Re: [PATCH v8 08/11] tests/qtest: Fix tests when no KVM or TCG are present

[Fabiano Rosas]

Thomas Huth <thuth@redhat.com> writes:

> On 10/03/2023 14.06, Fabiano Rosas wrote:
>> "Michael S. Tsirkin" <mst@redhat.com> writes:
>> 
>>> On Thu, Mar 09, 2023 at 05:14:31PM -0300, Fabiano Rosas wrote:
>>>> It is possible to have a build with both TCG and KVM disabled due to
>>>> Xen requiring the i386 and x86_64 binaries to be present in an aarch64
>>>> host.
>>>>
>>>> If we build with --disable-tcg on the aarch64 host, we will end-up
>>>> with a QEMU binary (x86) that does not support TCG nor KVM.
>>>>
>>>> Fix tests that crash or hang in the above scenario. Do not include any
>>>> test cases if TCG and KVM are missing.
>>>>
>>>> Make sure that calls to qtest_has_accel are placed after g_test_init
>>>> in similar fashion to commit ae4b01b349 ("tests: Ensure TAP version is
>>>> printed before other messages") to avoid TAP parsing errors.
>>>>
>>>> Signed-off-by: Fabiano Rosas <farosas@suse.de>
>>>> Reviewed-by: Juan Quintela <quintela@redhat.com>
>>>
>>> I don't like it that we are hard-coding the list of accelerators
>>> like this. Make a wrapper?
>>>
>> 
>> Are you thinking of some sort of "has_any_accel" wrapper?
>
> I think in the long run, we want something like what I described here:
>
> https://lore.kernel.org/qemu-devel/ee0cad00-a6f3-f0c1-adf0-ba32329354f3@redhat.com/
>

Wont't that function be too generic? The choice of accelerator is quite
specific to each individual test, some might not work with TCG, some
might not work with HVF and so on. There is no link between build-time
configuration and runtime test execution after all. We could always have
a build without an accelerator and then try to run a test that uses that
accelerator. And also have an accelerator present that the test does not
support at all.


For this particularly bizarre case of not having TCG nor KVM in the
build I'm inclined to go with Michael's suggestion of checking it at
build time and skipping all the hassle. This is what I'm preparing:

diff --git a/tests/qtest/meson.build b/tests/qtest/meson.build
index 29a4efb4c2..e698cdcb60 100644
--- a/tests/qtest/meson.build
+++ b/tests/qtest/meson.build
@@ -27,6 +27,12 @@ if config_host.has_key('CONFIG_MODULES')
   qtests_generic += [ 'modules-test' ]
 endif
 
+# For x86_64, i386 and aarch64 it is possible to have only Xen as an
+# accelerator. Some tests require either TCG or KVM, so make sure they
+# are present before building those tests.
+tcg_or_kvm_available = (config_all.has_key('CONFIG_TCG') or
+                        config_all.has_key('CONFIG_KVM'))
+
 qtests_pci = \
   (config_all_devices.has_key('CONFIG_VGA') ? ['display-vga-test'] : []) +     
             \
   (config_all_devices.has_key('CONFIG_IVSHMEM_DEVICE') ? ['ivshmem-test'] : [])
@@ -40,11 +46,12 @@ qtests_filter = \
   (config_host.has_key('CONFIG_POSIX') ? ['test-filter-redirector'] : [])
 
 qtests_i386 = \
-  (slirp.found() ? ['pxe-test'] : []) + \
+  (slirp.found() and tcg_or_kvm_available ? ['pxe-test'] : []) +               
             \
---

What do you think?