Re: [PATCH v4 06/17] PCI: add SIOV and IMS capability detection

Jason Gunthorpe
2020-11-03T12:44:08Z

On Tue, Nov 03, 2020 at 02:49:27AM +0000, Tian, Kevin wrote:

> > There is a missing hypercall to allow the guest to do this on its own,
> > presumably it will someday be fixed so IMS can work in guests.
>
> Hypercall is VMM specific, while IMS cap provides a VMM-agnostic
> interface so any guest driver (if following the spec) can seamlessly
> work on all hypervisors.

It is a *VMM* issue, not PCI. Adding a PCI cap to describe a VMM issue
is architecturally wrong.

IMS *can not work* in any hypervsior without some special
hypercall. Just block it in the platform code and forget about the PCI
cap.

Jason