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

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Date:	Thu, 12 Nov 2015 19:47:37 +0100
From:	Borislav Petkov <bp@...en8.de>
To:	Matt Fleming <matt@...eblueprint.co.uk>
Cc:	Ingo Molnar <mingo@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	"H . Peter Anvin" <hpa@...or.com>, Toshi Kani <toshi.kani@...com>,
	linux-kernel@...r.kernel.org, linux-efi@...r.kernel.org,
	Sai Praneeth Prakhya <sai.praneeth.prakhya@...el.com>,
	Dave Hansen <dave.hansen@...el.com>
Subject: Re: [PATCH 1/6] x86/mm/pageattr: Ensure cpa->pfn only contains page
 frame numbers

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@...en8.de>
> Cc: Sai Praneeth Prakhya <sai.praneeth.prakhya@...el.com>
> Cc: Dave Hansen <dave.hansen@...el.com>
> Signed-off-by: Matt Fleming <matt@...eblueprint.co.uk>
> ---
>  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@...e.de>

-- 
Regards/Gruss,
    Boris.

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