[PATCH 7/8] acpi-build: Create PCI topology using amd iommu root bus

[Sairaj Kodilkar <sarunkod@amd.com>]

Current AMD IOMMU ACPI build adds all the devices and buses under the
IVHD. In order to support the IOMMU attached on a non system bus and
serving only child devices of that bus, start exploring devices from the
child bus. Also, use child list provided by the PCIBus, instead of
iterating over all the objects in the qemu to find pci bridges.

Signed-off-by: Sairaj Kodilkar <sarunkod@amd.com>
---
 hw/i386/acpi-build.c | 142 ++++++++++++++++++++++---------------------
 1 file changed, 74 insertions(+), 68 deletions(-)

diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
index 8837b69687d1..ed944c819406 100644
--- a/hw/i386/acpi-build.c
+++ b/hw/i386/acpi-build.c
@@ -1760,83 +1760,89 @@ insert_ivhd(PCIBus *bus, PCIDevice *dev, void *opaque)
     /* "Select" IVHD entry, type 0x2 */
     entry = PCI_BUILD_BDF(pci_bus_num(bus), dev->devfn) << 8 | 0x2;
     build_append_int_noprefix(table_data, entry, 4);
+}
 
-    if (object_dynamic_cast(OBJECT(dev), TYPE_PCI_BRIDGE)) {
-        PCIBus *sec_bus = pci_bridge_get_sec_bus(PCI_BRIDGE(dev));
-        uint8_t sec = pci_bus_num(sec_bus);
-        uint8_t sub = dev->config[PCI_SUBORDINATE_BUS];
-
-        if (pci_bus_is_express(sec_bus)) {
-            /*
-             * Walk the bus if there are subordinates, otherwise use a range
-             * to cover an entire leaf bus.  We could potentially also use a
-             * range for traversed buses, but we'd need to take care not to
-             * create both Select and Range entries covering the same device.
-             * This is easier and potentially more compact.
-             *
-             * An example bare metal system seems to use Select entries for
-             * root ports without a slot (ie. built-ins) and Range entries
-             * when there is a slot.  The same system also only hard-codes
-             * the alias range for an onboard PCIe-to-PCI bridge, apparently
-             * making no effort to support nested bridges.  We attempt to
-             * be more thorough here.
-             */
-            if (sec == sub) { /* leaf bus */
-                /* "Start of Range" IVHD entry, type 0x3 */
-                entry = PCI_BUILD_BDF(sec, PCI_DEVFN(0, 0)) << 8 | 0x3;
-                build_append_int_noprefix(table_data, entry, 4);
-                /* "End of Range" IVHD entry, type 0x4 */
-                entry = PCI_BUILD_BDF(sub, PCI_DEVFN(31, 7)) << 8 | 0x4;
-                build_append_int_noprefix(table_data, entry, 4);
-            } else {
-                pci_for_each_device(sec_bus, sec, insert_ivhd, table_data);
-            }
-        } else {
-            /*
-             * If the secondary bus is conventional, then we need to create an
-             * Alias range for everything downstream.  The range covers the
-             * first devfn on the secondary bus to the last devfn on the
-             * subordinate bus.  The alias target depends on legacy versus
-             * express bridges, just as in pci_device_iommu_address_space().
-             * DeviceIDa vs DeviceIDb as per the AMD IOMMU spec.
-             */
-            uint16_t dev_id_a, dev_id_b;
-
-            dev_id_a = PCI_BUILD_BDF(sec, PCI_DEVFN(0, 0));
+/*
+ * Insert IVHD entry for device and recurse, insert alias, or insert range as
+ * necessary for the PCI topology.
+ */
+static void add_ivhd_entries_from_bus(PCIBus *bus, GArray *table_data)
+{
+    uint8_t sub;
+    uint32_t entry;
+    PCIBus *child_bus;
+    PCIDevice *parent_dev;
 
-            if (pci_is_express(dev) &&
-                pcie_cap_get_type(dev) == PCI_EXP_TYPE_PCI_BRIDGE) {
-                dev_id_b = dev_id_a;
-            } else {
-                dev_id_b = PCI_BUILD_BDF(pci_bus_num(bus), dev->devfn);
-            }
+    if (!bus->parent_dev) {
+        goto select_devices;
+    }
 
-            /* "Alias Start of Range" IVHD entry, type 0x43, 8 bytes */
-            build_append_int_noprefix(table_data, dev_id_a << 8 | 0x43, 4);
-            build_append_int_noprefix(table_data, dev_id_b << 8 | 0x0, 4);
+    parent_dev = bus->parent_dev;
+    sub = parent_dev->config[PCI_SUBORDINATE_BUS];
 
-            /* "End of Range" IVHD entry, type 0x4 */
-            entry = PCI_BUILD_BDF(sub, PCI_DEVFN(31, 7)) << 8 | 0x4;
-            build_append_int_noprefix(table_data, entry, 4);
+    if (pci_bus_is_express(bus)) {
+        /*
+         * Walk the bus if there are subordinates, otherwise use a range
+         * to cover an entire leaf bus.  We could potentially also use a
+         * range for traversed buses, but we'd need to take care not to
+         * create both Select and Range entries covering the same device.
+         * This is easier and potentially more compact.
+         *
+         * An example bare metal system seems to use Select entries for
+         * root ports without a slot (ie. built-ins) and Range entries
+         * when there is a slot.  The same system also only hard-codes
+         * the alias range for an onboard PCIe-to-PCI bridge, apparently
+         * making no effort to support nested bridges.  We attempt to
+         * be more thorough here.
+         */
+        if (sub != pci_bus_num(bus)) {
+            goto select_devices;
         }
-    }
-}
+        /* "Start of Range" IVHD entry, type 0x3 */
+        entry = PCI_BUILD_BDF(sub, PCI_DEVFN(0, 0)) << 8 | 0x3;
+        build_append_int_noprefix(table_data, entry, 4);
+        /* "End of Range" IVHD entry, type 0x4 */
+        entry = PCI_BUILD_BDF(sub, PCI_DEVFN(31, 7)) << 8 | 0x4;
+        build_append_int_noprefix(table_data, entry, 4);
 
-/* For all PCI host bridges, walk and insert IVHD entries */
-static int
-ivrs_host_bridges(Object *obj, void *opaque)
-{
-    GArray *ivhd_blob = opaque;
+        return;
+    } else {
+        /*
+         * If the secondary bus is conventional, then we need to create an
+         * Alias range for everything downstream.  The range covers the
+         * first devfn on the secondary bus to the last devfn on the
+         * subordinate bus.  The alias target depends on legacy versus
+         * express bridges, just as in pci_device_iommu_address_space().
+         * DeviceIDa vs DeviceIDb as per the AMD IOMMU spec.
+         */
+        uint16_t dev_id_a, dev_id_b;
 
-    if (object_dynamic_cast(obj, TYPE_PCI_HOST_BRIDGE)) {
-        PCIBus *bus = PCI_HOST_BRIDGE(obj)->bus;
+        dev_id_a = PCI_BUILD_BDF(pci_bus_num(bus), PCI_DEVFN(0, 0));
 
-        if (bus && !pci_bus_bypass_iommu(bus)) {
-            pci_for_each_device_under_bus(bus, insert_ivhd, ivhd_blob);
+        if (pci_is_express(parent_dev) &&
+            pcie_cap_get_type(parent_dev) == PCI_EXP_TYPE_PCI_BRIDGE) {
+            dev_id_b = dev_id_a;
+        } else {
+            dev_id_b = PCI_BUILD_BDF(pci_bus_num(pci_get_bus(parent_dev)),
+                                     parent_dev->devfn);
         }
+
+        /* "Alias Start of Range" IVHD entry, type 0x43, 8 bytes */
+        build_append_int_noprefix(table_data, dev_id_a << 8 | 0x43, 4);
+        build_append_int_noprefix(table_data, dev_id_b << 8 | 0x0, 4);
+
+        /* "End of Range" IVHD entry, type 0x4 */
+        entry = PCI_BUILD_BDF(sub, PCI_DEVFN(31, 7)) << 8 | 0x4;
+        build_append_int_noprefix(table_data, entry, 4);
+        return;
     }
 
-    return 0;
+select_devices:
+    pci_for_each_device_under_bus(bus, insert_ivhd, table_data);
+
+    QLIST_FOREACH(child_bus, &bus->child, sibling) {
+        add_ivhd_entries_from_bus(child_bus, table_data);
+    }
 }
 
 static void
@@ -1867,8 +1873,8 @@ build_amd_iommu(GArray *table_data, BIOSLinker *linker, const char *oem_id,
      * blob further below.  Fall back to an entry covering all devices, which
      * is sufficient when no aliases are present.
      */
-    object_child_foreach_recursive(object_get_root(),
-                                   ivrs_host_bridges, ivhd_blob);
+    assert(s->root_bus);
+    add_ivhd_entries_from_bus(s->root_bus, ivhd_blob);
 
     if (!ivhd_blob->len) {
         /*
-- 
2.34.1