From: Avi Kivity <avi@qumranet.com>
To: Marcelo Tosatti <mtosatti@redhat.com>
Cc: kvm-devel <kvm@vger.kernel.org>
Subject: Re: KVM: x86: do not execute halted vcpus (resend)
Date: Wed, 10 Sep 2008 21:42:05 +0300 [thread overview]
Message-ID: <48C814FD.5070507@qumranet.com> (raw)
In-Reply-To: <20080910183716.GA6373@dmt.cnet>
Marcelo Tosatti wrote:
>> Actually it does reproduce. If you reboot twice, the second reboot will
>> hang during reset (with cs:ip = f000:fff0). Plain Windows XP.
>>
>
> OK, easily reproducible by adding a sleep at the start of
> qemu_kvm_system_reset.
>
> The problem is that the vcpu HLT's between the KBD ioport write and the
> actual system reset by the IO thread. By then time there will be no
> event that takes it out of STATE_HALTED.
>
> The following fixes it, however older userspace will remain borked.
> Alternative is to special case f000:fff0 in-kernel. What is preferred?
>
>
Special-case the kvm_set_sregs ioctl with cs:eip f000:fff0 (and cr0.pe=0
for good measure).
--
Do not meddle in the internals of kernels, for they are subtle and quick to panic.
next prev parent reply other threads:[~2008-09-10 18:44 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-09-08 18:23 KVM: x86: do not execute halted vcpus (resend) Marcelo Tosatti
2008-09-09 14:15 ` Avi Kivity
2008-09-10 12:04 ` Avi Kivity
2008-09-10 18:37 ` Marcelo Tosatti
2008-09-10 18:42 ` Avi Kivity [this message]
-- strict thread matches above, loose matches on Subject: below --
2008-09-10 19:40 Marcelo Tosatti
2008-09-11 8:07 ` Avi Kivity
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