1 files changed, 39 insertions, 7 deletions

diff --git a/drivers/xen/grant-dma-ops.c b/drivers/xen/grant-dma-ops.c
index 1e797a043980..9784a77fa3c9 100644
--- a/drivers/xen/grant-dma-ops.c
+++ b/drivers/xen/grant-dma-ops.c
@@ -10,6 +10,7 @@
 #include <linux/module.h>
 #include <linux/dma-map-ops.h>
 #include <linux/of.h>
+#include <linux/pci.h>
 #include <linux/pfn.h>
 #include <linux/xarray.h>
 #include <linux/virtio_anchor.h>
@@ -292,15 +293,43 @@ static const struct dma_map_ops xen_grant_dma_ops = {
 	.dma_supported = xen_grant_dma_supported,
 };
 
+static struct device_node *xen_dt_get_node(struct device *dev)
+{
+	if (dev_is_pci(dev)) {
+		struct pci_dev *pdev = to_pci_dev(dev);
+		struct pci_bus *bus = pdev->bus;
+
+		/* Walk up to the root bus to look for PCI Host controller */
+		while (!pci_is_root_bus(bus))
+			bus = bus->parent;
+
+		return of_node_get(bus->bridge->parent->of_node);
+	}
+
+	return of_node_get(dev->of_node);
+}
+
 static int xen_dt_grant_init_backend_domid(struct device *dev,
+					   struct device_node *np,
 					   domid_t *backend_domid)
 {
-	struct of_phandle_args iommu_spec;
+	struct of_phandle_args iommu_spec = { .args_count = 1 };
 
-	if (of_parse_phandle_with_args(dev->of_node, "iommus", "#iommu-cells",
-			0, &iommu_spec)) {
-		dev_dbg(dev, "Cannot parse iommus property\n");
-		return -ESRCH;
+	if (dev_is_pci(dev)) {
+		struct pci_dev *pdev = to_pci_dev(dev);
+		u32 rid = PCI_DEVID(pdev->bus->number, pdev->devfn);
+
+		if (of_map_id(np, rid, "iommu-map", "iommu-map-mask", &iommu_spec.np,
+				iommu_spec.args)) {
+			dev_dbg(dev, "Cannot translate ID\n");
+			return -ESRCH;
+		}
+	} else {
+		if (of_parse_phandle_with_args(np, "iommus", "#iommu-cells",
+				0, &iommu_spec)) {
+			dev_dbg(dev, "Cannot parse iommus property\n");
+			return -ESRCH;
+		}
 	}
 
 	if (!of_device_is_compatible(iommu_spec.np, "xen,grant-dma") ||
@@ -324,10 +353,13 @@ static int xen_dt_grant_init_backend_domid(struct device *dev,
 static int xen_grant_init_backend_domid(struct device *dev,
 					domid_t *backend_domid)
 {
+	struct device_node *np;
 	int ret = -ENODEV;
 
-	if (dev->of_node) {
-		ret = xen_dt_grant_init_backend_domid(dev, backend_domid);
+	np = xen_dt_get_node(dev);
+	if (np) {
+		ret = xen_dt_grant_init_backend_domid(dev, np, backend_domid);
+		of_node_put(np);
 	} else if (IS_ENABLED(CONFIG_XEN_VIRTIO_FORCE_GRANT) || xen_pv_domain()) {
 		dev_info(dev, "Using dom0 as backend\n");
 		*backend_domid = 0;