[edk2,wave,1,v2,5/6] OvmfPkg: AcpiPlatformDxe: when PCI is enabled, wait for Platform BDS's cue

diff --git a/OvmfPkg/AcpiPlatformDxe/AcpiPlatformDxe.inf b/OvmfPkg/AcpiPlatformDxe/AcpiPlatformDxe.inf
index 055f3ad0ee0f..8e98053994eb 100644
--- a/OvmfPkg/AcpiPlatformDxe/AcpiPlatformDxe.inf
+++ b/OvmfPkg/AcpiPlatformDxe/AcpiPlatformDxe.inf
@@ -53,18 +53,18 @@  [LibraryClasses]
   MemoryAllocationLib
   BaseLib
   DxeServicesTableLib
   OrderedCollectionLib
 
 [Protocols]
   gEfiAcpiTableProtocolGuid                     # PROTOCOL ALWAYS_CONSUMED
-  gEfiPciEnumerationCompleteProtocolGuid        # PROTOCOL SOMETIMES_CONSUMED
 
 [Guids]
   gEfiXenInfoGuid
+  gRootBridgesConnectedEventGroupGuid
 
 [Pcd]
   gEfiMdeModulePkgTokenSpaceGuid.PcdAcpiTableStorageFile
   gEfiMdeModulePkgTokenSpaceGuid.PcdPciDisableBusEnumeration
   gUefiCpuPkgTokenSpaceGuid.PcdCpuLocalApicBaseAddress
   gPcAtChipsetPkgTokenSpaceGuid.Pcd8259LegacyModeEdgeLevel
   gUefiOvmfPkgTokenSpaceGuid.PcdOvmfFdBaseAddress
diff --git a/OvmfPkg/AcpiPlatformDxe/QemuFwCfgAcpiPlatformDxe.inf b/OvmfPkg/AcpiPlatformDxe/QemuFwCfgAcpiPlatformDxe.inf
index 22ce165852f9..c073b2a47ec6 100644
--- a/OvmfPkg/AcpiPlatformDxe/QemuFwCfgAcpiPlatformDxe.inf
+++ b/OvmfPkg/AcpiPlatformDxe/QemuFwCfgAcpiPlatformDxe.inf
@@ -43,14 +43,16 @@  [LibraryClasses]
   OrderedCollectionLib
   QemuFwCfgLib
   UefiBootServicesTableLib
   UefiDriverEntryPoint
 
 [Protocols]
   gEfiAcpiTableProtocolGuid                     # PROTOCOL ALWAYS_CONSUMED
-  gEfiPciEnumerationCompleteProtocolGuid        # PROTOCOL SOMETIMES_CONSUMED
+
+[Guids]
+  gRootBridgesConnectedEventGroupGuid
 
 [Pcd]
   gEfiMdeModulePkgTokenSpaceGuid.PcdPciDisableBusEnumeration
 
 [Depex]
   gEfiAcpiTableProtocolGuid
diff --git a/OvmfPkg/AcpiPlatformDxe/EntryPoint.c b/OvmfPkg/AcpiPlatformDxe/EntryPoint.c
index d713b0d44b1b..1bfd31a0371a 100644
--- a/OvmfPkg/AcpiPlatformDxe/EntryPoint.c
+++ b/OvmfPkg/AcpiPlatformDxe/EntryPoint.c
@@ -9,15 +9,15 @@ 
   distribution.  The full text of the license may be found at
   http://opensource.org/licenses/bsd-license.php
 
   THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, WITHOUT
   WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
 **/
 
-#include <Protocol/PciEnumerationComplete.h>
+#include <Guid/RootBridgesConnectedEventGroup.h>
 #include "AcpiPlatform.h"
 
 STATIC
 EFI_ACPI_TABLE_PROTOCOL *
 FindAcpiTableProtocol (
   VOID
   )
@@ -34,22 +34,23 @@  FindAcpiTableProtocol (
   return AcpiTable;
 }
 
 
 STATIC
 VOID
 EFIAPI
-OnPciEnumerated (
+OnRootBridgesConnected (
   IN EFI_EVENT Event,
   IN VOID      *Context
   )
 {
   EFI_STATUS Status;
 
-  DEBUG ((EFI_D_INFO, "%a: PCI enumeration complete, installing ACPI tables\n",
+  DEBUG ((EFI_D_INFO,
+    "%a: root bridges have been connected, installing ACPI tables\n",
     __FUNCTION__));
   Status = InstallAcpiTables (FindAcpiTableProtocol ());
   if (EFI_ERROR (Status)) {
     DEBUG ((EFI_D_ERROR, "%a: InstallAcpiTables: %r\n", __FUNCTION__, Status));
   }
   gBS->CloseEvent (Event);
 }
@@ -59,58 +60,37 @@  EFI_STATUS
 EFIAPI
 AcpiPlatformEntryPoint (
   IN EFI_HANDLE         ImageHandle,
   IN EFI_SYSTEM_TABLE   *SystemTable
   )
 {
   EFI_STATUS Status;
-  VOID       *Interface;
-  EFI_EVENT  PciEnumerated;
-  VOID       *Registration;
+  EFI_EVENT  RootBridgesConnected;
 
   //
   // If the platform doesn't support PCI, or PCI enumeration has been disabled,
   // install the tables at once, and let the entry point's return code reflect
   // the full functionality.
   //
   if (PcdGetBool (PcdPciDisableBusEnumeration)) {
     DEBUG ((EFI_D_INFO, "%a: PCI or its enumeration disabled, installing "
       "ACPI tables\n", __FUNCTION__));
     return InstallAcpiTables (FindAcpiTableProtocol ());
   }
 
   //
-  // Similarly, if PCI enumeration has already completed, install the tables
-  // immediately.
+  // Otherwise, delay installing the ACPI tables until root bridges are
+  // connected. The entry point's return status will only reflect the callback
+  // setup. (Note that we're a DXE_DRIVER; our entry point function is invoked
+  // strictly before BDS is entered and can connect the root bridges.)
   //
-  Status = gBS->LocateProtocol (&gEfiPciEnumerationCompleteProtocolGuid,
-                  NULL /* Registration */, &Interface);
+  Status = gBS->CreateEventEx (EVT_NOTIFY_SIGNAL, TPL_CALLBACK,
+                  OnRootBridgesConnected, NULL /* Context */,
+                  &gRootBridgesConnectedEventGroupGuid, &RootBridgesConnected);
   if (!EFI_ERROR (Status)) {
-    DEBUG ((EFI_D_INFO, "%a: PCI enumeration already complete, "
-      "installing ACPI tables\n", __FUNCTION__));
-    return InstallAcpiTables (FindAcpiTableProtocol ());
-  }
-  ASSERT (Status == EFI_NOT_FOUND);
-
-  //
-  // Otherwise, delay installing the ACPI tables until PCI enumeration
-  // completes. The entry point's return status will only reflect the callback
-  // setup.
-  //
-  Status = gBS->CreateEvent (EVT_NOTIFY_SIGNAL, TPL_CALLBACK, OnPciEnumerated,
-                  NULL /* Context */, &PciEnumerated);
-  if (EFI_ERROR (Status)) {
-    return Status;
-  }
-
-  Status = gBS->RegisterProtocolNotify (
-                  &gEfiPciEnumerationCompleteProtocolGuid, PciEnumerated,
-                  &Registration);
-  if (EFI_ERROR (Status)) {
-    gBS->CloseEvent (PciEnumerated);
-  } else {
-    DEBUG ((EFI_D_INFO, "%a: PCI enumeration pending, registered callback\n",
+    DEBUG ((EFI_D_INFO,
+      "%a: waiting for root bridges to be connected, registered callback\n",
       __FUNCTION__));
   }
 
   return Status;
 }