Re: [PATCH v16 04/99] qtest/arm-cpu-features: Use generic qtest_has_accel() to check for KVM

[Philippe Mathieu-Daudé]

On 6/8/21 10:22 AM, Philippe Mathieu-Daudé wrote:
> On 6/7/21 3:22 PM, Thomas Huth wrote:
>> On 04/06/2021 17.51, Alex Bennée wrote:
>>> From: Philippe Mathieu-Daudé <philmd@redhat.com>
>>>
>>> Use the recently added generic qtest_has_accel() method to
>>> check if KVM is available.
>>>
>>> Suggested-by: Claudio Fontana <cfontana@suse.de>
>>> Reviewed-by: Andrew Jones <drjones@redhat.com>
>>> Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
>>> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
>>> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
>>> Message-Id: <20210505125806.1263441-5-philmd@redhat.com>
>>> ---
>>>   tests/qtest/arm-cpu-features.c | 25 +------------------------
>>>   1 file changed, 1 insertion(+), 24 deletions(-)
>>>
>>> diff --git a/tests/qtest/arm-cpu-features.c
>>> b/tests/qtest/arm-cpu-features.c
>>> index 8252b85bb8..7f4b252127 100644
>>> --- a/tests/qtest/arm-cpu-features.c
>>> +++ b/tests/qtest/arm-cpu-features.c
>>> @@ -26,21 +26,6 @@
>>>                       "  'arguments': { 'type': 'full', "
>>>   #define QUERY_TAIL  "}}"
>>>   -static bool kvm_enabled(QTestState *qts)
>>> -{
>>> -    QDict *resp, *qdict;
>>> -    bool enabled;
>>> -
>>> -    resp = qtest_qmp(qts, "{ 'execute': 'query-kvm' }");
>>> -    g_assert(qdict_haskey(resp, "return"));
>>> -    qdict = qdict_get_qdict(resp, "return");
>>> -    g_assert(qdict_haskey(qdict, "enabled"));
>>> -    enabled = qdict_get_bool(qdict, "enabled");
>>> -    qobject_unref(resp);
>>> -
>>> -    return enabled;
>>> -}
>>> -
>>>   static QDict *do_query_no_props(QTestState *qts, const char *cpu_type)
>>>   {
>>>       return qtest_qmp(qts, QUERY_HEAD "'model': { 'name': %s }"
>>> @@ -493,14 +478,6 @@ static void
>>> test_query_cpu_model_expansion_kvm(const void *data)
>>>         qts = qtest_init(MACHINE_KVM "-cpu max");
>>>   -    /*
>>> -     * These tests target the 'host' CPU type, so KVM must be enabled.
>>> -     */
>>> -    if (!kvm_enabled(qts)) {
>>> -        qtest_quit(qts);
>>> -        return;
>>> -    }
>>> -
>>>       /* Enabling and disabling kvm-no-adjvtime should always work. */
>>>       assert_has_feature_disabled(qts, "host", "kvm-no-adjvtime");
>>>       assert_set_feature(qts, "host", "kvm-no-adjvtime", true);
>>> @@ -624,7 +601,7 @@ int main(int argc, char **argv)
>>>        * order avoid attempting to run an AArch32 QEMU with KVM on
>>>        * AArch64 hosts. That won't work and isn't easy to detect.
>>>        */
>>> -    if (g_str_equal(qtest_get_arch(), "aarch64")) {
>>> +    if (g_str_equal(qtest_get_arch(), "aarch64") &&
>>> qtest_has_accel("kvm")) {
>>>           qtest_add_data_func("/arm/kvm/query-cpu-model-expansion",
>>>                               NULL, test_query_cpu_model_expansion_kvm);
>>
>> I think this is wrong: query-kvm checks whether kvm is *enabled*, while
>> your new function only checks whether kvm has been built into the
>> binary. There is still the possibility that kvm has been built into the
>> binary, but is not available on the host, so in that case the test will
>> fail now.

Not enough coffee earlier. I think this is a documentation problem,
query-kvm returns a list of *runtime* accelerators:
https://www.mail-archive.com/qemu-devel@nongnu.org/msg811144.html

IIUC what Paolo said, if something asks for an accelerator that
is not present at build-time, then this is a configuration problem,
not relevant for the management interface.

>>
>> Thus please drop / rework this patch.
> 
> Indeed, this is unfortunate :(
>