UefiCpuPkg: CpuDxe: broadcast MTRR changes to APs

The Quark_EDKII_v1.1.0/IA32FamilyCpuBasePkg/CpuArchDxe
driver applies any MTRR changes to APs, if the
EFI_MP_SERVICES_PROTOCOL is available. We should do the same.

Additionally, the broadcast should occur at MP startup as well,
not only when MTRR settings are changed. The inspiration is
taken from

  Quark_EDKII_v1.1.0/IA32FamilyCpuBasePkg/CpuMpDxe/

(see the EarlyMpInit() function and its call sites in
"ProcessorConfig.c").

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jeff Fan <jeff.fan@intel.com>
Reviewed-by: Michael Kinney <michael.d.kinney@intel.com>

git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@18632 6f19259b-4bc3-4df7-8a09-765794883524

UefiCpuPkg/CpuDxe/CpuMp.h

@@ -643,5 +643,18 @@ ResetApStackless (
   IN UINT32 ProcessorId
   );
 
+/**
+  A minimal wrapper function that allows MtrrSetAllMtrrs() to be passed to
+  EFI_MP_SERVICES_PROTOCOL.StartupAllAPs() as Procedure.
+
+  @param[in] Buffer  Pointer to an MTRR_SETTINGS object, to be passed to
+                     MtrrSetAllMtrrs().
+**/
+VOID
+EFIAPI
+SetMtrrsFromBuffer (
+  IN VOID *Buffer
+  );
+
 #endif // _CPU_MP_H_