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

[Borislav Petkov]

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@xxxxxxx>
> ---
>  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@xxxxxxx>

-- 
Regards/Gruss,
    Boris.

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