Re: [PATCH v2 3/4] python/qemu: accel: Strengthen kvm_available() checks

[Cleber Rosa <crosa@redhat.com>]

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On Fri, Dec 06, 2019 at 04:34:32PM -0500, Wainer dos Santos Moschetta wrote:
> Currently kvm_available() checks for the presence of kvm module
> and, if target and host arches don't mismatch. This patch adds
> an 3rd checking: if QEMU binary was compiled with kvm
> support.
> 
> Signed-off-by: Wainer dos Santos Moschetta <wainersm@redhat.com>
> Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
> Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> ---
>  python/qemu/accel.py | 27 +++++++++++++++++++++------
>  1 file changed, 21 insertions(+), 6 deletions(-)
> 
> diff --git a/python/qemu/accel.py b/python/qemu/accel.py
> index 746b7e68f5..9fecffb44b 100644
> --- a/python/qemu/accel.py
> +++ b/python/qemu/accel.py
> @@ -46,9 +46,24 @@ def list_accel(qemu_bin):
>      # Skip the first line which is the header.
>      return [l.strip() for l in lines[1:] if l]
>  
> -def kvm_available(target_arch=None):
> -    host_arch = os.uname()[4]
> -    if target_arch and target_arch != host_arch:
> -        if target_arch != ADDITIONAL_ARCHES.get(host_arch):
> -            return False
> -    return os.access("/dev/kvm", os.R_OK | os.W_OK)
> +def kvm_available(target_arch=None, qemu_bin=None):
> +    """
> +    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
> -- 
> 2.21.0
> 

Reviewed-by: Cleber Rosa <crosa@redhat.com>
Tested-by: Cleber Rosa <crosa@redhat.com>

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