trace: Add 'vcpu' event property to trace guest vCPU

This property identifies events that trace vCPU-specific information.

It adds a "CPUState*" argument to events with the property, identifying
the vCPU raising the event. TCG translation events also have a
"TCGv_env" implicit argument that is later used as the "CPUState*"
argument at execution time.

Signed-off-by: Lluís Vilanova <vilanova@ac.upc.edu>
Message-id: 145641861797.30295.6991314023181842105.stgit@localhost
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

scripts/tracetool/vcpu.py

@@ -0,0 +1,70 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+"""
+Generic management for the 'vcpu' property.
+
+"""
+
+__author__     = "Lluís Vilanova <vilanova@ac.upc.edu>"
+__copyright__  = "Copyright 2016, Lluís Vilanova <vilanova@ac.upc.edu>"
+__license__    = "GPL version 2 or (at your option) any later version"
+
+__maintainer__ = "Stefan Hajnoczi"
+__email__      = "stefanha@linux.vnet.ibm.com"
+
+
+from tracetool import Arguments, try_import
+
+
+def transform_event(event):
+    """Transform event to comply with the 'vcpu' property (if present)."""
+    if "vcpu" in event.properties:
+        # events with 'tcg-trans' and 'tcg-exec' are auto-generated from
+        # already-patched events
+        assert "tcg-trans" not in event.properties
+        assert "tcg-exec" not in event.properties
+
+        event.args = Arguments([("CPUState *", "__cpu"), event.args])
+        if "tcg" in event.properties:
+            fmt = "\"cpu=%p \""
+            event.fmt = [fmt + event.fmt[0],
+                         fmt + event.fmt[1]]
+        else:
+            fmt = "\"cpu=%p \""
+            event.fmt = fmt + event.fmt
+    return event
+
+
+def transform_args(format, event, *args, **kwargs):
+    """Transforms the arguments to suit the specified format.
+
+    The format module must implement function 'vcpu_args', which receives the
+    implicit arguments added by the 'vcpu' property, and must return suitable
+    arguments for the given format.
+
+    The function is only called for events with the 'vcpu' property.
+
+    Parameters
+    ==========
+    format : str
+        Format module name.
+    event : Event
+    args, kwargs
+        Passed to 'vcpu_transform_args'.
+
+    Returns
+    =======
+    Arguments
+        The transformed arguments, including the non-implicit ones.
+
+    """
+    if "vcpu" in event.properties:
+        ok, func = try_import("tracetool.format." + format,
+                              "vcpu_transform_args")
+        assert ok
+        assert func
+        return Arguments([func(event.args[:1], *args, **kwargs),
+                          event.args[1:]])
+    else:
+        return event.args