linux-kernel - Re: [PATCH v3 7/7] iommu/amd: Do not support IOMMUv2 APIs when SNP is enabled

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Date:   Thu, 23 Jun 2022 10:23:57 +0200
From:   Joerg Roedel <joro@...tes.org>
To:     Suravee Suthikulpanit <suravee.suthikulpanit@....com>
Cc:     linux-kernel@...r.kernel.org, iommu@...ts.linux-foundation.org,
        robin.murphy@....com, ashish.kalra@....com, vasant.hegde@....com,
        thomas.lendacky@....com
Subject: Re: [PATCH v3 7/7] iommu/amd: Do not support IOMMUv2 APIs when SNP
 is enabled

On Wed, Jun 22, 2022 at 12:11:31PM -0500, Suravee Suthikulpanit wrote:
>  bool amd_iommu_v2_supported(void)
>  {
> -	return amd_iommu_v2_present;
> +	/*
> +	 * Since DTE[Mode]=0 is prohibited on SNP-enabled system
> +	 * (i.e. EFR[SNPSup]=1), IOMMUv2 page table cannot be used without
> +	 * setting up IOMMUv1 page table.
> +	 */
> +	return amd_iommu_v2_present && !amd_iommu_snp_en;

IOMMU_v2 APIs could actually be supported with GIOV and IOMMUv2
page-tables in-use, no?

Regards,

	Joerg