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Date: Mon, 4 Dec 2017 20:31:07 +0100
From: Borislav Petkov <bp@suse.de>
To: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>, x86@kernel.org,
        Thomas Gleixner <tglx@linutronix.de>, "H. Peter Anvin" <hpa@zytor.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Andy Lutomirski <luto@amacapital.net>,
        Cyrill Gorcunov <gorcunov@openvz.org>, Andi Kleen <ak@linux.intel.com>,
        linux-mm@kvack.org, linux-kernel@vger.kernel.org,
        stable@vger.kernel.org
Subject: Re: [PATCHv3 2/5] x86/boot/compressed/64: Print error if 5-level
 paging is not supported
Message-ID: <20171204193107.ni42cydrxp5utg3n@pd.tnic>
References: <20171204124059.63515-1-kirill.shutemov@linux.intel.com>
 <20171204124059.63515-3-kirill.shutemov@linux.intel.com>
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On Mon, Dec 04, 2017 at 03:40:56PM +0300, Kirill A. Shutemov wrote:
> We cannot proceed booting if the machine doesn't support the paging mode
> kernel was compiled for.
> 
> Getting error the usual way -- via validate_cpu() -- is not going to
> work. We need to enable appropriate paging mode before that, otherwise
> kernel would triple-fault during KASLR setup.
> 
> This code will go away once we get support for boot-time switching
> between paging modes.
> 
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
> Cc: <stable@vger.kernel.org>	[4.14+]
> ---
>  arch/x86/boot/compressed/misc.c       | 16 ++++++++++++++++
>  arch/x86/boot/compressed/pgtable_64.c |  2 +-
>  2 files changed, 17 insertions(+), 1 deletion(-)

Reported-and-tested-by: Borislav Petkov <bp@suse.de>

-- 
Regards/Gruss,
    Boris.

SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)
--