Re: [RFC PATCH] tests/qemuxml2*/graphics-spice-timeout: skip CPU model check

On 11/17/21 07:51, Peter Krempa wrote: > On Tue, Nov 16, 2021 at 21:11:50 -0300, Daniel Henrique Barboza wrote: >> Commit 65b0b746b516 changed spice tests to use latest caps. Before this >> change, "FLAG_REAL_CAPS" wasn't being set in testQemuInfoInitArgs(). The >> absence of this flag triggered the code path inside >> testCompareXMLToArgv() that executed testUpdateQEMUCaps(). This function >> will update the host CPU via virQEMUCapsUpdateHostCPUModel() into >> virQEMUCapsInitHostCPUModel().  In this function, >> virQEMUCapsInitCPUModel() would end up updating the hostCPU inside the >> qemuCaps (via virQEMUCapsProbeHostCPU()). Before the forementioned >> commit, the host CPU was being defaulted to x86_64, vendor Intel, for >> the 'graphics-spice-timeout' test that is using the 'pc' machine type >> and 'accel=kvm'. >> >> Today, "FLAG_REAL_CAPS" is being set because we're using the latest caps >> from x86_64. This means that the whole code path mentioned above is >> skipped. qemuCaps are now being loaded via virQEMUCapsLoadCache() >> directly.  Without the handling being done by testUpdateQEMUCaps(), the >> host CPU is being retrieved later on, down below >> qemuProcessCreatePretendCmdPrepare() into qemuProcessUpdateGuestCPU(). >> The latter will attempt to update the domain cpu and executing a >> virCPUCompare with the hostCPU and def->cpu. >> >> All this logic ended up causing a failure of the >> 'graphics-spice-timeout' test in ppc64 and s390x hosts. This test is >> being run with KVM acceleration, and the KVM driver for ppc64 and s390x >> will return a default x86_64 CPU with vendor "AMD", making >> virCPUCompare() fail with the following message: > > With all of this description which sounds plausible and pointing to the > root cause of tests not being stable enough when used with real caps, > the fix you are proposing seems to really just fix the symptom. > > This patch itself is acceptable as is, but doesn't really fix the real > issue. If you don't plan on addressing the root cause, please: I'll wait to see if that fixes the problem Boris was experiencing with s390x. Meanwhile I'll dig further to see if I can detect the root cause of the problem (e.g. can we default to an Intel CPU instead of AMD).

> > 1) note in the commit message for this commit that it's not really >     fixing the root cause, just the symptom > > 2) file an upstream issue with your analysis so that we don't forget >     that this is still broken If I fail to fix the root cause in a sensible time I'll end up pushing this patch - with the adjustments you suggested - to not let the tests being broken for too long. I'll file the bug shortly. Thanks, Daniel > >> "QEMU XML-2-ARGV graphics-spice-timeout.x86_64-latest   ... libvirt: CPU >> Driver error : the CPU is incompatible with host CPU: host CPU vendor >> does >> not match required CPU vendor Intel" >> >> Fix this test by setting cpu check='none' and avoid the virCPUCompare() >> that causes the problem for ppc64 and s390x hosts. > > To resolve point 1), be more explicit that it's just a symptom fix in > this sentence. > >> >> Reported-by: Boris Fiuczynski <fiuczy(a)linux.ibm.com&gt; >> Signed-off-by: Daniel Henrique Barboza <danielhb413(a)gmail.com&gt; >> --- >> >> Sending as a RFC because I'm not sure if this patch fixes the >> problem for s390x. Boris, can you please test and see if this >> fix works for you? > > It is plausible it will work, there are other cases which use > match='exact' check='none' using real caps on X86 and they don't seem to > be causing problems. >