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Tsirkin" To: Jason Gunthorpe Cc: Jason Wang , Yishai Hadas , alex.williamson@redhat.com, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, parav@nvidia.com, feliu@nvidia.com, jiri@nvidia.com, kevin.tian@intel.com, joao.m.martins@oracle.com, leonro@nvidia.com, maorg@nvidia.com Subject: Re: [PATCH vfio 11/11] vfio/virtio: Introduce a vfio driver over virtio devices Message-ID: <20230928012650-mutt-send-email-mst@kernel.org> References: <20230922121132.GK13733@nvidia.com> <20230925122607.GW13733@nvidia.com> <20230925143708-mutt-send-email-mst@kernel.org> <20230926004059.GM13733@nvidia.com> <20230926014005-mutt-send-email-mst@kernel.org> <20230926135057.GO13733@nvidia.com> <20230927173221-mutt-send-email-mst@kernel.org> <20230927232005.GE339126@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230927232005.GE339126@nvidia.com> Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Wed, Sep 27, 2023 at 08:20:05PM -0300, Jason Gunthorpe wrote: > On Wed, Sep 27, 2023 at 05:38:55PM -0400, Michael S. Tsirkin wrote: > > On Tue, Sep 26, 2023 at 10:50:57AM -0300, Jason Gunthorpe wrote: > > > On Tue, Sep 26, 2023 at 01:42:52AM -0400, Michael S. Tsirkin wrote: > > > > On Mon, Sep 25, 2023 at 09:40:59PM -0300, Jason Gunthorpe wrote: > > > > > On Mon, Sep 25, 2023 at 03:44:11PM -0400, Michael S. Tsirkin wrote: > > > > > > > VDPA is very different from this. You might call them both mediation, > > > > > > > sure, but then you need another word to describe the additional > > > > > > > changes VPDA is doing. > > > > > > > > > > > > Sorry about hijacking the thread a little bit, but could you > > > > > > call out some of the changes that are the most problematic > > > > > > for you? > > > > > > > > > > I don't really know these details. > > > > > > > > Maybe, you then should desist from saying things like "It entirely fails > > > > to achieve the most important thing it needs to do!" You are not making > > > > any new friends with saying this about a piece of software without > > > > knowing the details. > > > > > > I can't tell you what cloud operators are doing, but I can say with > > > confidence that it is not the same as VDPA. As I said, if you want to > > > know more details you need to ask a cloud operator. > > > > So it's not the changes that are problematic, it's that you have > > customers who are not using vdpa. The "most important thing" that vdpa > > fails at is simply converting your customers from vfio to vdpa. > > I said the most important thing was that VFIO presents exactly the > same virtio device to the VM as the baremetal. Do you dispute that, > technically, VDPA does not actually achieve that? I dispute that it is the most important. The important thing is to have guests work. > Then why is it so surprising that people don't want a solution that > changes the vPCI ABI they worked hard to create in the first place? > > I'm still baffled why you think everyone should use vdpa.. > > Jason They shouldn't. If you want proprietary extensions then vfio is the way to go, I don't think vdpa will support that. -- MST