From: Avi Kivity <avi@qumranet.com>
To: Shaohua Li <shaohua.li@intel.com>
Cc: kvm-devel <kvm-devel@lists.sourceforge.net>,
lkml <linux-kernel@vger.kernel.org>, Ingo Molnar <mingo@elte.hu>
Subject: Re: [RFC 1/8]KVM: fix bugs in kvm sched integration patch
Date: Tue, 24 Jul 2007 08:35:04 +0300 [thread overview]
Message-ID: <46A58F88.9050906@qumranet.com> (raw)
In-Reply-To: <1185241544.24201.15.camel@sli10-conroe.sh.intel.com>
Shaohua Li wrote:
>>
>>> 1. vmcs_readl/vmcs_writel are called with preempt enabled
>>>
>>>
>> Why is that bad?
>>
> 1. raw_smp_processor_id()
> 2. migrate to other cpu
> 3. current->kvm_vcpu->cpu != the cpu id of step 1.
> you will see the warning.
>
Ah, that code is gone from preempt-hooks, hence I didn't understand you.
The current version of the patchset does not change
vmcs_readl/vmcs_writel. So I think everything is safe.
--
Do not meddle in the internals of kernels, for they are subtle and quick to panic.
WARNING: multiple messages have this Message-ID (diff)
From: Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
To: Shaohua Li <shaohua.li-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
Cc: kvm-devel
<kvm-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org>,
lkml <linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>
Subject: Re: [RFC 1/8]KVM: fix bugs in kvm sched integration patch
Date: Tue, 24 Jul 2007 08:35:04 +0300 [thread overview]
Message-ID: <46A58F88.9050906@qumranet.com> (raw)
In-Reply-To: <1185241544.24201.15.camel-yAZKuqJtXNMXR+D7ky4Foa2pdiUAq4bhAL8bYrjMMd8@public.gmane.org>
Shaohua Li wrote:
>>
>>> 1. vmcs_readl/vmcs_writel are called with preempt enabled
>>>
>>>
>> Why is that bad?
>>
> 1. raw_smp_processor_id()
> 2. migrate to other cpu
> 3. current->kvm_vcpu->cpu != the cpu id of step 1.
> you will see the warning.
>
Ah, that code is gone from preempt-hooks, hence I didn't understand you.
The current version of the patchset does not change
vmcs_readl/vmcs_writel. So I think everything is safe.
--
Do not meddle in the internals of kernels, for they are subtle and quick to panic.
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next prev parent reply other threads:[~2007-07-24 5:35 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-07-23 6:51 [RFC 1/8]KVM: fix bugs in kvm sched integration patch Shaohua Li
2007-07-23 6:51 ` Shaohua Li
2007-07-23 10:46 ` Avi Kivity
2007-07-23 10:46 ` Avi Kivity
2007-07-24 1:45 ` Shaohua Li
2007-07-24 1:45 ` Shaohua Li
2007-07-24 5:35 ` Avi Kivity [this message]
2007-07-24 5:35 ` Avi Kivity
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