OvmfPkg/XenAcpiPlatformDxe: remove delayed ACPI table installation

Because "PcdPciDisableBusEnumeration" is always TRUE in the OvmfXen
platform, we can remove the delayed ACPI table installation from
XenAcpiPlatformDxe. A number of dependencies become useless this way;
remove them too.

(Note that, conversely, in the QemuFwCfgAcpiPlatformDxe driver, we
*cannot* assume that "PcdPciDisableBusEnumeration" is always FALSE,
regardless of Xen: in the ArmVirtQemu platform, the PCD may carry either
FALSE or TRUE, dependent on whether or not the QEMU "virt" machine
configuration includes a PCIe host controller, respectively.)

Cc: Anthony Perard <anthony.perard@citrix.com>
Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Julien Grall <julien@xen.org>
Cc: Philippe Mathieu-Daudé <philmd@redhat.com>
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=2122
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Message-Id: <20210526201446.12554-21-lersek@redhat.com>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>

OvmfPkg/XenAcpiPlatformDxe/EntryPoint.c

@@ -7,9 +7,7 @@
   SPDX-License-Identifier: BSD-2-Clause-Patent
 **/
 
-#include <Guid/RootBridgesConnectedEventGroup.h> // gRootBridgesConnectedEve...
+#include <Library/DebugLib.h>                    // ASSERT_EFI_ERROR()
-#include <Library/DebugLib.h>                    // DEBUG()
-#include <Library/PcdLib.h>                      // PcdGetBool()
 #include <Library/UefiBootServicesTableLib.h>    // gBS
 #include <Protocol/AcpiTable.h>                  // EFI_ACPI_TABLE_PROTOCOL
 
@@ -34,27 +32,6 @@ FindAcpiTableProtocol (
 }
 
 
-STATIC
-VOID
-EFIAPI
-OnRootBridgesConnected (
-  IN EFI_EVENT Event,
-  IN VOID      *Context
-  )
-{
-  EFI_STATUS Status;
-
-  DEBUG ((DEBUG_INFO,
-    "%a: root bridges have been connected, installing ACPI tables\n",
-    __FUNCTION__));
-  Status = InstallAcpiTables (FindAcpiTableProtocol ());
-  if (EFI_ERROR (Status)) {
-    DEBUG ((DEBUG_ERROR, "%a: InstallAcpiTables: %r\n", __FUNCTION__, Status));
-  }
-  gBS->CloseEvent (Event);
-}
-
-
 EFI_STATUS
 EFIAPI
 AcpiPlatformEntryPoint (
@@ -62,34 +39,5 @@ AcpiPlatformEntryPoint (
   IN EFI_SYSTEM_TABLE   *SystemTable
   )
 {
-  EFI_STATUS Status;
-  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 ((DEBUG_INFO, "%a: PCI or its enumeration disabled, installing "
-      "ACPI tables\n", __FUNCTION__));
   return InstallAcpiTables (FindAcpiTableProtocol ());
-  }
-
-  //
-  // 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->CreateEventEx (EVT_NOTIFY_SIGNAL, TPL_CALLBACK,
-                  OnRootBridgesConnected, NULL /* Context */,
-                  &gRootBridgesConnectedEventGroupGuid, &RootBridgesConnected);
-  if (!EFI_ERROR (Status)) {
-    DEBUG ((DEBUG_INFO,
-      "%a: waiting for root bridges to be connected, registered callback\n",
-      __FUNCTION__));
-  }
-
-  return Status;
 }

OvmfPkg/XenAcpiPlatformDxe/XenAcpiPlatformDxe.inf

@@ -28,14 +28,12 @@
   Xen.c
 
 [Packages]
-  MdeModulePkg/MdeModulePkg.dec
   MdePkg/MdePkg.dec
   OvmfPkg/OvmfPkg.dec
 
 [LibraryClasses]
   BaseLib
   DebugLib
-  PcdLib
   UefiBootServicesTableLib
   UefiDriverEntryPoint
   XenPlatformLib
@@ -43,11 +41,5 @@
 [Protocols]
   gEfiAcpiTableProtocolGuid                     # PROTOCOL ALWAYS_CONSUMED
 
-[Guids]
-  gRootBridgesConnectedEventGroupGuid
-
-[Pcd]
-  gEfiMdeModulePkgTokenSpaceGuid.PcdPciDisableBusEnumeration
-
 [Depex]
   gEfiAcpiTableProtocolGuid