linux-kernel - Re: [PATCH v7 08/36] x86/mm: Add support to enable SME in early boot processing

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Date:   Tue, 20 Jun 2017 09:38:45 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Tom Lendacky <thomas.lendacky@....com>
Cc:     linux-arch@...r.kernel.org, linux-efi@...r.kernel.org,
        kvm@...r.kernel.org, linux-doc@...r.kernel.org, x86@...nel.org,
        kexec@...ts.infradead.org, linux-kernel@...r.kernel.org,
        kasan-dev@...glegroups.com, xen-devel@...ts.xen.org,
        linux-mm@...ck.org, iommu@...ts.linux-foundation.org,
        Brijesh Singh <brijesh.singh@....com>,
        Toshimitsu Kani <toshi.kani@....com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Matt Fleming <matt@...eblueprint.co.uk>,
        Alexander Potapenko <glider@...gle.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Larry Woodman <lwoodman@...hat.com>,
        Jonathan Corbet <corbet@....net>,
        Joerg Roedel <joro@...tes.org>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Ingo Molnar <mingo@...hat.com>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Dave Young <dyoung@...hat.com>, Rik van Riel <riel@...hat.com>,
        Arnd Bergmann <arnd@...db.de>,
        Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
        Andy Lutomirski <luto@...nel.org>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Juergen Gross <jgross@...e.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Paolo Bonzini <pbonzini@...hat.com>
Subject: Re: [PATCH v7 08/36] x86/mm: Add support to enable SME in early boot
 processing

On Fri, Jun 16, 2017 at 01:51:15PM -0500, Tom Lendacky wrote:
> Add support to the early boot code to use Secure Memory Encryption (SME).
> Since the kernel has been loaded into memory in a decrypted state, encrypt
> the kernel in place and update the early pagetables with the memory
> encryption mask so that new pagetable entries will use memory encryption.
> 
> The routines to set the encryption mask and perform the encryption are
> stub routines for now with functionality to be added in a later patch.
> 
> Because of the need to have the routines available to head_64.S, the
> mem_encrypt.c is always built and #ifdefs in mem_encrypt.c will provide
> functionality or stub routines depending on CONFIG_AMD_MEM_ENCRYPT.
> 
> Signed-off-by: Tom Lendacky <thomas.lendacky@....com>
> ---
>  arch/x86/include/asm/mem_encrypt.h |    8 +++++++
>  arch/x86/kernel/head64.c           |   33 +++++++++++++++++++++---------
>  arch/x86/kernel/head_64.S          |   39 ++++++++++++++++++++++++++++++++++--
>  arch/x86/mm/Makefile               |    4 +---
>  arch/x86/mm/mem_encrypt.c          |   24 ++++++++++++++++++++++
>  5 files changed, 93 insertions(+), 15 deletions(-)

...

> diff --git a/arch/x86/mm/mem_encrypt.c b/arch/x86/mm/mem_encrypt.c
> index b99d469..9a78277 100644
> --- a/arch/x86/mm/mem_encrypt.c
> +++ b/arch/x86/mm/mem_encrypt.c
> @@ -11,6 +11,9 @@
>   */
>  
>  #include <linux/linkage.h>
> +#include <linux/init.h>
> +
> +#ifdef CONFIG_AMD_MEM_ENCRYPT
>  
>  /*
>   * Since SME related variables are set early in the boot process they must
> @@ -19,3 +22,24 @@
>   */
>  unsigned long sme_me_mask __section(.data) = 0;
>  EXPORT_SYMBOL_GPL(sme_me_mask);
> +
> +void __init sme_encrypt_kernel(void)
> +{
> +}

Just the minor:

void __init sme_encrypt_kernel(void) { }

in case you have to respin.

Reviewed-by: Borislav Petkov <bp@...e.de>

-- 
Regards/Gruss,
    Boris.

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