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iommu/amd: Do not identity map v2 capable device when snp is enabled

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Flow:
  - Booted system with SNP enabled, memory encryption off and
    IOMMU DMA translation mode
  - AMD driver detects v2 capable device and amd_iommu_def_domain_type()
    returns identity mode
  - amd_iommu_domain_alloc() returns NULL an SNP is enabled
  - System will fail to register device

On SNP enabled system, passthrough mode is not supported. IOMMU default
domain is set to translation mode. We need to return zero from
amd_iommu_def_domain_type() so that it allocates translation domain.

Fixes: fb2accadaa ("iommu/amd: Introduce function to check and enable SNP")
CC: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Signed-off-by: Vasant Hegde <vasant.hegde@amd.com>
Link: https://lore.kernel.org/r/20230207091752.7656-1-vasant.hegde@amd.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
This commit is contained in:
Vasant Hegde 2023-02-07 09:17:52 +00:00 committed by Joerg Roedel
parent b6b26d86c6
commit 18792e99ea
1 changed files with 9 additions and 4 deletions
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13
drivers/iommu/amd/iommu.c
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@ -2403,12 +2403,17 @@ static int amd_iommu_def_domain_type(struct device *dev)
return 0;
/*
* Do not identity map IOMMUv2 capable devices when memory encryption is
* active, because some of those devices (AMD GPUs) don't have the
* encryption bit in their DMA-mask and require remapping.
* Do not identity map IOMMUv2 capable devices when:
* - memory encryption is active, because some of those devices
* (AMD GPUs) don't have the encryption bit in their DMA-mask
* and require remapping.
* - SNP is enabled, because it prohibits DTE[Mode]=0.
*/
if (!cc_platform_has(CC_ATTR_MEM_ENCRYPT) && dev_data->iommu_v2)
if (dev_data->iommu_v2 &&
!cc_platform_has(CC_ATTR_MEM_ENCRYPT) &&
!amd_iommu_snp_en) {
return IOMMU_DOMAIN_IDENTITY;
}
return 0;
}