Re: [PATCH v3 2/2] efi: efi_mem_reserve(): don't reserve through memblock after mm_init()

From	Matt Fleming <matt@codeblueprint.co.uk>
Newsgroups	linux.kernel
Subject	Re: [PATCH v3 2/2] efi: efi_mem_reserve(): don't reserve through memblock after mm_init()
Date	2017-01-09 14:10 +0100
Message-ID	<sXHS1-4B7-5@gated-at.bofh.it> (permalink)
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On Fri, 06 Jan, at 07:28:40PM, Ard Biesheuvel wrote:
> 
> This is my point exactly. But it appears efi_free_boot_services()
> occurs much later than I thought, and so there is a sizabe time window
> where SLAB is up but reservations can still be made. But we don't
> check whether efi_free_boot_services() has been called.

True. This has only been correct thus far because all code has been
audited, but adding a check to catch future offenders is a good idea.

> Another problem is that we never check that the reservation is
> covered by a BootServicesData region, which are the only ones that
> are guaranteed to be retained up to this point.

The runtime regions are guaranteed to be retained too.

Again, this shouldn't actually be a problem today, but the potential
for breakage here warrants some kind of check and loud warning.

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[PATCH v3 2/2] efi: efi_mem_reserve(): don't reserve through memblock after mm_init() Nicolai Stange <nicstange@gmail.com> - 2017-01-05 14:00 +0100
  Re: [PATCH v3 2/2] efi: efi_mem_reserve(): don't reserve through  memblock after mm_init() Ard Biesheuvel <ard.biesheuvel@linaro.org> - 2017-01-06 09:40 +0100
    Re: [PATCH v3 2/2] efi: efi_mem_reserve(): don't reserve through memblock after mm_init() Nicolai Stange <nicstange@gmail.com> - 2017-01-06 14:10 +0100
      Re: [PATCH v3 2/2] efi: efi_mem_reserve(): don't reserve through  memblock after mm_init() Ard Biesheuvel <ard.biesheuvel@linaro.org> - 2017-01-06 17:50 +0100
        Re: [PATCH v3 2/2] efi: efi_mem_reserve(): don't reserve through memblock after mm_init() Nicolai Stange <nicstange@gmail.com> - 2017-01-06 18:50 +0100
          Re: [PATCH v3 2/2] efi: efi_mem_reserve(): don't reserve through  memblock after mm_init() Ard Biesheuvel <ard.biesheuvel@linaro.org> - 2017-01-06 20:30 +0100
            Re: [PATCH v3 2/2] efi: efi_mem_reserve(): don't reserve through memblock after mm_init() Nicolai Stange <nicstange@gmail.com> - 2017-01-08 01:30 +0100
              Re: [PATCH v3 2/2] efi: efi_mem_reserve(): don't reserve through  memblock after mm_init() Matt Fleming <matt@codeblueprint.co.uk> - 2017-01-09 14:20 +0100
            Re: [PATCH v3 2/2] efi: efi_mem_reserve(): don't reserve through  memblock after mm_init() Matt Fleming <matt@codeblueprint.co.uk> - 2017-01-09 14:10 +0100

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