Date: Thu, 27 Jul 2017 16:58:41 +0200
From: Borislav Petkov <bp@suse.de>
To: Brijesh Singh <brijesh.singh@amd.com>
Cc: linux-kernel@vger.kernel.org, x86@kernel.org,
        linux-efi@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
        kvm@vger.kernel.org, Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, "H . Peter Anvin" <hpa@zytor.com>,
        Andy Lutomirski <luto@kernel.org>, Tony Luck <tony.luck@intel.com>,
        Piotr Luc <piotr.luc@intel.com>,
        Tom Lendacky <thomas.lendacky@amd.com>,
        Fenghua Yu <fenghua.yu@intel.com>, Lu Baolu <baolu.lu@linux.intel.com>,
        Reza Arbab <arbab@linux.vnet.ibm.com>,
        David Howells <dhowells@redhat.com>,
        Matt Fleming <matt@codeblueprint.co.uk>,
        "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
        Laura Abbott <labbott@redhat.com>,
        Ard Biesheuvel <ard.biesheuvel@linaro.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Eric Biederman <ebiederm@xmission.com>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>,
        Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
        Jonathan Corbet <corbet@lwn.net>, Dave Airlie <airlied@redhat.com>,
        Kees Cook <keescook@chromium.org>, Paolo Bonzini <pbonzini@redhat.com>,
        Radim =?utf-8?B?S3LEjW3DocWZ?= <rkrcmar@redhat.com>,
        Arnd Bergmann <arnd@arndb.de>, Tejun Heo <tj@kernel.org>,
        Christoph Lameter <cl@linux.com>
Subject: Re: [RFC Part1 PATCH v3 07/17] x86/mm: Include SEV for encryption
 memory attribute changes
Message-ID: <20170727145841.GG28553@nazgul.tnic>
References: <20170724190757.11278-1-brijesh.singh@amd.com>
 <20170724190757.11278-8-brijesh.singh@amd.com>
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On Mon, Jul 24, 2017 at 02:07:47PM -0500, Brijesh Singh wrote:
> From: Tom Lendacky <thomas.lendacky@amd.com>
> 
> The current code checks only for sme_active() when determining whether
> to perform the encryption attribute change.  Include sev_active() in this
> check so that memory attribute changes can occur under SME and SEV.
> 
> Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
> Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
> ---
>  arch/x86/mm/pageattr.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
> index dfb7d65..b726b23 100644
> --- a/arch/x86/mm/pageattr.c
> +++ b/arch/x86/mm/pageattr.c
> @@ -1781,8 +1781,8 @@ static int __set_memory_enc_dec(unsigned long addr, int numpages, bool enc)
>  	unsigned long start;
>  	int ret;
>  
> -	/* Nothing to do if the SME is not active */
> -	if (!sme_active())
> +	/* Nothing to do if SME and SEV are not active */
> +	if (!sme_active() && !sev_active())

This is the second place which does

	if (!SME && !SEV)

I wonder if, instead of sprinking those, we should have a

	if (mem_enc_active())

or so which unifies all those memory encryption logic tests and makes
the code more straightforward for readers who don't have to pay
attention to SME vs SEV ...

Just a thought.

-- 
Regards/Gruss,
    Boris.

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