Re: [PATCH] tests/functional: Convert the kvm_xen_guest avocado test

[David Woodhouse]

On 18 December 2024 18:16:13 CET, Thomas Huth <thuth@redhat.com> wrote:
>On 18/12/2024 17.19, Thomas Huth wrote:
>> On 18/12/2024 15.11, David Woodhouse wrote:
>>> On Wed, 2024-12-18 at 14:38 +0100, Thomas Huth wrote:
>> ...
>>>> But FWIW, there seems to be another issue with this test. While running it
>>>> multiple times, I sometimes see test_kvm_xen_guest_novector_noapic hanging.
>>>> According to the console output, the guest waits in vain for a device:
>>>> 
>>>> 2024-12-18 14:32:58,606: Initializing XFRM netlink socket
>>>> 2024-12-18 14:32:58,607: NET: Registered PF_INET6 protocol family
>>>> 2024-12-18 14:32:58,609: Segment Routing with IPv6
>>>> 2024-12-18 14:32:58,609: In-situ OAM (IOAM) with IPv6
>>>> 2024-12-18 14:32:58,610: NET: Registered PF_PACKET protocol family
>>>> 2024-12-18 14:32:58,610: 8021q: 802.1Q VLAN Support v1.8
>>>> 2024-12-18 14:32:58,611: 9pnet: Installing 9P2000 support
>>>> 2024-12-18 14:32:58,613: NET: Registered PF_VSOCK protocol family
>>>> 2024-12-18 14:32:58,614: IPI shorthand broadcast: enabled
>>>> 2024-12-18 14:32:58,619: sched_clock: Marking stable (551147059, 
>>>> -6778955)->(590359530, -45991426)
>>>> 2024-12-18 14:32:59,507: tsc: Refined TSC clocksource calibration: 
>>>> 2495.952 MHz
>>>> 2024-12-18 14:32:59,508: clocksource: tsc: mask: 0xffffffffffffffff 
>>>> max_cycles: 0x23fa49fc138, max_idle_ns: 440795295059 ns
>>>> 2024-12-18 14:32:59,509: clocksource: Switched to clocksource tsc
>>>> 2024-12-18 14:33:28,667: xenbus_probe_frontend: Waiting for devices to 
>>>> initialise: 25s...20s...15s...10s...5s...0s...
>>>> 
>>>> Have you seen this problem before?
>>> 
>>> That seems like event channel interrupts aren't being routed to the
>>> legacy i8259 PIC. I've certainly seen that kind of thing before,
>>> especially when asserted level-triggered interrupts weren't correctly
>>> being asserted. But I don't expect that of QEMU. I'll see if I can
>>> reproduce; thanks.
>>> 
>>> How often does it happen?
>> 
>> With the new functional test, it happens maybe 2 times out of 100 test runs.
>> 
>> I wasn't able to reproduce it with the avocado version yet, but that also 
>> runs 10x slower, so it takes a longer time to get to that many runs...
>
>Ok, FWIW, I've now also seen the problem with the old avocado version of the 
>test, so it's nothing that has been introduced by my patch. I just had to 
>downgrade to Avocado v88 again since the current version v103 does not seem to 
>correctly output the console anymore :-/ (which is another good indicator that 
>we really need to get the stuff moved over to the functional framework now).
>
> Thomas
>

I have reproduced it, will look into it. I'm fairly sure this was all working 
reliably at the time the Xen support was merged; that's why I wrote these test 
cases after all.