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Tsirkin" Cc: David Stevens , Alyssa Ross , Albert Esteve , qemu-devel@nongnu.org, david@redhat.com, slp@redhat.com, =?UTF-8?B?QWxleCBCZW5uw6ll?= , stefanha@redhat.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Received-SPF: pass client-ip=170.10.129.124; envelope-from=jasowang@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=-0.01, RCVD_IN_MSPIKE_WL=-0.01, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Fri, Jul 12, 2024 at 1:48=E2=80=AFPM Michael S. Tsirkin = wrote: > > On Fri, Jul 12, 2024 at 11:06:49AM +0900, David Stevens wrote: > > On Thu, Jul 11, 2024 at 7:56=E2=80=AFPM Alyssa Ross wrot= e: > > > > > > Adding David Stevens, who implemented SHMEM_MAP and SHMEM_UNMAP in > > > crosvm a couple of years ago. > > > > > > David, I'd be particularly interested for your thoughts on the MEM_RE= AD > > > and MEM_WRITE commands, since as far as I know crosvm doesn't impleme= nt > > > anything like that. The discussion leading to those being added star= ts > > > here: > > > > > > https://lore.kernel.org/qemu-devel/20240604185416.GB90471@fedora.redh= at.com/ > > > > > > It would be great if this could be standardised between QEMU and cros= vm > > > (and therefore have a clearer path toward being implemented in other = VMMs)! > > > > Setting aside vhost-user for a moment, the DAX example given by Stefan > > won't work in crosvm today. > > > > Is universal access to virtio shared memory regions actually mandated > > by the virtio spec? Copying from virtiofs DAX to virtiofs sharing > > seems reasonable enough, but what about virtio-pmem to virtio-blk? > > What about screenshotting a framebuffer in virtio-gpu shared memory to > > virtio-scsi? I guess with some plumbing in the VMM, it's solvable in a > > virtualized environment. But what about when you have real hardware > > that speaks virtio involved? That's outside my wheelhouse, but it > > doesn't seem like that would be easy to solve. > > Yes, it can work for physical devices if allowed by host configuration. > E.g. VFIO supports that I think. Don't think VDPA does. > I guess you meant iommufd support here? Thanks