On Wed, Feb 17, 2021, Kalra, Ashish wrote: > From: Sean Christopherson <sea...@google.com> > On Thu, Feb 04, 2021, Ashish Kalra wrote: > > From: Brijesh Singh <brijesh.si...@amd.com> > > > > The ioctl is used to retrieve a guest's shared pages list. > > >What's the performance hit to boot time if KVM_HC_PAGE_ENC_STATUS is passed > >through to userspace? That way, userspace could manage the set of pages >in > >whatever data structure they want, and these get/set ioctls go away. > > What is the advantage of passing KVM_HC_PAGE_ENC_STATUS through to user-space > ? > > As such it is just a simple interface to get the shared page list via the > get/set ioctl's. simply an array is passed to these ioctl to get/set the > shared pages list.
It eliminates any probability of the kernel choosing the wrong data structure, and it's two fewer ioctls to maintain and test. > >Also, aren't there plans for an in-guest migration helper? If so, do we > >have any idea what that interface will look like? E.g. if we're going to > >end up with a full >fledged driver in the guest, why not bite the bullet now > >and bypass KVM entirely? > > Even the in-guest migration helper will be using page encryption status > hypercalls, so some interface is surely required. If it's a driver with a more extensive interace, then the hypercalls can be replaced by a driver operation. That's obviously a big if, though. > Also the in-guest migration will be mainly an OVMF component, won't really > be a full fledged kernel driver in the guest. Is there code and/or a description of what the proposed helper would look like?
