OvmfPkg/CpuHotplugSmm: introduce First SMI Handler for hot-added CPUs

Implement the First SMI Handler for hot-added CPUs, in NASM.

Add the interfacing C-language function that the SMM Monarch calls. This
function launches and coordinates SMBASE relocation for a hot-added CPU.

Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Michael Kinney <michael.d.kinney@intel.com>
Cc: Philippe Mathieu-Daudé <philmd@redhat.com>
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=1512
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Message-Id: <20200226221156.29589-13-lersek@redhat.com>
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Tested-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>

OvmfPkg/CpuHotplugSmm/Smbase.h

@@ -12,6 +12,8 @@
 #include <Uefi/UefiBaseType.h> // EFI_STATUS
 #include <Uefi/UefiSpec.h>     // EFI_BOOT_SERVICES
 
+#include "ApicId.h"            // APIC_ID
+
 EFI_STATUS
 SmbaseAllocatePostSmmPen (
   OUT UINT32                  *PenAddress,
@@ -29,4 +31,16 @@ SmbaseReleasePostSmmPen (
   IN CONST EFI_BOOT_SERVICES *BootServices
   );
 
+VOID
+SmbaseInstallFirstSmiHandler (
+  VOID
+  );
+
+EFI_STATUS
+SmbaseRelocate (
+  IN APIC_ID ApicId,
+  IN UINTN   Smbase,
+  IN UINT32  PenAddress
+  );
+
 #endif // SMBASE_H_