[Xen-devel] [PATCH] OvmfPkg: AcpiPlatformDxe: PCI enumeration may be disabled

[Laszlo Ersek <lersek@xxxxxxxxxx>]

SVN r16411 delayed ACPI table installation until PCI enumeration was
complete, because on QEMU the ACPI-related fw_cfg files should only be
downloaded after PCI enumeration.

However, InitializeXen() in "OvmfPkg/PlatformPei/Xen.c" sets
PcdPciDisableBusEnumeration to TRUE. This causes
PciBusDriverBindingStart() in "MdeModulePkg/Bus/Pci/PciBusDxe/PciBus.c" to
set gFullEnumeration to FALSE, which in turn makes PciEnumerator() in
"MdeModulePkg/Bus/Pci/PciBusDxe/PciEnumerator.c" branch to
PciEnumeratorLight(). The installation of
EFI_PCI_ENUMERATION_COMPLETE_PROTOCOL at the end of PciEnumerator() is not
reached.

Which means that starting with SVN r16411, AcpiPlatformDxe is never
dispatched on Xen.

This patch replaces the EFI_PCI_ENUMERATION_COMPLETE_PROTOCOL depex with a
matching protocol registration callback for the PCI enumeration enabled
(ie. QEMU) case. When PCI enumeration is disabled (ie. when running on
Xen), AcpiPlatformDxe doesn't wait for
EFI_PCI_ENUMERATION_COMPLETE_PROTOCOL.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@xxxxxxxxxx>
---
 OvmfPkg/AcpiPlatformDxe/AcpiPlatformDxe.inf |  4 +-
 OvmfPkg/AcpiPlatformDxe/AcpiPlatform.c      | 84 +++++++++++++++++++++++------
 2 files changed, 72 insertions(+), 16 deletions(-)

diff --git a/OvmfPkg/AcpiPlatformDxe/AcpiPlatformDxe.inf 
b/OvmfPkg/AcpiPlatformDxe/AcpiPlatformDxe.inf
index 53292bf..6b2c9d2 100644
--- a/OvmfPkg/AcpiPlatformDxe/AcpiPlatformDxe.inf
+++ b/OvmfPkg/AcpiPlatformDxe/AcpiPlatformDxe.inf
@@ -56,16 +56,18 @@
 
 [Protocols]
   gEfiAcpiTableProtocolGuid                     # PROTOCOL ALWAYS_CONSUMED
+  gEfiPciEnumerationCompleteProtocolGuid        # PROTOCOL SOMETIMES_CONSUMED
 
 [Guids]
   gEfiXenInfoGuid
 
 [Pcd]
   gEfiMdeModulePkgTokenSpaceGuid.PcdAcpiTableStorageFile
+  gEfiMdeModulePkgTokenSpaceGuid.PcdPciDisableBusEnumeration
   gUefiCpuPkgTokenSpaceGuid.PcdCpuLocalApicBaseAddress
   gPcAtChipsetPkgTokenSpaceGuid.Pcd8259LegacyModeEdgeLevel
   gUefiOvmfPkgTokenSpaceGuid.PcdOvmfFdBaseAddress
 
 [Depex]
-  gEfiAcpiTableProtocolGuid AND gEfiPciEnumerationCompleteProtocolGuid
+  gEfiAcpiTableProtocolGuid
 
diff --git a/OvmfPkg/AcpiPlatformDxe/AcpiPlatform.c 
b/OvmfPkg/AcpiPlatformDxe/AcpiPlatform.c
index 11f0ca8..9823eba 100644
--- a/OvmfPkg/AcpiPlatformDxe/AcpiPlatform.c
+++ b/OvmfPkg/AcpiPlatformDxe/AcpiPlatform.c
@@ -12,6 +12,7 @@
 
 **/
 
+#include <Protocol/PciEnumerationComplete.h>
 #include "AcpiPlatform.h"
 
 EFI_STATUS
@@ -221,6 +222,47 @@ FindAcpiTablesInFv (
   return EFI_SUCCESS;
 }
 
+STATIC
+EFI_STATUS
+EFIAPI
+InstallTables (
+  VOID
+  )
+{
+  EFI_STATUS              Status;
+  EFI_ACPI_TABLE_PROTOCOL *AcpiTable;
+
+  Status = gBS->LocateProtocol (&gEfiAcpiTableProtocolGuid,
+                  NULL /* Registration */, (VOID **)&AcpiTable);
+  if (EFI_ERROR (Status)) {
+    return EFI_ABORTED;
+  }
+
+  if (XenDetected ()) {
+    Status = InstallXenTables (AcpiTable);
+  } else {
+    Status = InstallAllQemuLinkedTables (AcpiTable);
+  }
+
+  if (EFI_ERROR (Status)) {
+    Status = FindAcpiTablesInFv (AcpiTable);
+  }
+
+  return Status;
+}
+
+STATIC
+VOID
+EFIAPI
+OnPciEnumerated (
+  IN EFI_EVENT Event,
+  IN VOID      *Context
+  )
+{
+  InstallTables ();
+  gBS->CloseEvent (Event);
+}
+
 /**
   Entrypoint of Acpi Platform driver.
 
@@ -239,31 +281,43 @@ AcpiPlatformEntryPoint (
   IN EFI_SYSTEM_TABLE   *SystemTable
   )
 {
-  EFI_STATUS                         Status;
-  EFI_ACPI_TABLE_PROTOCOL            *AcpiTable;
+  EFI_STATUS Status;
+  VOID       *Interface;
+  EFI_EVENT  PciEnumerated;
+  VOID       *Registration;
 
   //
-  // Find the AcpiTable protocol
+  // If PCI enumeration has been disabled, or it has already completed, install
+  // the tables at once, and let the entry point's return code reflect the full
+  // functionality.
   //
-  Status = gBS->LocateProtocol (
-                  &gEfiAcpiTableProtocolGuid,
-                  NULL,
-                  (VOID**)&AcpiTable
-                  );
-  if (EFI_ERROR (Status)) {
-    return EFI_ABORTED;
+  if (PcdGetBool (PcdPciDisableBusEnumeration)) {
+    return InstallTables ();
   }
 
-  if (XenDetected ()) {
-    Status = InstallXenTables (AcpiTable);
-  } else {
-    Status = InstallAllQemuLinkedTables (AcpiTable);
+  Status = gBS->LocateProtocol (&gEfiPciEnumerationCompleteProtocolGuid,
+                  NULL /* Registration */, &Interface);
+  if (!EFI_ERROR (Status)) {
+    return InstallTables ();
   }
+  ASSERT (Status == EFI_NOT_FOUND);
 
+  //
+  // Otherwise, delay the installation until PCI enumeration is complete. 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)) {
-    Status = FindAcpiTablesInFv (AcpiTable);
+    return Status;
   }
 
+  Status = gBS->RegisterProtocolNotify (
+                  &gEfiPciEnumerationCompleteProtocolGuid, PciEnumerated,
+                  &Registration);
+  if (EFI_ERROR (Status)) {
+    gBS->CloseEvent (PciEnumerated);
+  }
   return Status;
 }
 
-- 
1.8.3.1


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