+/**\r
+ Utility function to return all the root bridge instances in an array.\r
+\r
+ @param[out] Count The number of root bridge instances.\r
+\r
+ @param[in] Attributes Initial attributes.\r
+\r
+ @param[in] AllocAttributes Allocation attributes.\r
+\r
+ @param[in] Io IO aperture.\r
+\r
+ @param[in] Mem MMIO aperture.\r
+\r
+ @param[in] MemAbove4G MMIO aperture above 4G.\r
+\r
+ @param[in] PMem Prefetchable MMIO aperture.\r
+\r
+ @param[in] PMemAbove4G Prefetchable MMIO aperture above 4G.\r
+\r
+ @return All the root bridge instances in an array.\r
+**/\r
+PCI_ROOT_BRIDGE *\r
+EFIAPI\r
+PciHostBridgeUtilityGetRootBridges (\r
+ OUT UINTN *Count,\r
+ IN UINT64 Attributes,\r
+ IN UINT64 AllocationAttributes,\r
+ IN PCI_ROOT_BRIDGE_APERTURE *Io,\r
+ IN PCI_ROOT_BRIDGE_APERTURE *Mem,\r
+ IN PCI_ROOT_BRIDGE_APERTURE *MemAbove4G,\r
+ IN PCI_ROOT_BRIDGE_APERTURE *PMem,\r
+ IN PCI_ROOT_BRIDGE_APERTURE *PMemAbove4G\r
+ )\r
+{\r
+ EFI_STATUS Status;\r
+ FIRMWARE_CONFIG_ITEM FwCfgItem;\r
+ UINTN FwCfgSize;\r
+ UINT64 ExtraRootBridges;\r
+ PCI_ROOT_BRIDGE *Bridges;\r
+ UINTN Initialized;\r
+ UINTN LastRootBridgeNumber;\r
+ UINTN RootBridgeNumber;\r
+\r
+ *Count = 0;\r
+\r
+ //\r
+ // QEMU provides the number of extra root buses, shortening the exhaustive\r
+ // search below. If there is no hint, the feature is missing.\r
+ //\r
+ Status = QemuFwCfgFindFile ("etc/extra-pci-roots", &FwCfgItem, &FwCfgSize);\r
+ if (EFI_ERROR (Status) || FwCfgSize != sizeof ExtraRootBridges) {\r
+ ExtraRootBridges = 0;\r
+ } else {\r
+ QemuFwCfgSelectItem (FwCfgItem);\r
+ QemuFwCfgReadBytes (FwCfgSize, &ExtraRootBridges);\r
+\r
+ if (ExtraRootBridges > PCI_MAX_BUS) {\r
+ DEBUG ((DEBUG_ERROR, "%a: invalid count of extra root buses (%Lu) "\r
+ "reported by QEMU\n", __FUNCTION__, ExtraRootBridges));\r
+ return NULL;\r
+ }\r
+ DEBUG ((DEBUG_INFO, "%a: %Lu extra root buses reported by QEMU\n",\r
+ __FUNCTION__, ExtraRootBridges));\r
+ }\r
+\r
+ //\r
+ // Allocate the "main" root bridge, and any extra root bridges.\r
+ //\r
+ Bridges = AllocatePool ((1 + (UINTN)ExtraRootBridges) * sizeof *Bridges);\r
+ if (Bridges == NULL) {\r
+ DEBUG ((DEBUG_ERROR, "%a: %r\n", __FUNCTION__, EFI_OUT_OF_RESOURCES));\r
+ return NULL;\r
+ }\r
+ Initialized = 0;\r
+\r
+ //\r
+ // The "main" root bus is always there.\r
+ //\r
+ LastRootBridgeNumber = 0;\r
+\r
+ //\r
+ // Scan all other root buses. If function 0 of any device on a bus returns a\r
+ // VendorId register value different from all-bits-one, then that bus is\r
+ // alive.\r
+ //\r
+ for (RootBridgeNumber = 1;\r
+ RootBridgeNumber <= PCI_MAX_BUS && Initialized < ExtraRootBridges;\r
+ ++RootBridgeNumber) {\r
+ UINTN Device;\r
+\r
+ for (Device = 0; Device <= PCI_MAX_DEVICE; ++Device) {\r
+ if (PciRead16 (PCI_LIB_ADDRESS (RootBridgeNumber, Device, 0,\r
+ PCI_VENDOR_ID_OFFSET)) != MAX_UINT16) {\r
+ break;\r
+ }\r
+ }\r
+ if (Device <= PCI_MAX_DEVICE) {\r
+ //\r
+ // Found the next root bus. We can now install the *previous* one,\r
+ // because now we know how big a bus number range *that* one has, for any\r
+ // subordinate buses that might exist behind PCI bridges hanging off it.\r
+ //\r
+ Status = PciHostBridgeUtilityInitRootBridge (\r
+ Attributes,\r
+ Attributes,\r
+ AllocationAttributes,\r
+ FALSE,\r
+ PcdGet16 (PcdOvmfHostBridgePciDevId) != INTEL_Q35_MCH_DEVICE_ID,\r
+ (UINT8) LastRootBridgeNumber,\r
+ (UINT8) (RootBridgeNumber - 1),\r
+ Io,\r
+ Mem,\r
+ MemAbove4G,\r
+ PMem,\r
+ PMemAbove4G,\r
+ &Bridges[Initialized]\r
+ );\r
+ if (EFI_ERROR (Status)) {\r
+ goto FreeBridges;\r
+ }\r
+ ++Initialized;\r
+ LastRootBridgeNumber = RootBridgeNumber;\r
+ }\r
+ }\r
+\r
+ //\r
+ // Install the last root bus (which might be the only, ie. main, root bus, if\r
+ // we've found no extra root buses).\r
+ //\r
+ Status = PciHostBridgeUtilityInitRootBridge (\r
+ Attributes,\r
+ Attributes,\r
+ AllocationAttributes,\r
+ FALSE,\r
+ PcdGet16 (PcdOvmfHostBridgePciDevId) != INTEL_Q35_MCH_DEVICE_ID,\r
+ (UINT8) LastRootBridgeNumber,\r
+ PCI_MAX_BUS,\r
+ Io,\r
+ Mem,\r
+ MemAbove4G,\r
+ PMem,\r
+ PMemAbove4G,\r
+ &Bridges[Initialized]\r
+ );\r
+ if (EFI_ERROR (Status)) {\r
+ goto FreeBridges;\r
+ }\r
+ ++Initialized;\r
+\r
+ *Count = Initialized;\r
+ return Bridges;\r
+\r
+FreeBridges:\r
+ while (Initialized > 0) {\r
+ --Initialized;\r
+ PciHostBridgeUtilityUninitRootBridge (&Bridges[Initialized]);\r
+ }\r
+\r
+ FreePool (Bridges);\r
+ return NULL;\r
+}\r
+\r
+\r
+/**\r
+ Utility function to free root bridge instances array from\r
+ PciHostBridgeUtilityGetRootBridges().\r
+\r
+ @param[in] Bridges The root bridge instances array.\r
+ @param[in] Count The count of the array.\r
+**/\r
+VOID\r
+EFIAPI\r
+PciHostBridgeUtilityFreeRootBridges (\r
+ IN PCI_ROOT_BRIDGE *Bridges,\r
+ IN UINTN Count\r
+ )\r
+{\r
+ if (Bridges == NULL && Count == 0) {\r
+ return;\r
+ }\r
+ ASSERT (Bridges != NULL && Count > 0);\r
+\r
+ do {\r
+ --Count;\r
+ PciHostBridgeUtilityUninitRootBridge (&Bridges[Count]);\r
+ } while (Count > 0);\r
+\r
+ FreePool (Bridges);\r
+}\r
+\r
+\r