From: Vasant Hegde vasant.hegde@amd.com
[ Upstream commit 18792e99ea2fea27c72eb1ecca1879e5e6be304d ]
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: fb2accadaa94 ("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 Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/iommu/amd/iommu.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-)
diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c index 9dc41c48c29d6..ff4f3d4da3402 100644 --- a/drivers/iommu/amd/iommu.c +++ b/drivers/iommu/amd/iommu.c @@ -2405,12 +2405,17 @@ 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; }