Re: [RFC PATCH 2/3] vfio/ims: Support emulated interrupts

From: Jason Gunthorpe
Date: Thu Aug 24 2023 - 12:33:48 EST


On Thu, Aug 24, 2023 at 09:15:21AM -0700, Reinette Chatre wrote:
> Access from a guest to a virtual device may be either 'direct-path',
> where the guest interacts directly with the underlying hardware,
> or 'intercepted path' where the virtual device emulates operations.
>
> Support emulated interrupts that can be used to handle 'intercepted
> path' operations. For example, a virtual device may use 'intercepted
> path' for configuration. Doing so, configuration requests intercepted
> by the virtual device driver are handled within the virtual device
> driver with completion signaled to the guest without interacting with
> the underlying hardware.

Why does this have anything to do with IMS? I thought the point here
was that IMS was some back end to the MSI-X emulation - should a
purely emulated interrupt logically be part of the MSI code, not IMS?

Jason