cpu: Add a sendFunctional function to the ThreadContext.

This can be used to send a functional packet from the perspective of a
thread context. Currently this will not consider targets within the CPU
like the local APIC on x86. The default implementation sends a packet
using the port on the way out of the CPU.

Change-Id: Idb311e156a416ad51b585794c1e9fa75711d61f1
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/45861
Maintainer: Gabe Black <gabe.black@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Yu-hsin Wang <yuhsingw@google.com>
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>

src/cpu/thread_context.cc

@@ -48,6 +48,7 @@
 #include "cpu/base.hh"
 #include "debug/Context.hh"
 #include "debug/Quiesce.hh"
+#include "mem/port.hh"
 #include "params/BaseCPU.hh"
 #include "sim/full_system.hh"
 
@@ -127,6 +128,15 @@ ThreadContext::compare(ThreadContext *one, ThreadContext *two)
 
 }
 
+void
+ThreadContext::sendFunctional(PacketPtr pkt)
+{
+    const auto *port =
+        dynamic_cast<const RequestPort *>(&getCpuPtr()->getDataPort());
+    assert(port);
+    port->sendFunctional(pkt);
+}
+
 void
 ThreadContext::quiesce()
 {