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