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    SubjectRe: [Regression, bisected] a3e06bbe8445f57eb949e6474c5a9b30f24d2057: KVM: emulate lapic tsc deadline timer for guest"
    On Tue, Dec 20, 2011 at 10:53, Liu, Jinsong <jinsong.liu@intel.com> wrote:
    > 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?
    >

    Qemu-kvm is fine for me, but this is a regression and should be fixed.
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