linux-kernel - Re: [PATCH v8 RESEND 27/38] iommu/amd: Allow the AMD IOMMU to work with memory encryption

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Message-ID: <03a9d0f5-1f0e-ca0c-78a4-c3a7242f6935@amd.com>
Date:   Wed, 28 Jun 2017 09:05:44 -0500
From:   Tom Lendacky <thomas.lendacky@....com>
To:     Joerg Roedel <joro@...tes.org>
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>,
        "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>,
        Borislav Petkov <bp@...en8.de>,
        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 v8 RESEND 27/38] iommu/amd: Allow the AMD IOMMU to work
 with memory encryption

On 6/28/2017 4:36 AM, Joerg Roedel wrote:
> Hi Tom,

Hi Joerg,

> 
> On Tue, Jun 27, 2017 at 10:12:30AM -0500, Tom Lendacky wrote:
>> ---
>>   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(-)
> 
> Looks like a straightforward change. Just one nit below.
> 
>> +static bool amd_iommu_supports_sme(void)
>> +{
>> +	if (!sme_active() || (boot_cpu_data.x86 != 0x17))
>> +		return true;
>> +
>> +	/* For Fam17h, a specific level of support is required */
>> +	if (boot_cpu_data.microcode >= 0x08001205)
>> +		return true;
>> +
>> +	if ((boot_cpu_data.microcode >= 0x08001126) &&
>> +	    (boot_cpu_data.microcode <= 0x080011ff))
>> +		return true;
>> +
>> +	pr_notice("AMD-Vi: IOMMU not currently supported when SME is active\n");
>> +
>> +	return false;
>> +}
> 
> The name of the function is misleading. It checks whether the IOMMU can
> be enabled when SME is active. But the name suggests that it checks
> whether the iommu hardware supports SME.
> 
> How about renaming it to amd_iommu_sme_check()?

Can do.

Thanks,
Tom

> 
> With that change the patch is:
> 
> 	Acked-by: Joerg Roedel <jroedel@...e.de>
>