iommu/vt-d: Expose ISA direct mapping region via iommu_get_resv_regions

To support mapping ISA region via iommu_group_create_direct_mappings,
make sure its exposed by iommu_get_resv_regions.

Signed-off-by: James Sewart <jamessewart@arista.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

Author: LuBaolu

drivers/iommu/intel-iommu.c

@@ -5479,6 +5479,19 @@ static void intel_iommu_get_resv_regions(struct device *device,
 	}
 	rcu_read_unlock();
 
+#ifdef CONFIG_INTEL_IOMMU_FLOPPY_WA
+	if (dev_is_pci(device)) {
+		struct pci_dev *pdev = to_pci_dev(device);
+
+		if ((pdev->class >> 8) == PCI_CLASS_BRIDGE_ISA) {
+			reg = iommu_alloc_resv_region(0, 1UL << 24, 0,
+						      IOMMU_RESV_DIRECT);
+			if (reg)
+				list_add_tail(&reg->list, head);
+		}
+	}
+#endif /* CONFIG_INTEL_IOMMU_FLOPPY_WA */
+
 	reg = iommu_alloc_resv_region(IOAPIC_RANGE_START,
 				      IOAPIC_RANGE_END - IOAPIC_RANGE_START + 1,
 				      0, IOMMU_RESV_MSI);