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Re: [Qemu-devel] [PATCH] cpu: smp_wmb before lauching cpus.
From: |
Jan Kiszka |
Subject: |
Re: [Qemu-devel] [PATCH] cpu: smp_wmb before lauching cpus. |
Date: |
Thu, 05 Jul 2012 13:58:14 +0200 |
User-agent: |
Mozilla/5.0 (X11; U; Linux i686 (x86_64); de; rv:1.8.1.12) Gecko/20080226 SUSE/2.0.0.12-1.1 Thunderbird/2.0.0.12 Mnenhy/0.7.5.666 |
On 2012-07-05 13:02, liu ping fan wrote:
> On Thu, Jul 5, 2012 at 6:16 PM, Jan Kiszka <address@hidden> wrote:
>> On 2012-07-05 12:10, liu ping fan wrote:
>>> On Thu, Jul 5, 2012 at 2:46 PM, Jan Kiszka <address@hidden> wrote:
>>>> On 2012-07-05 04:18, Liu Ping Fan wrote:
>>>>> Vcpu state must be set completely before receiving INIT-IPI,SIPI
>>>>>
>>>>> Signed-off-by: Liu Ping Fan <address@hidden>
>>>>> ---
>>>>> kvm.h | 1 +
>>>>> 1 files changed, 1 insertions(+), 0 deletions(-)
>>>>>
>>>>> diff --git a/kvm.h b/kvm.h
>>>>> index 9c7b0ea..5b3c228 100644
>>>>> --- a/kvm.h
>>>>> +++ b/kvm.h
>>>>> @@ -198,6 +198,7 @@ static inline void
>>>>> cpu_synchronize_post_init(CPUArchState *env)
>>>>> {
>>>>> if (kvm_enabled()) {
>>>>> kvm_cpu_synchronize_post_init(env);
>>>>> + smp_wmb();
>>>>> }
>>>>> }
>>>>>
>>>>>
>>>>
>>>> In theory, there should be no vcpu kick-off after this without some
>>>> locking operations involved that imply barriers. Did you see real
>>>
>>> Yeah, but what if it is non-x86?
>>
>> The locking I'm referring to is arch independent.
>>
>>>> inconsistencies without this explicit one?
>>
>> Again: Did you see real issues or is this based on static analysis?
>>
> Just on static analysis
Then please describe - also for the changelog - at least one case in
details where this is needed.
Thanks,
Jan
--
Siemens AG, Corporate Technology, CT RTC ITP SDP-DE
Corporate Competence Center Embedded Linux