OvmfPkg/CpuHotplugSmm: add Qemu Cpu Status helper

Add QemuCpuhpWriteCpuStatus() which will be used to update the QEMU
CPU status register. On error, it hangs in a similar fashion as
other helper functions.

Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Ard Biesheuvel <ard.biesheuvel@arm.com>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Aaron Young <aaron.young@oracle.com>
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=3132
Signed-off-by: Ankur Arora <ankur.a.arora@oracle.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Message-Id: <20210312062656.2477515-4-ankur.a.arora@oracle.com>

OvmfPkg/CpuHotplugSmm/QemuCpuhp.c

@@ -113,6 +113,28 @@ QemuCpuhpWriteCpuSelector (
   }
 }
 
+VOID
+QemuCpuhpWriteCpuStatus (
+  IN CONST EFI_MM_CPU_IO_PROTOCOL *MmCpuIo,
+  IN UINT8                        CpuStatus
+  )
+{
+  EFI_STATUS Status;
+
+  Status = MmCpuIo->Io.Write (
+                         MmCpuIo,
+                         MM_IO_UINT8,
+                         ICH9_CPU_HOTPLUG_BASE + QEMU_CPUHP_R_CPU_STAT,
+                         1,
+                         &CpuStatus
+                         );
+  if (EFI_ERROR (Status)) {
+    DEBUG ((DEBUG_ERROR, "%a: %r\n", __FUNCTION__, Status));
+    ASSERT (FALSE);
+    CpuDeadLoop ();
+  }
+}
+
 VOID
 QemuCpuhpWriteCommand (
   IN CONST EFI_MM_CPU_IO_PROTOCOL *MmCpuIo,

OvmfPkg/CpuHotplugSmm/QemuCpuhp.h

@@ -41,6 +41,12 @@ QemuCpuhpWriteCpuSelector (
   IN UINT32                       Selector
   );
 
+VOID
+QemuCpuhpWriteCpuStatus (
+  IN CONST EFI_MM_CPU_IO_PROTOCOL *MmCpuIo,
+  IN UINT8                        CpuStatus
+  );
+
 VOID
 QemuCpuhpWriteCommand (
   IN CONST EFI_MM_CPU_IO_PROTOCOL *MmCpuIo,