OvmfPkg: introduce -D SMM_REQUIRE and PcdSmmSmramRequire

This build time flag and corresponding Feature PCD will control whether
OVMF supports (and, equivalently, requires) SMM/SMRAM support from QEMU.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>

git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@19034 6f19259b-4bc3-4df7-8a09-765794883524

OvmfPkg/OvmfPkgX64.dsc

@@ -36,6 +36,7 @@
   DEFINE SECURE_BOOT_ENABLE      = FALSE
   DEFINE NETWORK_IP6_ENABLE      = FALSE
   DEFINE HTTP_BOOT_ENABLE        = FALSE
+  DEFINE SMM_REQUIRE             = FALSE
 
 [BuildOptions]
   GCC:*_UNIXGCC_*_CC_FLAGS             = -DMDEPKG_NDEBUG
@@ -315,6 +316,9 @@
 !if $(SECURE_BOOT_ENABLE) == TRUE
   gUefiOvmfPkgTokenSpaceGuid.PcdSecureBootEnable|TRUE
 !endif
+!if $(SMM_REQUIRE) == TRUE
+  gUefiOvmfPkgTokenSpaceGuid.PcdSmmSmramRequire|TRUE
+!endif
 
 [PcdsFixedAtBuild]
   gEfiMdeModulePkgTokenSpaceGuid.PcdStatusCodeMemorySize|1