linux-kernel - Re: [PATCH v7 27/36] iommu/amd: Allow the AMD IOMMU to work with memory encryption

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Date:   Thu, 22 Jun 2017 11:48:46 -0500
From:   Tom Lendacky <thomas.lendacky@....com>
To:     Borislav Petkov <bp@...en8.de>
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 27/36] iommu/amd: Allow the AMD IOMMU to work with
 memory encryption

On 6/22/2017 5:56 AM, Borislav Petkov wrote:
> On Fri, Jun 16, 2017 at 01:54:59PM -0500, Tom Lendacky wrote:
>> The IOMMU is programmed with physical addresses for the various tables
>> and buffers that are used to communicate between the device and the
>> driver. When the driver allocates this memory it is encrypted. In order
>> for the IOMMU to access the memory as encrypted the encryption mask needs
>> to be included in these physical addresses during configuration.
>>
>> The PTE entries created by the IOMMU should also include the encryption
>> mask so that when the device behind the IOMMU performs a DMA, the DMA
>> will be performed to encrypted memory.
>>
>> Signed-off-by: Tom Lendacky <thomas.lendacky@....com>
>> ---
>>   drivers/iommu/amd_iommu.c       |   30 ++++++++++++++++--------------
>>   drivers/iommu/amd_iommu_init.c  |   34 ++++++++++++++++++++++++++++------
>>   drivers/iommu/amd_iommu_proto.h |   10 ++++++++++
>>   drivers/iommu/amd_iommu_types.h |    2 +-
>>   4 files changed, 55 insertions(+), 21 deletions(-)
> 
> Reviewed-by: Borislav Petkov <bp@...e.de>
> 
> Btw, I'm assuming the virt_to_phys() difference on SME systems is only
> needed in a handful of places. Otherwise, I'd suggest changing the
> virt_to_phys() function/macro directly. But I guess most of the places
> need the real physical address without the enc bit.

Correct.

Thanks,
Tom

>