Re: [Xen-devel] [PATCH V2 21/25] tools/libxc: Add a new interface to bind remapping format msi with pirq

[Chao Gao <chao.gao@xxxxxxxxx>]

On Wed, Aug 23, 2017 at 11:41:25AM +0100, Roger Pau Monné wrote:
>On Wed, Aug 09, 2017 at 04:34:22PM -0400, Lan Tianyu wrote:
>> From: Chao Gao <chao.gao@xxxxxxxxx>
>> 
>> Introduce a new binding relationship and provide a new interface to
>> manage the new relationship.
>> 
>> Signed-off-by: Chao Gao <chao.gao@xxxxxxxxx>
>> Signed-off-by: Lan Tianyu <tianyu.lan@xxxxxxxxx>
>> ---
>>          pirq_dpci->gmsi.posted = false;
>>          vcpu = (dest_vcpu_id >= 0) ? d->vcpu[dest_vcpu_id] : NULL;
>> -        if ( iommu_intpost )
>> +        /* Currently, don't use interrupt posting for guest's remapping 
>> MSIs */
>> +        if ( iommu_intpost && !ir )
>>          {
>>              if ( delivery_mode == dest_LowestPrio )
>>                  vcpu = vector_hashing_dest(d, dest, dest_mode,
>> @@ -435,7 +527,7 @@ int pt_irq_create_bind(
>>              hvm_migrate_pirqs(d->vcpu[dest_vcpu_id]);
>>  
>>          /* Use interrupt posting if it is supported. */
>> -        if ( iommu_intpost )
>> +        if ( iommu_intpost && !ir )
>
>So with interrupt remapping posted interrupts are not available...

Yes. We want to make thing simple. Currently, all vIRTE isn't
cached by vvtd and thus we needn't do anything when guest try to flush
vIRTE. If we use posted interrupt here, it means some information will
be cached by physical VTd. In that case, we should push effort to flush
correspond phyiscal IRTE. We don't include these patches in this
series.

Thanks
Chao


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