xen/arm: Add linux,pci-domain property for hwdom if not available.

If the property is not present in the device tree node for host bridge,
XEN while creating the dtb for hwdom will create this property and
assigns the already allocated segment to the host bridge
so that XEN and linux will have the same segment for the host bridges.

Signed-off-by: Rahul Singh <rahul.singh@arm.com>
Reviewed-by: Bertrand Marquis <bertrand.marquis@arm.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>

xen/arch/arm/domain_build.c

@@ -747,6 +747,22 @@ static int __init write_properties(struct domain *d, struct kernel_info *kinfo,
             return res;
     }
 
+    if ( is_pci_passthrough_enabled() && dt_device_type_is_equal(node, "pci") )
+    {
+        if ( !dt_find_property(node, "linux,pci-domain", NULL) )
+        {
+            uint16_t segment;
+
+            res = pci_get_host_bridge_segment(node, &segment);
+            if ( res < 0 )
+                return res;
+
+            res = fdt_property_cell(kinfo->fdt, "linux,pci-domain", segment);
+            if ( res )
+                return res;
+        }
+    }
+
     /*
      * Override the property "status" to disable the device when it's
      * marked for passthrough.

xen/arch/arm/pci/pci-host-common.c

@@ -271,6 +271,27 @@ struct pci_host_bridge *pci_find_host_bridge(uint16_t segment, uint8_t bus)
 
     return NULL;
 }
+
+/*
+ * This function will lookup an hostbridge based on config space address.
+ */
+int pci_get_host_bridge_segment(const struct dt_device_node *node,
+                                uint16_t *segment)
+{
+    struct pci_host_bridge *bridge;
+
+    list_for_each_entry( bridge, &pci_host_bridges, node )
+    {
+        if ( bridge->dt_node != node )
+            continue;
+
+        *segment = bridge->segment;
+        return 0;
+    }
+
+    return -EINVAL;
+}
+
 /*
  * Local variables:
  * mode: C

xen/include/asm-arm/pci.h

@@ -98,6 +98,8 @@ void __iomem *pci_ecam_map_bus(struct pci_host_bridge *bridge,
                                pci_sbdf_t sbdf, uint32_t where);
 struct pci_host_bridge *pci_find_host_bridge(uint16_t segment, uint8_t bus);
 struct dt_device_node *pci_find_host_bridge_node(struct device *dev);
+int pci_get_host_bridge_segment(const struct dt_device_node *node,
+                                uint16_t *segment);
 
 static always_inline bool is_pci_passthrough_enabled(void)
 {
@@ -119,5 +121,12 @@ struct pci_dev;
 
 static inline void arch_pci_init_pdev(struct pci_dev *pdev) {}
 
+static inline int pci_get_host_bridge_segment(const struct dt_device_node *node,
+                                              uint16_t *segment)
+{
+    ASSERT_UNREACHABLE();
+    return -EINVAL;
+}
+
 #endif  /*!CONFIG_HAS_PCI*/
 #endif /* __ARM_PCI_H__ */