1 files changed, 98 insertions, 3 deletions

diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index 95391236f5f6..009061852808 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -84,6 +84,14 @@ static int machine__set_mmap_name(struct machine *machine)
 	return machine->mmap_name ? 0 : -ENOMEM;
 }
 
+static void thread__set_guest_comm(struct thread *thread, pid_t pid)
+{
+	char comm[64];
+
+	snprintf(comm, sizeof(comm), "[guest/%d]", pid);
+	thread__set_comm(thread, comm, 0);
+}
+
 int machine__init(struct machine *machine, const char *root_dir, pid_t pid)
 {
 	int err = -ENOMEM;
@@ -119,13 +127,11 @@ int machine__init(struct machine *machine, const char *root_dir, pid_t pid)
 	if (pid != HOST_KERNEL_ID) {
 		struct thread *thread = machine__findnew_thread(machine, -1,
 								pid);
-		char comm[64];
 
 		if (thread == NULL)
 			goto out;
 
-		snprintf(comm, sizeof(comm), "[guest/%d]", pid);
-		thread__set_comm(thread, comm, 0);
+		thread__set_guest_comm(thread, pid);
 		thread__put(thread);
 	}
 
@@ -299,6 +305,8 @@ 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;
 }
 
@@ -384,6 +392,93 @@ struct machine *machines__find_guest(struct machines *machines, pid_t pid)
 	return machine;
 }
 
+/*
+ * A common case for KVM test programs is that the test program acts as the
+ * hypervisor, creating, running and destroying the virtual machine, and
+ * providing the guest object code from its own object code. In this case,
+ * the VM is not running an OS, but only the functions loaded into it by the
+ * hypervisor test program, and conveniently, loaded at the same virtual
+ * addresses.
+ *
+ * Normally to resolve addresses, MMAP events are needed to map addresses
+ * back to the object code and debug symbols for that object code.
+ *
+ * Currently, there is no way to get such mapping information from guests
+ * but, in the scenario described above, the guest has the same mappings
+ * as the hypervisor, so support for that scenario can be achieved.
+ *
+ * To support that, copy the host thread's maps to the guest thread's maps.
+ * Note, we do not discover the guest until we encounter a guest event,
+ * which works well because it is not until then that we know that the host
+ * thread's maps have been set up.
+ *
+ * This function returns the guest thread. Apart from keeping the data
+ * structures sane, using a thread belonging to the guest machine, instead
+ * of the host thread, allows it to have its own comm (refer
+ * thread__set_guest_comm()).
+ */
+static struct thread *findnew_guest_code(struct machine *machine,
+					 struct machine *host_machine,
+					 pid_t pid)
+{
+	struct thread *host_thread;
+	struct thread *thread;
+	int err;
+
+	if (!machine)
+		return NULL;
+
+	thread = machine__findnew_thread(machine, -1, pid);
+	if (!thread)
+		return NULL;
+
+	/* Assume maps are set up if there are any */
+	if (thread->maps->nr_maps)
+		return thread;
+
+	host_thread = machine__find_thread(host_machine, -1, pid);
+	if (!host_thread)
+		goto out_err;
+
+	thread__set_guest_comm(thread, pid);
+
+	/*
+	 * Guest code can be found in hypervisor process at the same address
+	 * so copy host maps.
+	 */
+	err = maps__clone(thread, host_thread->maps);
+	thread__put(host_thread);
+	if (err)
+		goto out_err;
+
+	return thread;
+
+out_err:
+	thread__zput(thread);
+	return NULL;
+}
+
+struct thread *machines__findnew_guest_code(struct machines *machines, pid_t pid)
+{
+	struct machine *host_machine = machines__find(machines, HOST_KERNEL_ID);
+	struct machine *machine = machines__findnew(machines, pid);
+
+	return findnew_guest_code(machine, host_machine, pid);
+}
+
+struct thread *machine__findnew_guest_code(struct machine *machine, pid_t pid)
+{
+	struct machines *machines = machine->machines;
+	struct machine *host_machine;
+
+	if (!machines)
+		return NULL;
+
+	host_machine = machines__find(machines, HOST_KERNEL_ID);
+
+	return findnew_guest_code(machine, host_machine, pid);
+}
+
 void machines__process_guests(struct machines *machines,
 			      machine__process_t process, void *data)
 {