Messages in this thread | | | From | Alexey Zaytsev <> | Date | Tue, 20 Dec 2011 10:43:00 +0200 | Subject | Re: [Regression, bisected] a3e06bbe8445f57eb949e6474c5a9b30f24d2057: KVM: emulate lapic tsc deadline timer for guest" |
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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. >
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