python: create qemu packages

move python/qemu/*.py to python/qemu/[machine, qmp, utils]/*.py and
update import directives across the tree.

This is done to create a PEP420 namespace package, in which we may
create subpackages. To do this, the namespace directory ("qemu") should
not have any modules in it. Those files will go into new 'machine',
'qmp' and 'utils' subpackages instead.

Implement machine/__init__.py making the top-level classes and functions
from its various modules available directly inside the package. Change
qmp.py to qmp/__init__.py similarly, such that all of the useful QMP
library classes are available directly from "qemu.qmp" instead of
"qemu.qmp.qmp".

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Cleber Rosa <crosa@redhat.com>
Message-id: 20210527211715.394144-10-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>

1 files changed, 84 insertions, 0 deletions

diff --git a/python/qemu/utils/accel.py b/python/qemu/utils/accel.py
new file mode 100644
index 0000000000..297933df2a
--- /dev/null
+++ b/python/qemu/utils/accel.py
@@ -0,0 +1,84 @@
+"""
+QEMU accel module:
+
+This module provides utilities for discover and check the availability of
+accelerators.
+"""
+# Copyright (C) 2015-2016 Red Hat Inc.
+# Copyright (C) 2012 IBM Corp.
+#
+# Authors:
+#  Fam Zheng <famz@redhat.com>
+#
+# This work is licensed under the terms of the GNU GPL, version 2.  See
+# the COPYING file in the top-level directory.
+#
+
+import logging
+import os
+import subprocess
+from typing import List, Optional
+
+
+LOG = logging.getLogger(__name__)
+
+# Mapping host architecture to any additional architectures it can
+# support which often includes its 32 bit cousin.
+ADDITIONAL_ARCHES = {
+    "x86_64": "i386",
+    "aarch64": "armhf",
+    "ppc64le": "ppc64",
+}
+
+
+def list_accel(qemu_bin: str) -> List[str]:
+    """
+    List accelerators enabled in the QEMU binary.
+
+    @param qemu_bin (str): path to the QEMU binary.
+    @raise Exception: if failed to run `qemu -accel help`
+    @return a list of accelerator names.
+    """
+    if not qemu_bin:
+        return []
+    try:
+        out = subprocess.check_output([qemu_bin, '-accel', 'help'],
+                                      universal_newlines=True)
+    except:
+        LOG.debug("Failed to get the list of accelerators in %s", qemu_bin)
+        raise
+    # Skip the first line which is the header.
+    return [acc.strip() for acc in out.splitlines()[1:]]
+
+
+def kvm_available(target_arch: Optional[str] = None,
+                  qemu_bin: Optional[str] = None) -> bool:
+    """
+    Check if KVM is available using the following heuristic:
+      - Kernel module is present in the host;
+      - Target and host arches don't mismatch;
+      - KVM is enabled in the QEMU binary.
+
+    @param target_arch (str): target architecture
+    @param qemu_bin (str): path to the QEMU binary
+    @return True if kvm is available, otherwise False.
+    """
+    if not os.access("/dev/kvm", os.R_OK | os.W_OK):
+        return False
+    if target_arch:
+        host_arch = os.uname()[4]
+        if target_arch != host_arch:
+            if target_arch != ADDITIONAL_ARCHES.get(host_arch):
+                return False
+    if qemu_bin and "kvm" not in list_accel(qemu_bin):
+        return False
+    return True
+
+
+def tcg_available(qemu_bin: str) -> bool:
+    """
+    Check if TCG is available.
+
+    @param qemu_bin (str): path to the QEMU binary
+    """
+    return 'tcg' in list_accel(qemu_bin)