OvmfPkg: Introduce XenPlatformPei

Introduce XenPlatformPei, a copy of OvmfPkg/PlatformPei without some
of QEMU specific initialization, Xen does not support QemuFwCfg.

This new module will be adjusted to accommodate Xen PVH.

fw_cfg dependents that have been removed, which are dynamically skipped
when running PlatformPei on Xen:
- GetFirstNonAddress(): controlling the 64-bit PCI MMIO aperture via the
(experimental) "opt/ovmf/X-PciMmio64Mb" file
- GetFirstNonAddress(): honoring the hotplug DIMM area
("etc/reserved-memory-end") in the placement of the 64-bit PCI MMIO
aperture
- NoexecDxeInitialization() is removed, so PcdPropertiesTableEnable and
PcdSetNxForStack are left constant FALSE (not set dynamically from
fw_cfg "opt/ovmf/PcdXxxx")
- MaxCpuCountInitialization(), PublishPeiMemory(): the max CPU count is
not taken from the QemuFwCfgItemSmpCpuCount fw_cfg key;
PcdCpuMaxLogicalProcessorNumber is used intact and
PcdCpuApInitTimeOutInMicroSeconds is never changed or used.
- InitializeXenPlatform(), S3Verification(): S3 is assumed disabled (not
consulting "etc/system-states" via QemuFwCfgS3Enabled()).
- InstallFeatureControlCallback(): the feature control MSR is not set
from "etc/msr_feature_control"
(also removed FeatureControl.c as there is nothing been executed)

Also removed:
- SMRAM/TSEG-related low mem size adjusting (PcdSmmSmramRequire is
assumed FALSE) in PublishPeiMemory(),
- QemuInitializeRam() entirely,

Xen related changes:
- Have removed the module variable mXen, as it should be always true.
- Have the platform PEI initialization fails if Xen has not been
  detected.

Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=1689
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Message-Id: <20190813113119.14804-5-anthony.perard@citrix.com>

OvmfPkg/XenPlatformPei/ClearCache.c

@@ -0,0 +1,112 @@
+/**@file
+  Install a callback to clear cache on all processors.
+  This is for conformance with the TCG "Platform Reset Attack Mitigation
+  Specification". Because clearing the CPU caches at boot doesn't impact
+  performance significantly, do it unconditionally, for simplicity's
+  sake.
+
+  Copyright (C) 2018, Red Hat, Inc.
+  Copyright (c) 2019, Citrix Systems, Inc.
+
+  SPDX-License-Identifier: BSD-2-Clause-Patent
+**/
+
+#include <Library/CacheMaintenanceLib.h>
+#include <Library/DebugLib.h>
+#include <Library/PeiServicesLib.h>
+#include <Ppi/MpServices.h>
+
+#include "Platform.h"
+
+/**
+  Invalidate data & instruction caches.
+  All APs execute this function in parallel. The BSP executes the function
+  separately.
+
+  @param[in,out] WorkSpace  Pointer to the input/output argument workspace
+                            shared by all processors.
+**/
+STATIC
+VOID
+EFIAPI
+ClearCache (
+  IN OUT VOID *WorkSpace
+  )
+{
+  WriteBackInvalidateDataCache ();
+  InvalidateInstructionCache ();
+}
+
+/**
+  Notification function called when EFI_PEI_MP_SERVICES_PPI becomes available.
+
+  @param[in] PeiServices      Indirect reference to the PEI Services Table.
+  @param[in] NotifyDescriptor Address of the notification descriptor data
+                              structure.
+  @param[in] Ppi              Address of the PPI that was installed.
+
+  @return  Status of the notification. The status code returned from this
+           function is ignored.
+**/
+STATIC
+EFI_STATUS
+EFIAPI
+ClearCacheOnMpServicesAvailable (
+  IN EFI_PEI_SERVICES           **PeiServices,
+  IN EFI_PEI_NOTIFY_DESCRIPTOR  *NotifyDescriptor,
+  IN VOID                       *Ppi
+  )
+{
+  EFI_PEI_MP_SERVICES_PPI *MpServices;
+  EFI_STATUS              Status;
+
+  DEBUG ((DEBUG_INFO, "%a: %a\n", gEfiCallerBaseName, __FUNCTION__));
+
+  //
+  // Clear cache on all the APs in parallel.
+  //
+  MpServices = Ppi;
+  Status = MpServices->StartupAllAPs (
+                         (CONST EFI_PEI_SERVICES **)PeiServices,
+                         MpServices,
+                         ClearCache,          // Procedure
+                         FALSE,               // SingleThread
+                         0,                   // TimeoutInMicroSeconds: inf.
+                         NULL                 // ProcedureArgument
+                         );
+  if (EFI_ERROR (Status) && Status != EFI_NOT_STARTED) {
+    DEBUG ((DEBUG_ERROR, "%a: StartupAllAps(): %r\n", __FUNCTION__, Status));
+    return Status;
+  }
+
+  //
+  // Now clear cache on the BSP too.
+  //
+  ClearCache (NULL);
+  return EFI_SUCCESS;
+}
+
+//
+// Notification object for registering the callback, for when
+// EFI_PEI_MP_SERVICES_PPI becomes available.
+//
+STATIC CONST EFI_PEI_NOTIFY_DESCRIPTOR mMpServicesNotify = {
+  EFI_PEI_PPI_DESCRIPTOR_NOTIFY_CALLBACK | // Flags
+  EFI_PEI_PPI_DESCRIPTOR_TERMINATE_LIST,
+  &gEfiPeiMpServicesPpiGuid,               // Guid
+  ClearCacheOnMpServicesAvailable          // Notify
+};
+
+VOID
+InstallClearCacheCallback (
+  VOID
+  )
+{
+  EFI_STATUS           Status;
+
+  Status = PeiServicesNotifyPpi (&mMpServicesNotify);
+  if (EFI_ERROR (Status)) {
+    DEBUG ((DEBUG_ERROR, "%a: failed to set up MP Services callback: %r\n",
+      __FUNCTION__, Status));
+  }
+}