From: Avi Kivity <avi@qumranet.com>
To: bugme-daemon@bugzilla.kernel.org
Cc: Ingo Molnar <mingo@elte.hu>, linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [Bug 11219] KVM modules break emergency reboot
Date: Mon, 18 Aug 2008 16:39:38 +0300 [thread overview]
Message-ID: <48A97B9A.1040800@qumranet.com> (raw)
In-Reply-To: <20080812091950.61E3911D109@picon.linux-foundation.org>
(copying mingo)
(context: sysrq-B with kvm-intel.ko loaded doesn't work. on my machine,
it kills the sata interface, but the processor and network keeps working)
Strangely, the specs say:
> • The INIT signal is blocked whenever a logical processor is in VMX
> root operation.
> It is not blocked in VMX non-root operation. Instead, INITs cause VM
> exits (see
> Section 21.3, “Other Causes of VM Exits”).
So INIT (which is wired to the triple-fault processor output, it seems,
rather than RESET) is blocked and the machine is not reset completely.
So we need to disable vmx during native_machine_emergency_restart().
There are at least three ways of doing this:
- add a vmxoff sequence (with an exception handler) to
native_machine_emergency_restart(). while simplest, this will not
unblock INIT for other cpus
- add an emergency_restart notifier_block, and have kvm subscribe. This
has the disadvantage of being slightly complex, opening a tiny race
(emergency restart during kvm module initialization), and requiring IPIs
during emergency restart.
- move vmxon/vmxoff management out of the kvm module and into x86 core.
Bloats the core but reduces complexity. IPIs still required.
I think the notifier block is the way to go. Ingo, let me know what you
prefer.
--
error compiling committee.c: too many arguments to function
next parent reply other threads:[~2008-08-18 13:39 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20080812091950.61E3911D109@picon.linux-foundation.org>
2008-08-18 13:39 ` Avi Kivity [this message]
2008-08-18 14:03 ` [Bug 11219] KVM modules break emergency reboot Ingo Molnar
2008-08-23 18:07 2.6.27-rc4-git1: Reported regressions from 2.6.26 Rafael J. Wysocki
2008-08-23 18:10 ` [Bug #11219] KVM modules break emergency reboot Rafael J. Wysocki
-- strict thread matches above, loose matches on Subject: below --
2008-08-16 19:00 2.6.27-rc3-git3: Reported regressions from 2.6.26 Rafael J. Wysocki
2008-08-16 19:02 ` [Bug #11219] KVM modules break emergency reboot Rafael J. Wysocki
2008-08-09 22:40 2.6.27-rc2-git4: Reported regressions from 2.6.26 Rafael J. Wysocki
2008-08-09 22:43 ` [Bug #11219] KVM modules break emergency reboot Rafael J. Wysocki
2008-08-02 17:59 2.6.27-rc1-git4: Reported regressions from 2.6.26 Rafael J. Wysocki
2008-08-02 18:04 ` [Bug #11219] KVM modules break emergency reboot Rafael J. Wysocki
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