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Date: Fri, 22 Jan 2016 01:03:32 +0530
From: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
To: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Ingo Molnar <mingo@kernel.org>, Thomas Gleixner <tglx@linutronix.de>,
        "H . Peter Anvin" <hpa@zytor.com>, linux-kernel@vger.kernel.org,
        linux-efi@vger.kernel.org,
        Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>,
        Dave Young <dyoung@redhat.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Borislav Petkov <bp@alien8.de>
Subject: Re: [PATCH] x86/efi: Setup separate EFI page tables in kexec paths
Message-ID: <20160121193332.GA17206@linux.vnet.ibm.com>
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* Matt Fleming <matt@codeblueprint.co.uk> [2016-01-21 14:11:59]:

> The switch to using a new dedicated page table for EFI runtime calls
> in commit commit 67a9108ed431 ("x86/efi: Build our own page table
> structures") failed to take into account changes required for the
> kexec code paths, which are unfortunately duplicated in the EFI code.
> 
> Call the allocation and setup functions in kexec_enter_virtual_mode()
> just like we do for __efi_enter_virtual_mode() to avoid hitting
> NULL-pointer dereferences when making EFI runtime calls.
> 
> At the very least, the call to efi_setup_page_tables() should have
> existed for kexec before commit 67a9108ed431. Things just magically
> worked because we were actually using the kernel's page tables that
> contained the required mappings.
> 
> Reported-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
> Cc: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
> Cc: Dave Young <dyoung@redhat.com>
> Cc: Ingo Molnar <mingo@kernel.org>
> Cc: Linus Torvalds <torvalds@linux-foundation.org>
> Cc: Borislav Petkov <bp@alien8.de>
> Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>

Applied this patch on top of tip/x86/efi and was able to build and boot
the kernel.

-- 
Thanks and Regards
Srikar Dronamraju