perf tools: Add machine to machines back pointer

When dealing with guest machines, it can be necessary to get a reference
to the host machine. Add a machines pointer to struct machine to make that
possible.
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: kvm@vger.kernel.org
Link: https://lore.kernel.org/r/20220517131011.6117-2-adrian.hunter@intel.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/machine.c

@@ -299,6 +299,8 @@ struct machine *machines__add(struct machines *machines, pid_t pid,
 	rb_link_node(&machine->rb_node, parent, p);
 	rb_insert_color_cached(&machine->rb_node, &machines->guests, leftmost);
 
+	machine->machines = machines;
+
 	return machine;
 }
 

tools/perf/util/machine.h

@@ -18,6 +18,7 @@ struct symbol;
 struct target;
 struct thread;
 union perf_event;
+struct machines;
 
 /* Native host kernel uses -1 as pid index in machine */
 #define	HOST_KERNEL_ID			(-1)
@@ -59,6 +60,7 @@ struct machine {
 		void	  *priv;
 		u64	  db_id;
 	};
+	struct machines   *machines;
 	bool		  trampolines_mapped;
 };