linux-kernel - Re: [PATCH] x86, efi: retry ExitBootServices() on failure

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Date:	Tue, 11 Jun 2013 08:22:22 +0100
From:	Matt Fleming <matt@...sole-pimps.org>
To:	linux-efi@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org,
	Matthew Garrett <mjg59@...f.ucam.org>,
	Zach Bobroff <zacharyb@....com>, stable@...r.kernel.org,
	Matt Fleming <matt.fleming@...el.com>
Subject: Re: [PATCH] x86, efi: retry ExitBootServices() on failure

On Tue, 11 Jun, at 07:52:38AM, Matt Fleming wrote:
> From: Zach Bobroff <zacharyb@....com>
> 
> ExitBootServices is absolutely supposed to return a failure if any
> ExitBootServices event handler changes the memory map.  Basically the
> get_map loop should run again if ExitBootServices returns an error the
> first time.  I would say it would be fair that if ExitBootServices gives
> an error the second time then Linux would be fine in returning control
> back to BIOS.
> 
> The second change is the following line:
> 
> again:
>         size += sizeof(*mem_map) * 2;
> 
> Originally you were incrementing it by the size of one memory map entry.
> The issue here is all related to the low_alloc routine you are using.
> In this routine you are making allocations to get the memory map itself.
> Doing this allocation or allocations can affect the memory map by more
> than one record.
> 
> [ mfleming - changelog, code style ]
> Signed-off-by: Zach Bobroff <zacharyb@....com>
> Cc: <stable@...r.kernel.org>
> Signed-off-by: Matt Fleming <matt.fleming@...el.com>
> ---
>  arch/x86/boot/compressed/eboot.c | 20 +++++++++++++++++---
>  1 file changed, 17 insertions(+), 3 deletions(-)

I've queued this patch up for v3.11 in my 'next' branch.

-- 
Matt Fleming, Intel Open Source Technology Center
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