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x86/efi: Don't unmap EFI boot services code/data regions for EFI_OLD_MEMMAP and EFI_MIXED_MODE 

The following commit:

  d5052a7130a6 ("x86/efi: Unmap EFI boot services code/data regions from efi_pgd")

forgets to take two EFI modes into consideration, namely EFI_OLD_MEMMAP and
EFI_MIXED_MODE:

- EFI_OLD_MEMMAP is a legacy way of mapping EFI regions into swapper_pg_dir
  using ioremap() and init_memory_mapping(). This feature can be enabled by
  passing "efi=old_map" as kernel command line argument. But,
  efi_unmap_pages() unmaps EFI boot services code/data regions *only* from
  efi_pgd and hence cannot be used for unmapping EFI boot services code/data
  regions from swapper_pg_dir.

Introduce a temporary fix to not unmap EFI boot services code/data regions
when EFI_OLD_MEMMAP is enabled while working on a real fix.

- EFI_MIXED_MODE is another feature where a 64-bit kernel runs on a
  64-bit platform crippled by a 32-bit firmware. To support EFI_MIXED_MODE,
  all RAM (i.e. namely EFI regions like EFI_CONVENTIONAL_MEMORY,
  EFI_LOADER_<CODE/DATA>, EFI_BOOT_SERVICES_<CODE/DATA> and
  EFI_RUNTIME_CODE/DATA regions) is mapped into efi_pgd all the time to
  facilitate EFI runtime calls access it's arguments in 1:1 mode.

Hence, don't unmap EFI boot services code/data regions when booted in mixed mode.

Signed-off-by: Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Bhupesh Sharma <bhsharma@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/20181222022234.7573-1-sai.praneeth.prakhya@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Sai Praneeth Prakhya 2018-12-21 18:22:34 -08:00 committed by Ingo Molnar
parent 80424b02d4
commit 1debf0958f
1 changed files with 16 additions and 0 deletions
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16
arch/x86/platform/efi/quirks.c
View File

@ -380,6 +380,22 @@ static void __init efi_unmap_pages(efi_memory_desc_t *md)
u64 pa = md->phys_addr;
u64 va = md->virt_addr;
/*
* To Do: Remove this check after adding functionality to unmap EFI boot
* services code/data regions from direct mapping area because
* "efi=old_map" maps EFI regions in swapper_pg_dir.
*/
if (efi_enabled(EFI_OLD_MEMMAP))
return;
/*
* EFI mixed mode has all RAM mapped to access arguments while making
* EFI runtime calls, hence don't unmap EFI boot services code/data
* regions.
*/
if (!efi_is_native())
return;
if (kernel_unmap_pages_in_pgd(pgd, pa, md->num_pages))
pr_err("Failed to unmap 1:1 mapping for 0x%llx\n", pa);