Date: Thu, 27 Jul 2017 15:31:25 +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 06/17] x86/mm: Use encrypted access of boot
 related data with SEV
Message-ID: <20170727133125.GB28553@nazgul.tnic>
References: <20170724190757.11278-1-brijesh.singh@amd.com>
 <20170724190757.11278-7-brijesh.singh@amd.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
Content-Transfer-Encoding: 8bit
In-Reply-To: <20170724190757.11278-7-brijesh.singh@amd.com>
User-Agent: Mutt/1.6.0 (2016-04-01)
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 2844
Lines: 93

On Mon, Jul 24, 2017 at 02:07:46PM -0500, Brijesh Singh wrote:
> From: Tom Lendacky <thomas.lendacky@amd.com>
> 
> When Secure Encrypted Virtualization (SEV) is active, boot data (such as
> EFI related data, setup data) is encrypted and needs to be accessed as
> such when mapped. Update the architecture override in early_memremap to
> keep the encryption attribute when mapping this data.
> 
> Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
> Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
> ---
>  arch/x86/mm/ioremap.c | 44 ++++++++++++++++++++++++++++++++------------
>  1 file changed, 32 insertions(+), 12 deletions(-)

...

> @@ -590,10 +598,15 @@ bool arch_memremap_can_ram_remap(resource_size_t phys_addr, unsigned long size,
>  	if (flags & MEMREMAP_DEC)
>  		return false;
>  
> -	if (memremap_is_setup_data(phys_addr, size) ||
> -	    memremap_is_efi_data(phys_addr, size) ||
> -	    memremap_should_map_decrypted(phys_addr, size))
> -		return false;
> +	if (sme_active()) {
> +		if (memremap_is_setup_data(phys_addr, size) ||
> +		    memremap_is_efi_data(phys_addr, size) ||
> +		    memremap_should_map_decrypted(phys_addr, size))
> +			return false;
> +	} else if (sev_active()) {
> +		if (memremap_should_map_decrypted(phys_addr, size))
> +			return false;
> +	}
>  
>  	return true;
>  }

I guess this function's hind part can be simplified to:

        if (sme_active()) {
                if (memremap_is_setup_data(phys_addr, size) ||
                    memremap_is_efi_data(phys_addr, size))
                        return false;
        }

        return ! memremap_should_map_decrypted(phys_addr, size);
}

> @@ -608,15 +621,22 @@ pgprot_t __init early_memremap_pgprot_adjust(resource_size_t phys_addr,
>  					     unsigned long size,
>  					     pgprot_t prot)

And this one in a similar manner...

>  {
> -	if (!sme_active())
> +	if (!sme_active() && !sev_active())
>  		return prot;

... and you don't need that check...

> -	if (early_memremap_is_setup_data(phys_addr, size) ||
> -	    memremap_is_efi_data(phys_addr, size) ||
> -	    memremap_should_map_decrypted(phys_addr, size))
> -		prot = pgprot_decrypted(prot);
> -	else
> -		prot = pgprot_encrypted(prot);
> +	if (sme_active()) {

... if you're going to do it here too.

> +		if (early_memremap_is_setup_data(phys_addr, size) ||
> +		    memremap_is_efi_data(phys_addr, size) ||
> +		    memremap_should_map_decrypted(phys_addr, size))
> +			prot = pgprot_decrypted(prot);
> +		else
> +			prot = pgprot_encrypted(prot);
> +	} else if (sev_active()) {

And here.

> +		if (memremap_should_map_decrypted(phys_addr, size))
> +			prot = pgprot_decrypted(prot);
> +		else
> +			prot = pgprot_encrypted(prot);
> +	}

-- 
Regards/Gruss,
    Boris.

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