Re: Remaining passthrough/VT-d tasks list

[Avi Kivity <avi@redhat.com>]

Dong, Eddie wrote:
>> Shared guest interrupts is a prerequisite for merging
>> into mainline. Without this, device assignment is useless
>> in anything but a benchmark scenario.  I won't push
>> device assignment for 2.6.28 without it. 
>>
>> Shared host interrupts are a different matter; which one
>> did you mean? 
>>
>>     
> Avi:
> 	How about we think in other way? The top usage model of IOMMU is
> SR-IOV in my mind, at least for enterprise usage model. We are pushing
> the SR-IOV patch for 2.6.28, and are continuously polishing the patch.
> Even if it missed the 2.6.28 merge windows (unlikely?), we could be able
> to ask OSVs to take the SR-IOV patch seperately before code froze since
> it is very small, but it is hard to ask for taking whole IOMMU patches.
>
> 	In Xen side, IOMMU is there, MSI-x is there, so SR-IOV patch is
> the only one missed to enable SR-IOV. In KVM side, very likely we can
> get MSI patch down soon before chinese holiday, and we of course will
> spend tons of effort in qualities too. Should we target this? If yes, we
> put MSI patch and push 2.6.28 as 1st priority. We would be able to see
> next major release of VMM using KVM have HW IO virtualization
> technology: Close to native performance, non sacriface of IO sharing,
> minimal CPU utilization etc.
> 	For those legacy PCI pass thru support, we can continue improve
> it too.
>   

I don't see how this relates to shared guest interrupts.  Whatever you 
have on the host side, you still need to support shared guest 
interrupts.  The only way to avoid the issue is by using MSI for the 
guest, and even then we still have to support interrupt sharing since 
not all guests have MSI support.

-- 
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.