Re: [patch 21/32] NTB/msi: Convert to msi_on_each_desc()

Dave Jiang
2021-12-01T22:53:50Z

On 12/1/2021 3:03 PM, Thomas Gleixner wrote:
> On Wed, Dec 01 2021 at 14:49, Dave Jiang wrote:
>> On 12/1/2021 2:44 PM, Thomas Gleixner wrote:
>>> How that is backed on the host does not really matter. You can expose
>>> MSI-X to the guest with a INTx backing as well.
>>>
>>> I'm still failing to see the connection between the 9 MSIX vectors and
>>> the 2048 IMS vectors which I assume that this is the limitation of the
>>> physical device, right?
>> I think I was confused with what you were asking and was thinking you
>> are saying why can't we just have MSIX on guest backed by the MSIX on
>> the physical device and thought there would not be enough vectors to
>> service the many guests. I think I understand what your position is now
>> with the clarification above.
> This still depends on how this overall discussion about representation
> of all of this stuff is resolved.
>
>>> What needs a subdevice to expose?
> Can you answer that too please?

Sorry. So initial version of the IDXD sub-device is represented with a
single queue. It needs a command irq (emulated) and a completion irq
that is backed by a device vector (currently IMS).

>
> Thanks,
>
> tglx