From: Vasant Hegde <vasant.hegde@xxxxxxx>
[ 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@xxxxxxx>
Signed-off-by: Vasant Hegde <vasant.hegde@xxxxxxx>
Link: https://lore.kernel.org/r/20230207091752.7656-1-vasant.hegde@xxxxxxx
Signed-off-by: Joerg Roedel <jroedel@xxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
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 d3b39d0416fa3..46bf0744721dd 100644
--- a/drivers/iommu/amd/iommu.c
+++ b/drivers/iommu/amd/iommu.c
@@ -2394,12 +2394,17 @@ 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;
}
--
2.39.2
