From mboxrd@z Thu Jan  1 00:00:00 1970
From: Marcelo Tosatti <mtosatti@redhat.com>
Subject: Re: [PATCH] qemu-kvm initialize vcpu state after machine
	initialization
Date: Tue, 15 Dec 2009 10:51:37 -0200
Message-ID: <20091215125137.GA10077@amt.cnet>
References: <20091209174654.GA28056@amt.cnet> <4B20C058.5080307@redhat.com> <4B20C32B.7070005@redhat.com> <20091214203637.GA7120@amt.cnet> <20091215112037.GC8031@redhat.com> <20091215122415.GA9715@amt.cnet> <4B278194.7000209@redhat.com>
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Cc: Gleb Natapov <gleb@redhat.com>,
	Glauber de Oliveira Costa <gcosta@redhat.com>,
	kvm <kvm@vger.kernel.org>
To: Avi Kivity <avi@redhat.com>
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On Tue, Dec 15, 2009 at 02:31:16PM +0200, Avi Kivity wrote:
> On 12/15/2009 02:24 PM, Marcelo Tosatti wrote:
>>>
>>> This patch essentially revers commit 898c51c3. This commit fixes two
>>> races. First race is like this:
>>>
>>>       vcpu0                            vcpu1
>>>
>>>     starts running
>>>     loads lapic state into kernel
>>>     sends event to vcpu1
>>>                                     starts running
>>>                                     loads lapic state into kernel
>>>                                     overwrites event from vcpu0
>>>
>>> At the time 898c51c3 was committed the race was easily reproducible
>>> by starting VM with 16 cpus + seabios. Sometimes some vcpus lost INIT/SIPI
>>> events. Now I am not able to reproduce it even with this patch applied,
>>> so something else changed, but it doesn't make the race non existent or
>>> acceptable.
>>>      
>> Note qemu_kvm_load_lapic depends on env->created set (kvm_vcpu_inited),
>> so having init_vcpu+load_regs before signalling vcpu creation did not
>> fix this one (but yeah, thanks for the reminder on the races).
>>    
>
> So safest to revert and wait for a fixed patch?

Yeah, sorry.