Re: [PART1 RFC v2 06/10] svm: Add interrupt injection via AVIC

[Radim KrÄmÃÅ]

2016-03-09 12:10+0100, Paolo Bonzini:
> On 08/03/2016 22:54, Radim KrÄmÃÅ wrote:
>> 2016-03-07 16:36+0100, Paolo Bonzini:
>>> On 04/03/2016 21:46, Suravee Suthikulpanit wrote:
>>>> +static void svm_deliver_avic_intr(struct kvm_vcpu *vcpu, int vec)
>>>> +{
>>>> +	struct vcpu_svm *svm = to_svm(vcpu);
>>>> +
>>>> +	kvm_lapic_set_vector(vec, avic_get_bk_page_entry(svm, APIC_IRR));
>> 
>> (I think that smp_mb here would make sense, even though we're fine now
>>  thanks to re-checking vcpu->mode in kvm_vcpu_kick.
> 
> Right, though only a smp_mb__after_atomic() is required (which is a
> compiler barrier).  It is similarly required in vmx.

True, kvm_lapic_set_vector uses a lock prefix.

(I thought it behaves like atomic_set, which would require MFENCE for
 correct ordering here ... I don't like smp_mb__after_atomic much
 because of the discrepancy on some atomic operations.)

> Offtopic remark, kvm_make_request() and kvm_check_request() should
> probably have a smp_wmb() and a smp_rmb().

Yeah, noted.