NVIDIA: SAUCE: iommu/arm-smmu-v3: Use identity domain for ASPEED BMC devices

ASPEED BMC devices behind an AST1150 PCIe-to-PCI bridge receive DMA
from BMC firmware using host physical addresses that bypass the
kernel's DMA API entirely.

When these devices are assigned a DMA translated domain, the SMMU
generates F_TRANSLATION faults because the BMC's physical addresses
have no corresponding IOVA mappings in the SMMU page tables.

Fix this by returning IOMMU_DOMAIN_IDENTITY for PCI devices whose
parent bridge has both the PCI_BRIDGE_NO_ALIASES flag and an ASPEED
vendor ID, so the SMMU passes BMC DMA transactions through
untranslated.

Signed-off-by: Koba Ko <kobak@nvidia.com>

Author: kobak2026

drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c

@@ -3774,6 +3774,19 @@ static int arm_smmu_def_domain_type(struct device *dev)
 		if (IS_HISI_PTT_DEVICE(pdev))
 			return IOMMU_DOMAIN_IDENTITY;
 
+		/*
+		 * ASPEED BMC devices behind an AST1150 PCIe-to-PCI bridge
+		 * receive DMA from BMC firmware using host physical addresses
+		 * that bypass the kernel DMA API.  Use identity mapping so
+		 * the SMMU passes these transactions through untranslated.
+		 */
+		if (pdev->bus->self &&
+		    (pdev->bus->self->dev_flags &
+		     PCI_DEV_FLAGS_PCI_BRIDGE_NO_ALIASES) &&
+		    pdev->bus->self->vendor == PCI_VENDOR_ID_ASPEED &&
+		    pdev->bus->self->device == 0x1150)
+			return IOMMU_DOMAIN_IDENTITY;
+
 		if (pdev->vendor == PCI_VENDOR_ID_NVIDIA &&
 		    (pdev->device == 0x2E12 || pdev->device == 0x2E2A ||
 		     pdev->device == 0x2E2B))