From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Wed, 10 Apr 2019 10:25:57 +0200 From: Cornelia Huck Subject: Re: [RFC PATCH 05/12] s390/cio: add protected virtualization support to cio Message-ID: <20190410102557.1ba89d96.cohuck@redhat.com> In-Reply-To: <20190410021044.4da3e847@oc2783563651> References: <20190404231622.52531-1-pasic@linux.ibm.com> <20190404231622.52531-6-pasic@linux.ibm.com> <20190409195548.6dea6e40.cohuck@redhat.com> <20190410021044.4da3e847@oc2783563651> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: kvm-owner@vger.kernel.org List-Archive: List-Post: To: Halil Pasic Cc: kvm@vger.kernel.org, linux-s390@vger.kernel.org, Martin Schwidefsky , Sebastian Ott , virtualization@lists.linux-foundation.org, Christian Borntraeger , Viktor Mihajlovski , Vasily Gorbik , Janosch Frank , Claudio Imbrenda , Farhan Ali , Eric Farman List-ID: On Wed, 10 Apr 2019 02:10:44 +0200 Halil Pasic wrote: > On Tue, 9 Apr 2019 19:55:48 +0200 > Cornelia Huck wrote: > > > On Fri, 5 Apr 2019 01:16:15 +0200 > > Halil Pasic wrote: > > > Thus we need to make sure any memory that is used for communication with > > > the hypervisor is shared. > > > > In this context, does 'hypervisor' always mean 'QEMU/KVM'? If Other > > Hypervisors implement protected virtualization, we probably need to > > make sure that all common I/O layer control blocks are in the dma area > > (including e.g. QDIO), not just what virtio-ccw devices use. > > > > Hypervisor could theoretically be something different than QEMU/KVM. Yet, > as stated before, this series is about getting virtio-ccw working > (modulo the TODOs). Sure, just wanted to point it out. If this is "enable the common I/O layer, except for QDIO" or so, that would sound fine to me :) > > [..] > > > > > > > > So, this leaves some things I'm not sure about, especially as I do not > > know the architecture of this new feature. > > > > - This applies only to asynchronously handled things, it seems? So > > things like control blocks modified by stsch/msch/etc does not need > > special treatment? > > I had a feeble attempt at explaining this in the cover letter: > > * make sure that virtio-ccw specific stuff uses shared memory when > talking to the hypervisor (except communication blocks like ORB, these > are handled by the hypervisor) > > Unfortunately the last 'hypervisor' was supposed to be 'ultravisor'. > > I.e. the ultravisor will take care of exposing the control blocks > to the hypervisor (and of changes as well). Yeah, that "control blocks" or "communication blocks" leaves me a bit fuzzy :) So, what is a high-level summary of areas that need the treatment? What I get from looking at the patches so far, it's: - stuff that is written by the hypervisor's interrupt injection code: IRB, indicators, etc. - buffers that are filled by a channel program: sense, sense id, etc. - ccws themselves (because of translation?)