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Tsirkin" Subject: Re: [RFC PATCH 1/1] virtio: write back features before verify Message-ID: <20211005124634.2a774796.pasic@linux.ibm.com> In-Reply-To: <20211005035014-mutt-send-email-mst@kernel.org> References: <20210930012049.3780865-1-pasic@linux.ibm.com> <20210930070444-mutt-send-email-mst@kernel.org> <20211001092125.64fef348.pasic@linux.ibm.com> <20211002055605-mutt-send-email-mst@kernel.org> <87bl452d90.fsf@redhat.com> <20211004090018-mutt-send-email-mst@kernel.org> <20211005092539.145c9cc4.pasic@linux.ibm.com> <20211005035014-mutt-send-email-mst@kernel.org> Organization: IBM X-Mailer: Claws Mail 3.17.8 (GTK+ 2.24.32; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: dISC-4Fas47o_uRyUynz0RAGrkvMT9az X-Proofpoint-GUID: tCE_4RJXbd3HchYj9DxiZqvQ87w1z1GS X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.182.1,Aquarius:18.0.790,Hydra:6.0.391,FMLib:17.0.607.475 definitions=2021-10-04_05,2021-10-04_01,2020-04-07_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 lowpriorityscore=0 spamscore=0 bulkscore=0 suspectscore=0 mlxscore=0 priorityscore=1501 adultscore=0 malwarescore=0 phishscore=0 clxscore=1015 mlxlogscore=999 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2109230001 definitions=main-2110050061 Received-SPF: pass client-ip=148.163.158.5; envelope-from=pasic@linux.ibm.com; helo=mx0b-001b2d01.pphosted.com X-Spam_score_int: -19 X-Spam_score: -2.0 X-Spam_bar: -- X-Spam_report: (-2.0 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, 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: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-s390@vger.kernel.org, markver@us.ibm.com, Xie Yongji , Jason Wang , Cornelia Huck , qemu-devel@nongnu.org, linux-kernel@vger.kernel.org, Halil Pasic , Christian Borntraeger , virtualization@lists.linux-foundation.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Tue, 5 Oct 2021 03:53:17 -0400 "Michael S. Tsirkin" wrote: > > Wouldn't a call from transport code into virtio core > > be more handy? What I have in mind is stuff like vhost-user and vdpa. My > > understanding is, that for vhost setups where the config is outside qemu, > > we probably need a new command that tells the vhost backend what > > endiannes to use for config. I don't think we can use > > VHOST_USER_SET_VRING_ENDIAN because that one is on a virtqueue basis > > according to the doc. So for vhost-user and similar we would fire that > > command and probably also set the filed, while for devices for which > > control plane is handled by QEMU we would just set the field. > > > > Does that sound about right? > > I'm fine either way, but when would you invoke this? > With my idea backends can check the field when get_config > is invoked. > > As for using this in VHOST, can we maybe re-use SET_FEATURES? > > Kind of hacky but nice in that it will actually make existing backends > work... Basically the equivalent of this patch, just on the vhost interface, right? Could work I have to look into it :)