Re: [Xen-devel] [PATCH RFC] pass-through: sync pir to irr after msix vector been updated

[Jan Beulich <jbeulich@xxxxxxxx>]

On 19.09.2019 23:38, Joe Jin wrote:
> On 9/19/19 3:24 AM, Jan Beulich wrote:
>> What's
>> still missing is the further updating of pirq_dpci->gmsi.dest_vcpu_id
>> (as explained before, still visible in context above).
>>
> 
>  422
>  423         dest_vcpu_id = hvm_girq_dest_2_vcpu_id(d, dest, dest_mode);
>  424         pirq_dpci->gmsi.dest_vcpu_id = dest_vcpu_id;
> 
> dest_vcpu_id updated later by above code, do I missed something?

This piece of code

        if ( iommu_intpost )
        {
            if ( delivery_mode == dest_LowestPrio )
                vcpu = vector_hashing_dest(d, dest, dest_mode,
                                           pirq_dpci->gmsi.gvec);
            if ( vcpu )
                pirq_dpci->gmsi.posted = true;
        }

updates the vCPU to be delivered to. Right now, when the "posted"
flag is set, the dest_vcpu_id field is unused (as far as I was
able to tell), and hence didn't need setting. The way you intend
to change things, you want to use the field also in the "posted"
case, and hence you also should update it in the code path above.

But please double check all of this.

Jan

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