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Subject: Re: [PATCH v2 1/4] KVM: add spinlock optimization framework
From: David Hildenbrand <david@redhat.com>
To: "Longpeng(Mike)" <longpeng2@huawei.com>, pbonzini@redhat.com,
        rkrcmar@redhat.com
Cc: agraf@suse.com, borntraeger@de.ibm.com, cohuck@redhat.com,
        christoffer.dall@linaro.org, marc.zyngier@arm.com,
        james.hogan@imgtec.com, kvm@vger.kernel.org,
        linux-kernel@vger.kernel.org, weidong.huang@huawei.com,
        arei.gonglei@huawei.com, wangxinxin.wang@huawei.com,
        longpeng.mike@gmail.com
References: <1502165135-4784-1-git-send-email-longpeng2@huawei.com>
 <1502165135-4784-2-git-send-email-longpeng2@huawei.com>
 <8f4e336d-82b2-9148-eac3-ad411e6a16ef@redhat.com>
Organization: Red Hat GmbH
Message-ID: <8c0c74eb-da08-aee1-0037-d8b9c9021b41@redhat.com>
Date: Tue, 8 Aug 2017 10:44:43 +0200
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On 08.08.2017 10:42, David Hildenbrand wrote:
> 
>> +bool kvm_arch_vcpu_in_kernel(struct kvm_vcpu *vcpu)
>> +{
>> +	return false;
>> +}
> 
> why don't we need an EXPORT_SYMBOL here?
> 
>> +
>>  /* Just ensure a guest exit from a particular CPU */
>>  static void exit_vm_noop(void *info)
>>  {
>> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
>> index 15252d7..e7720d2 100644
>> --- a/virt/kvm/kvm_main.c
>> +++ b/virt/kvm/kvm_main.c
>> @@ -2317,7 +2317,7 @@ static bool kvm_vcpu_eligible_for_directed_yield(struct kvm_vcpu *vcpu)
>>  #endif
>>  }
>>  
>> -void kvm_vcpu_on_spin(struct kvm_vcpu *me)
>> +void kvm_vcpu_on_spin(struct kvm_vcpu *me, bool me_in_kern)
>>  {
>>  	struct kvm *kvm = me->kvm;
>>  	struct kvm_vcpu *vcpu;
>> @@ -2348,6 +2348,8 @@ void kvm_vcpu_on_spin(struct kvm_vcpu *me)
>>  				continue;
>>  			if (swait_active(&vcpu->wq) && !kvm_arch_vcpu_runnable(vcpu))
>>  				continue;
>> +			if (me_in_kern && !kvm_arch_vcpu_in_kernel(vcpu))
>> +				continue;
> 
> 
> hm, does this patch compile? (me_in_kern)

pardon me, missed the parameter, so ignore this comment. comment
regarding splitting up below still holds :)

> 
> I would even move this to an other patch.
> 
> Maybe even split into
> 
> a) introducing kvm_arch_vcpu_in_kernel() for all archs
> b) modifying kvm_vcpu_on_spin(), passing the result from
> kvm_arch_vcpu_in_kernel()
> c) filling kvm_arch_vcpu_in_kernel() with life for different archs
> (multiple patches)
> d) pimping kvm_vcpu_on_spin()
> 
>>  			if (!kvm_vcpu_eligible_for_directed_yield(vcpu))
>>  				continue;
>>  
>>
> 
> 


-- 

Thanks,

David