Re: [xen-unstable test] 33690: regressions - FAIL

[Boris Ostrovsky <boris.ostrovsky@oracle.com>]

On 01/26/2015 09:49 AM, Andrew Cooper wrote:
> On 26/01/15 11:38, Jan Beulich wrote:
>>>>> On 26.01.15 at 12:04, <JBeulich@suse.com> wrote:
>>>>>> On 24.01.15 at 13:54, <Ian.Jackson@eu.citrix.com> wrote:
>>>>   test-amd64-amd64-xl-qemut-win7-amd64  7 windows-install   fail REGR. vs. 33637
>>> Jan 24 00:35:16.262627 (XEN) ----[ Xen-4.6-unstable  x86_64  debug=y  Not tainted ]----
>>> Jan 24 00:35:16.478599 (XEN) CPU:    1
>>> Jan 24 00:35:16.478624 (XEN) RIP:    e008:[<0000000000000000>] 0000000000000000
>>> Jan 24 00:35:16.486596 (XEN) RFLAGS: 0000000000010082   CONTEXT: hypervisor
>>> ...
>>> Jan 24 00:35:16.678620 (XEN) Xen call trace:
>>> Jan 24 00:35:16.678650 (XEN)    [<ffff82d0801d36d0>] vpmu_do_interrupt+0x2f/0x8a
>>> Jan 24 00:35:16.686605 (XEN)    [<ffff82d08015e242>] pmu_apic_interrupt+0x33/0x35
>>> Jan 24 00:35:16.698582 (XEN)    [<ffff82d080171bf0>] do_IRQ+0x9c/0x624
>>> Jan 24 00:35:16.698615 (XEN)    [<ffff82d080234062>] common_interrupt+0x62/0x70
>>> Jan 24 00:35:16.698653 (XEN)    [<ffff82d08012c6fe>] _spin_unlock_irq+0x30/0x31
>>> Jan 24 00:35:16.706604 (XEN)    [<ffff82d08012bcf1>] __do_softirq+0x81/0x8c
>>> Jan 24 00:35:16.706638 (XEN)    [<ffff82d08012bd49>] do_softirq+0x13/0x15
>>> Jan 24 00:35:16.718591 (XEN)    [<ffff82d0801ec4da>] vmx_asm_do_vmentry+0x2a/0x50
>> I think I see what the problem here is: Commit 8097616fbd
>> ("x86/VPMU: handle APIC_LVTPC accesses") gives the guest
>> control over LVTPC.mask regardless of whether the vPMU was
>> actually initialized for it. Supposedly in the case above the
>> guest is being run with core2_no_vpmu_ops, which in
>> particular has .do_interrupt == NULL. It's not immediately
>> clear whether vpmu_lvtpc_update() should do the check or its
>> (sole) caller. In any event I'm going to revert that commit as
>> the primary suspect for causing the regression.
> I have just fallen over this as well.  I second a revert in the absence
> of a clear way to fix the patch.

I can't reproduce this -- neither at this patch level nor at full series.

Yes, we can test for do_interrupt presence in vpmu_lvtpc_update() (or in 
vpmu_interrupt() itself) but since we cannot arm the counters (there is 
no do_wrmsr op) I am not sure I understand what can trigger this interrupt.

-boris