linux-kernel - Re: [PATCH v5 06/32] x86/mm: Add Secure Memory Encryption (SME) support

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Date:   Thu, 27 Apr 2017 17:46:31 +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, linux-mm@...ck.org,
        iommu@...ts.linux-foundation.org, Rik van Riel <riel@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Toshimitsu Kani <toshi.kani@....com>,
        Arnd Bergmann <arnd@...db.de>,
        Jonathan Corbet <corbet@....net>,
        Matt Fleming <matt@...eblueprint.co.uk>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Joerg Roedel <joro@...tes.org>,
        Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Larry Woodman <lwoodman@...hat.com>,
        Brijesh Singh <brijesh.singh@....com>,
        Ingo Molnar <mingo@...hat.com>,
        Andy Lutomirski <luto@...nel.org>,
        "H. Peter Anvin" <hpa@...or.com>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Alexander Potapenko <glider@...gle.com>,
        Dave Young <dyoung@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Dmitry Vyukov <dvyukov@...gle.com>
Subject: Re: [PATCH v5 06/32] x86/mm: Add Secure Memory Encryption (SME)
 support

On Tue, Apr 18, 2017 at 04:17:27PM -0500, Tom Lendacky wrote:
> Add support for Secure Memory Encryption (SME). This initial support
> provides a Kconfig entry to build the SME support into the kernel and
> defines the memory encryption mask that will be used in subsequent
> patches to mark pages as encrypted.

...

> diff --git a/arch/x86/include/asm/mem_encrypt.h b/arch/x86/include/asm/mem_encrypt.h
> new file mode 100644
> index 0000000..d5c4a2b
> --- /dev/null
> +++ b/arch/x86/include/asm/mem_encrypt.h
> @@ -0,0 +1,42 @@
> +/*
> + * AMD Memory Encryption Support
> + *
> + * Copyright (C) 2016 Advanced Micro Devices, Inc.
> + *
> + * Author: Tom Lendacky <thomas.lendacky@....com>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +

These ifdeffery closing #endif markers look strange:

> +#ifndef __X86_MEM_ENCRYPT_H__
> +#define __X86_MEM_ENCRYPT_H__
> +
> +#ifndef __ASSEMBLY__
> +
> +#ifdef CONFIG_AMD_MEM_ENCRYPT
> +
> +extern unsigned long sme_me_mask;
> +
> +static inline bool sme_active(void)
> +{
> +	return !!sme_me_mask;
> +}
> +
> +#else	/* !CONFIG_AMD_MEM_ENCRYPT */
> +
> +#ifndef sme_me_mask
> +#define sme_me_mask	0UL
> +
> +static inline bool sme_active(void)
> +{
> +	return false;
> +}
> +#endif

this endif is the sme_me_mask closing one and it has sme_active() in it.
Shouldn't it be:

#ifndef sme_me_mask
#define sme_me_mask  0UL
#endif

and have sme_active below it, in the !CONFIG_AMD_MEM_ENCRYPT branch?

The same thing is in include/linux/mem_encrypt.h

-- 
Regards/Gruss,
    Boris.

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