xemu/python/qemu/accel.py
John Snow f12a282ff4 python/qemu: Add mypy type annotations
These should all be purely annotations with no changes in behavior at
all. You need to be in the python folder, but you should be able to
confirm that these annotations are correct (or at least self-consistent)
by running `mypy --strict qemu`.

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Message-id: 20201006235817.3280413-12-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>
2020-10-20 09:37:57 -04:00

85 lines
2.3 KiB
Python

"""
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)