Messages in this thread | | | From | Thomas Gleixner <> | Subject | Re: [patch 21/32] NTB/msi: Convert to msi_on_each_desc() | Date | Wed, 01 Dec 2021 19:41:05 +0100 |
| |
Dave,
please trim your replies.
On Wed, Dec 01 2021 at 09:28, Dave Jiang wrote:
> On 12/1/2021 3:16 AM, Thomas Gleixner wrote: >> Jason, >> >> CC+ IOMMU folks >> >> On Tue, Nov 30 2021 at 20:17, Jason Gunthorpe wrote: >>> On Tue, Nov 30, 2021 at 10:23:16PM +0100, Thomas Gleixner wrote: >> >> Though I fear there is also a use case for MSI-X and IMS tied to the >> same device. That network card you are talking about might end up using >> MSI-X for a control block and then IMS for the actual network queues >> when it is used as physical function device as a whole, but that's >> conceptually a different case. > > Hi Thomas. This is actually the IDXD usage for a mediated device passed > to a guest kernel when we plumb the pass through of IMS to the guest > rather than doing previous implementation of having a MSIX vector on > guest backed by IMS.
Which makes a lot of sense.
> The control block for the mediated device is emulated and therefore an > emulated MSIX vector will be surfaced as vector 0. However the queues > will backed by IMS vectors. So we end up needing MSIX and IMS coexist > running on the guest kernel for the same device.
Why? What's wrong with using straight MSI-X for all of them?
Thanks,
tglx
| |