RE: kvm/ia64: Fix halt emulation logic.

Marcelo Tosatti wrote:
> Hi Xiantao,
> 
> On Wed, Oct 15, 2008 at 09:47:24PM +0800, Zhang, Xiantao wrote:
>> +		expires = div64_u64(itc_diff, cyc_per_usec);
>> +		kt = ktime_set(0, 1000 * expires);
>> +
>> +		down_read(&vcpu->kvm->slots_lock);
>> +		vcpu->arch.ht_active = 1;
>> +		hrtimer_start(p_ht, kt, HRTIMER_MODE_ABS);
>> 
>> -	if (irqchip_in_kernel(vcpu->kvm)) {
>>  		vcpu->arch.mp_state = KVM_MP_STATE_HALTED;
>>  		kvm_vcpu_block(vcpu);
>>  		hrtimer_cancel(p_ht);
>>  		vcpu->arch.ht_active = 0;
>> 
>> +		if (test_and_clear_bit(KVM_REQ_UNHALT, &vcpu->requests))
>> +			if (vcpu->arch.mp_state == KVM_MP_STATE_HALTED)
>> +				vcpu->arch.mp_state = +					KVM_MP_STATE_RUNNABLE;
>> +		up_read(&vcpu->kvm->slots_lock);
> 
> You should release slots_lock when blocking via kvm_vcpu_block().
> Otherwise paths that grab it for write will depend on these vcpus to
> unhalt.
> 
> BTW, none of the data structures in this section of code should be
> protected by slots_lock?

Hi, Marcelo
	Agree, I have made a patch to remove it last week, but seems Avi hasn't commited it yet.  

Avi, 
	Could you help to commit the attached patch, even though it is just a potential issue(write lock is very rare in current code). 
Thanks
Xiantao