iommu/vt-d: Allocate reserved region for ISA with correct permission

Currently the reserved region for ISA is allocated with no
permissions. If a dma domain is being used, mapping this region will
fail. Set the permissions to DMA_PTE_READ|DMA_PTE_WRITE.

Cc: Joerg Roedel <jroedel@suse.de>
Cc: Lu Baolu <baolu.lu@linux.intel.com>
Cc: iommu@lists.linux-foundation.org
Cc: stable@vger.kernel.org # v5.3+
Fixes: d850c2e ("iommu/vt-d: Expose ISA direct mapping region via iommu_get_resv_regions")
Signed-off-by: Jerry Snitselaar <jsnitsel@redhat.com>
Acked-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

Author: snits

drivers/iommu/intel-iommu.c

@@ -5728,7 +5728,7 @@ static void intel_iommu_get_resv_regions(struct device *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,
+			reg = iommu_alloc_resv_region(0, 1UL << 24, prot,
 						   IOMMU_RESV_DIRECT_RELAXABLE);
 			if (reg)
 				list_add_tail(&reg->list, head);