Re: [PATCH 1/6] x86/mm/pageattr: Ensure cpa->pfn only contains page frame numbers

From: Borislav Petkov
Date: Thu Nov 12 2015 - 13:47:45 EST

On Thu, Nov 12, 2015 at 03:40:18PM +0000, Matt Fleming wrote:
> The x86 pageattr code is confused about the data that is stored
> cpa->pfn, sometimes it's treated as a page fram number and sometimes
> it's treated as an unshifted physical address.
> The result of this is that the mapping functions do not map the
> intended physical address.
> This isn't a problem in practice because most of the addresses we're
> mapping in the EFI code paths are already mapped in 'trampoline_pgd'
> and so the pageattr mappings functions don't actually do anything in
> this case. But when we move to using a separate page table for the EFI
> runtime this will be an issue.
> Cc: Borislav Petkov <bp@xxxxxxxxx>
> Cc: Sai Praneeth Prakhya <sai.praneeth.prakhya@xxxxxxxxx>
> Cc: Dave Hansen <dave.hansen@xxxxxxxxx>
> Signed-off-by: Matt Fleming <matt@xxxxxxxxxxxxxxxxxxx>
> ---
> arch/x86/mm/pageattr.c | 12 ++++++------
> arch/x86/platform/efi/efi_64.c | 33 ++++++++++++++++++++++-----------
> 2 files changed, 28 insertions(+), 17 deletions(-)

Reviewed-by: Borislav Petkov <bp@xxxxxxx>


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