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Date:   Wed, 27 Jul 2022 09:39:19 +0700
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Subject: Re: [PATCH 2/2] iommu/amd: Add support for AVIC when SNP is enabled
Content-Language: en-US
To:     Jerry Snitselaar <jsnitsel@redhat.com>
Cc:     linux-kernel@vger.kernel.org, iommu@lists.linux.dev,
        joro@8bytes.org, will@kernel.org, vasant.hegde@amd.com,
        jon.grimm@amd.com
References: <20220726134348.6438-1-suravee.suthikulpanit@amd.com>
 <20220726134348.6438-3-suravee.suthikulpanit@amd.com>
 <20220726153227.caqf6hagmwu727ls@cantor>
From:   Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
In-Reply-To: <20220726153227.caqf6hagmwu727ls@cantor>
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On 7/26/22 10:32 PM, Jerry Snitselaar wrote:
> On Tue, Jul 26, 2022 at 08:43:48AM -0500, Suravee Suthikulpanit wrote:
>> In order to support AVIC on SNP-enabled system, The IOMMU driver needs to
>> check EFR2[SNPAVICSup] and enables the support by setting SNPAVICEn bit
>> in the IOMMU control register (MMIO offset 18h).
>>
>> For detail, please see section "SEV-SNP Guest Virtual APIC Support" of the
>> AMD I/O Virtualization Technology (IOMMU) Specification.
>> (https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.amd.com%2Fsystem%2Ffiles%2FTechDocs%2F48882_IOMMU.pdf&amp;data=05%7C01%7Csuravee.suthikulpanit%40amd.com%7C844cc78ad4674484b1f208da6f1c0ee1%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637944463702725122%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&amp;sdata=U%2Fe%2FxqqQ14UmlF5ThaB55Col4mbNzuqNj8IqEyxmsxo%3D&amp;reserved=0)
>>
>> Signed-off-by: Suravee Suthikulpanit<suravee.suthikulpanit@amd.com>
> Is this a typo in the 3.06 spec for SNPAVIC_EN?
> 
> "001b-111b = Reserved."
> 
> Or I guess maybe there is a newer revision that isn't available yet
> that describes 001b?

That's correct. The newer version should be coming out soon.

> Reviewed-by: Jerry Snitselaar<jsnitsel@redhat.com>

Thank you,
Suravee