Re: [Xen-devel] [xen-unstable test] 57852: regressions - FAIL

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 08.06.15 at 14:16, <ian.campbell@xxxxxxxxxx> wrote:
> On Mon, 2015-06-08 at 10:27 +0100, Ian Campbell wrote:
>> On Mon, 2015-06-08 at 10:15 +0100, Jan Beulich wrote:
>> > >>> On 08.06.15 at 10:53, <ian.campbell@xxxxxxxxxx> wrote:
>> > > That's 6/14 (43%) failure rate on fiano0 and 2/10 (20%) on fiano1. Which
>> > > differs form the apparent xen-unstable failure rate. But I wouldn't take
>> > > this as evidence that the two systems differ significantly, despite how
>> > > the unstable results looked at first glance.
>> > 
>> > So we can basically rule out just one of the hosts being the culprit;
>> > it's either both or our software. Considering that (again at the
>> > example of the recent 4.2 flight) the guest is apparently waiting for
>> > a timer (or other) interrupt (on a HLT instruction), this is very likely
>> > interrupt delivery related, yet (as said before, albeit wrongly for
>> > 4.3) 4.2 doesn't have APICV support yet (4.3 only lack the option
>> > to disable it), so it can't be that (alone).
>> > 
>> > Looking at the hardware - are fiano[01], in terms of CPU and
>> > chipset, perhaps the newest or oldest in the pool? (I'm trying to
>> > make myself a picture of what debugging options we have.)
>> 
>> I don't know much about the hardware in the pool other than what can be
>> gathered from the serial and dmesg logs.
>> 
>> 
> http://logs.test-lab.xenproject.org/osstest/logs/58028/test-amd64-amd64-xl-qe 
> muu-win7-amd64/info.html
>> 
>> From the serial log and this:
>> 
>> Jun  6 12:09:27.089020 (XEN) VMX: Supported advanced features:
>> Jun  6 12:09:27.089052 (XEN)  - APIC MMIO access virtualisation
>> Jun  6 12:09:27.097051 (XEN)  - APIC TPR shadow
>> Jun  6 12:09:27.097088 (XEN)  - Extended Page Tables (EPT)
>> Jun  6 12:09:27.097118 (XEN)  - Virtual-Processor Identifiers (VPID)
>> Jun  6 12:09:27.105066 (XEN)  - Virtual NMI
>> Jun  6 12:09:27.105100 (XEN)  - MSR direct-access bitmap
>> Jun  6 12:09:27.105130 (XEN)  - Unrestricted Guest
> 
> Running with no-apicv seems to have disabled these three:
> 
>> Jun  6 12:09:27.113269 (XEN)  - APIC Register Virtualization
>> Jun  6 12:09:27.113290 (XEN)  - Virtual Interrupt Delivery
>> Jun  6 12:09:27.113328 (XEN)  - Posted Interrupt Processing
> 
> Is that expected?

I think so, based on

        if ( (_vmx_cpu_based_exec_control & CPU_BASED_TPR_SHADOW) &&
             opt_apicv_enabled )
            opt |= SECONDARY_EXEC_APIC_REGISTER_VIRT |
                   SECONDARY_EXEC_VIRTUAL_INTR_DELIVERY |
                   SECONDARY_EXEC_VIRTUALIZE_X2APIC_MODE;

and

    if ( !(_vmx_secondary_exec_control & SECONDARY_EXEC_VIRTUAL_INTR_DELIVERY)
          || !(_vmx_vmexit_control & VM_EXIT_ACK_INTR_ON_EXIT) )
        _vmx_pin_based_exec_control  &= ~ PIN_BASED_POSTED_INTERRUPT;

Jan


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