Commit 18792e99 authored by Vasant Hegde's avatar Vasant Hegde Committed by Joerg Roedel
Browse files

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



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: fb2accad ("iommu/amd: Introduce function to check and enable SNP")
CC: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Signed-off-by: default avatarVasant Hegde <vasant.hegde@amd.com>
Link: https://lore.kernel.org/r/20230207091752.7656-1-vasant.hegde@amd.com


Signed-off-by: default avatarJoerg Roedel <jroedel@suse.de>
parent b6b26d86

drivers/iommu/amd/iommu.c

+9 −4
Original line number Diff line number Diff line
@@ -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;

}