qemu-img: add support for rate limit in qemu-img commit
[qemu.git] / python / qemu / accel.py
1 """
2 QEMU accel module:
3
4 This module provides utilities for discover and check the availability of
5 accelerators.
6 """
7 # Copyright (C) 2015-2016 Red Hat Inc.
8 # Copyright (C) 2012 IBM Corp.
9 #
10 # Authors:
11 # Fam Zheng <famz@redhat.com>
12 #
13 # This work is licensed under the terms of the GNU GPL, version 2. See
14 # the COPYING file in the top-level directory.
15 #
16
17 import logging
18 import os
19 import subprocess
20 from typing import List, Optional
21
22
23 LOG = logging.getLogger(__name__)
24
25 # Mapping host architecture to any additional architectures it can
26 # support which often includes its 32 bit cousin.
27 ADDITIONAL_ARCHES = {
28 "x86_64": "i386",
29 "aarch64": "armhf",
30 "ppc64le": "ppc64",
31 }
32
33
34 def list_accel(qemu_bin: str) -> List[str]:
35 """
36 List accelerators enabled in the QEMU binary.
37
38 @param qemu_bin (str): path to the QEMU binary.
39 @raise Exception: if failed to run `qemu -accel help`
40 @return a list of accelerator names.
41 """
42 if not qemu_bin:
43 return []
44 try:
45 out = subprocess.check_output([qemu_bin, '-accel', 'help'],
46 universal_newlines=True)
47 except:
48 LOG.debug("Failed to get the list of accelerators in %s", qemu_bin)
49 raise
50 # Skip the first line which is the header.
51 return [acc.strip() for acc in out.splitlines()[1:]]
52
53
54 def kvm_available(target_arch: Optional[str] = None,
55 qemu_bin: Optional[str] = None) -> bool:
56 """
57 Check if KVM is available using the following heuristic:
58 - Kernel module is present in the host;
59 - Target and host arches don't mismatch;
60 - KVM is enabled in the QEMU binary.
61
62 @param target_arch (str): target architecture
63 @param qemu_bin (str): path to the QEMU binary
64 @return True if kvm is available, otherwise False.
65 """
66 if not os.access("/dev/kvm", os.R_OK | os.W_OK):
67 return False
68 if target_arch:
69 host_arch = os.uname()[4]
70 if target_arch != host_arch:
71 if target_arch != ADDITIONAL_ARCHES.get(host_arch):
72 return False
73 if qemu_bin and "kvm" not in list_accel(qemu_bin):
74 return False
75 return True
76
77
78 def tcg_available(qemu_bin: str) -> bool:
79 """
80 Check if TCG is available.
81
82 @param qemu_bin (str): path to the QEMU binary
83 """
84 return 'tcg' in list_accel(qemu_bin)