linux-kernel - RE: [Regression, bisected] a3e06bbe8445f57eb949e6474c5a9b30f24d2057: KVM: emulate lapic tsc deadline timer for guest"

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <BC00F5384FCFC9499AF06F92E8B78A9E289048778E@shsmsx502.ccr.corp.intel.com>
Date:	Tue, 20 Dec 2011 16:53:56 +0800
From:	"Liu, Jinsong" <jinsong.liu@...el.com>
To:	Alexey Zaytsev <alexey.zaytsev@...il.com>
CC:	Kernel development list <linux-kernel@...r.kernel.org>,
	Jan Kiszka <jan.kiszka@...mens.com>,
	Marcelo Tosatti <mtosatti@...hat.com>,
	Avi Kivity <avi@...hat.com>,
	Garrett D'Amore <garrett@...enta.com>
Subject: RE: [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@...enta.com> wrote:
>> On Mon, Dec 12, 2011 at 10:13, Liu, Jinsong <jinsong.liu@...el.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--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/