Re: [PATCH v8 9/9] qtest/hyperv: Introduce a simple hyper-v test

[Vitaly Kuznetsov <vkuznets@redhat.com>]

Igor Mammedov <imammedo@redhat.com> writes:

> On Thu, 8 Jul 2021 17:02:22 -0400
> Eduardo Habkost <ehabkost@redhat.com> wrote:
>
>> On Tue, Jun 08, 2021 at 02:08:17PM +0200, Vitaly Kuznetsov wrote:
>> > For the beginning, just test 'hv-passthrough' and a couple of custom
>> > Hyper-V  enlightenments configurations through QMP. Later, it would
>> > be great to complement this by checking CPUID values from within the
>> > guest.
>> > 
>> > Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>  
>> [...]
>> > +static bool kvm_has_sys_hyperv_cpuid(void)
>> > +{
>> > +    int fd = open("/dev/kvm", O_RDWR);
>> > +    int ret;
>> > +
>> > +    g_assert(fd > 0);  
>> 

g_assert() was an overkill, just 'return false' would do.

>> This crashes when /dev/kvm doesn't exist.  See:
>> https://gitlab.com/ehabkost/qemu/-/jobs/1404084459
>
> maybe reuse qtest_has_accel()
>  https://lists.gnu.org/archive/html/qemu-devel/2021-06/msg06864.html
>
> instead of op encoding it.

The purpose of this function is to check if KVM_CAP_SYS_HYPERV_CPUID is
supported by KVM. It is certainly unsupported when KVM is not present
:-) but an ioctl() is needed when it is.

We already have a similar check in tests/qtest/migration-test.c where we
test for KVM_CAP_DIRTY_LOG_RING, maybe we can create a library function
but we don't seem to have any KVM-specific stuff in qtest at this moment
...

>> I'm removing it from the queue.

I'll fix g_assert() and send as a separate patch if it's fine.

-- 
Vitaly