linux-kernel - Re: [PATCH v7 33/36] x86/mm: Use proper encryption attributes with /dev/mem

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Date:   Fri, 23 Jun 2017 11:32:36 +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 33/36] x86/mm: Use proper encryption attributes with
 /dev/mem

On Fri, Jun 16, 2017 at 01:56:07PM -0500, Tom Lendacky wrote:
> When accessing memory using /dev/mem (or /dev/kmem) use the proper
> encryption attributes when mapping the memory.
> 
> To insure the proper attributes are applied when reading or writing
> /dev/mem, update the xlate_dev_mem_ptr() function to use memremap()
> which will essentially perform the same steps of applying __va for
> RAM or using ioremap() for if not RAM.
> 
> To insure the proper attributes are applied when mmapping /dev/mem,
> update the phys_mem_access_prot() to call phys_mem_access_encrypted(),
> a new function which will check if the memory should be mapped encrypted
> or not. If it is not to be mapped encrypted then the VMA protection
> value is updated to remove the encryption bit.
> 
> Signed-off-by: Tom Lendacky <thomas.lendacky@....com>
> ---
>  arch/x86/include/asm/io.h |    3 +++
>  arch/x86/mm/ioremap.c     |   18 +++++++++---------
>  arch/x86/mm/pat.c         |    3 +++
>  3 files changed, 15 insertions(+), 9 deletions(-)

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

-- 
Regards/Gruss,
    Boris.

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