cachepc-qemu

Fork of AMDESE/qemu with changes for cachepc side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-qemu
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accel.py (2348B)

      1"""
      2QEMU accel module:
      3
      4This module provides utilities for discover and check the availability of
      5accelerators.
      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
     17import logging
     18import os
     19import subprocess
     20from typing import List, Optional
     21
     22
     23LOG = logging.getLogger(__name__)
     24
     25# Mapping host architecture to any additional architectures it can
     26# support which often includes its 32 bit cousin.
     27ADDITIONAL_ARCHES = {
     28    "x86_64": "i386",
     29    "aarch64": "armhf",
     30    "ppc64le": "ppc64",
     31}
     32
     33
     34def 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
     54def 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
     78def 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)