.org> - 2016-04-30 16:10 +0200

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