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

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 26.01.15 at 12:04, <JBeulich@xxxxxxxx> wrote:
>>>> On 24.01.15 at 13:54, <Ian.Jackson@xxxxxxxxxxxxx> 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.

Jan


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