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SubjectRE: [Regression, bisected] a3e06bbe8445f57eb949e6474c5a9b30f24d2057: KVM: emulate lapic tsc deadline timer for guest"
Alexey Zaytsev wrote:
> On Wed, Dec 14, 2011 at 11:37, Alexey Zaytsev
> <alexey.zaytsev@nexenta.com> wrote:
>> On Mon, Dec 12, 2011 at 10:13, Liu, Jinsong <jinsong.liu@intel.com>
>> wrote:
>>> Alexey Zaytsev wrote:
>>>> Hi.
>>>>
>>>> After a recent change, qemu --enable-kvm (both 0.15.92 and 1.0)
>>>> fails to boot illumos. The OS gets stuck pretty late in the boot
>>>> process, without any hints from the guest. MDB (the illumos
>>>> kenrnel debugger) failed to clarify the situation at once, the
>>>> kernel seems to be stuck idling. I've bisected the problem to
>>>> commit a3e06bbe8445f57eb949e6474c5a9b30f24d2057. Please let me
>>>> know if you need me to collect any debug information or test any
>>>> patches.
>>>
>>> Alexey,
>>>
>>> Does illumos use tsc deadline timer? and do you run it at Intel
>>> platform?
>>>
>>> If yes, would you please help me to collect debug information by
>>> add some printk points at kvm tsc deadline timer logic? currently I
>>> totally have no clue to figure out what the issue root from :) and,
>>> would you please check illumos tsc deadline timer logic by confirm
>>> whether illumos 1). Enumerate tsc deadline timer capability by
>>> CPUID; 2). Enable tsc deadline timer mode by lapic MMIO; 3). Start
>>> tsc deadline timer by WRMSR;
>>
>> I think, here's what's going on. We get into
>> kvm_get_lapic_tscdeadline_msr/kvm_set_lapic_tscdeadline_msr, but qemu
>> does not use the KVM_CREATE_IRQCHIP ioctl, so we are running without
>> vcpu->arch.apic and the functions do nothing. And the Linux guest
>> just handles broken tsc a lot  better, so it survives. Both guests
>> seem to work fine with qemu-kvm, which uses the ioctl.
>>
>
> Hi. Do you need any more info on thins?

Seems illumos works fine w/ qemu-kvm, that's enough. Maybe you need to wait qemu-kvm sync into qemu?

Thanks,
Jinsong--
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