linux-kernel - Re: [REGRESSION] EFI mixed mode patch triggers boot failure

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Date:   Mon, 24 Oct 2016 12:54:11 -0700
From:   Laura Abbott <labbott@...hat.com>
To:     Matt Fleming <matt@...eblueprint.co.uk>
Cc:     "x86@...nel.org" <x86@...nel.org>, linux-kernel@...r.kernel.org,
        linux-efi@...r.kernel.org, Justin Forbes <jforbes@...hat.com>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>
Subject: Re: [REGRESSION] EFI mixed mode patch triggers boot failure

On 10/20/2016 05:03 AM, Matt Fleming wrote:
> On Wed, 19 Oct, at 02:13:00PM, Laura Abbott wrote:
>> On 10/19/2016 01:04 PM, Laura Abbott wrote:
>>> Hi,
>>>
>>> Fedora received a bug report https://bugzilla.redhat.com/show_bug.cgi?id=1384238
>>> of a bootup failure with stable 4.7.6. efi=noruntime fixed the bootup problem.
>>> 1297667083d5442aafe3e337b9413bf02b114edb was linked as the cause
>>> of the problem.
>>>
>>>
>>> x86/efi: Only map RAM into EFI page tables if in mixed-mode
>>>
>>> Waiman reported that booting with CONFIG_EFI_MIXED enabled on his
>>> multi-terabyte HP machine results in boot crashes, because the EFI
>>> region mapping functions loop forever while trying to map those
>>> regions describing RAM.
>>>
>>> While this patch doesn't fix the underlying hang, there's really no
>>> reason to map EFI_CONVENTIONAL_MEMORY regions into the EFI page tables
>>> when mixed-mode is not in use at runtime.
>>>
>>> Reported-by: Waiman Long <waiman.long@....com>
>>> Cc: Ard Biesheuvel <ard.biesheuvel@...aro.org>
>>> Cc: Borislav Petkov <bp@...en8.de>
>>> Cc: Linus Torvalds <torvalds@...ux-foundation.org>
>>> CC: Theodore Ts'o <tytso@....edu>
>>> Cc: Arnd Bergmann <arnd@...db.de>
>>> Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
>>> Cc: Scott J Norton <scott.norton@....com>
>>> Cc: Douglas Hatch <doug.hatch@....com>
>>> Cc: <stable@...r.kernel.org> # v4.6+
>>> Signed-off-by: Matt Fleming <matt@...eblueprint.co.uk>
>>>
>>> I made a request in the bugzilla for the reporter to
>>> give a bootlog with efi=debug which I'm still waiting on.
>>>
>>> Any ideas?
>>>
>>> Thanks,
>>> Laura
>>
>> dmesg with efi=debug from the reporter is attached
>
>> [    0.000000] DMI: Hewlett-Packard Compaq CQ58 Notebook PC/188B, BIOS F.36 06/07/2013
>
> Hmm.. this is a fairly old machine, what kernel versions has the
> reporter successfully run on it? The code that was nop'd out in the
> above commit for the native case only came into existence in v4.6.
>
> The fact that booting with efi=old_map does *not* seem to result in a
> booting kernel is very suspicious. Could you ask them to double-check?
>
> Maybe try this patch too on v4.7.6.

Was out for a few days, reporter says the below patch does not work.
There was some confusion with secure boot so I've asked them to re-test
with efi=old_map and secure boot off.

Thanks,
Laura

>
> ---
>
> diff --git a/arch/x86/platform/efi/efi_64.c b/arch/x86/platform/efi/efi_64.c
> index 964c7022d31d..b07183c6b470 100644
> --- a/arch/x86/platform/efi/efi_64.c
> +++ b/arch/x86/platform/efi/efi_64.c
> @@ -244,9 +244,12 @@ int __init efi_setup_page_tables(unsigned long pa_memmap, unsigned num_pages)
>  	 * text and allocate a new stack because we can't rely on the
>  	 * stack pointer being < 4GB.
>  	 */
> -	if (!IS_ENABLED(CONFIG_EFI_MIXED) || efi_is_native())
> +	if (!IS_ENABLED(CONFIG_EFI_MIXED))
>  		return 0;
>
> +	if (efi_is_native())
> +		goto map_text;
> +
>  	/*
>  	 * Map all of RAM so that we can access arguments in the 1:1
>  	 * mapping when making EFI runtime calls.
> @@ -273,6 +276,7 @@ int __init efi_setup_page_tables(unsigned long pa_memmap, unsigned num_pages)
>  	efi_scratch.phys_stack = virt_to_phys(page_address(page));
>  	efi_scratch.phys_stack += PAGE_SIZE; /* stack grows down */
>
> +map_text:
>  	npages = (_etext - _text) >> PAGE_SHIFT;
>  	text = __pa(_text);
>  	pfn = text >> PAGE_SHIFT;
>