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Tsirkin" , Halil Pasic Subject: Re: [virtio-dev] Re: [RFC PATCH 1/1] virtio: write back features before verify In-Reply-To: <20211005072110-mutt-send-email-mst@kernel.org> Organization: Red Hat GmbH References: <20211003070030.658fc94e.pasic@linux.ibm.com> <20211003021027-mutt-send-email-mst@kernel.org> <20211003032253-mutt-send-email-mst@kernel.org> <87ee912e45.fsf@redhat.com> <20211004083455-mutt-send-email-mst@kernel.org> <878rz83lx0.fsf@redhat.com> <20211004110152-mutt-send-email-mst@kernel.org> <87zgro23r1.fsf@redhat.com> <20211004160005-mutt-send-email-mst@kernel.org> <20211005131751.53175b10.pasic@linux.ibm.com> <20211005072110-mutt-send-email-mst@kernel.org> User-Agent: Notmuch/0.32.1 (https://notmuchmail.org) Date: Tue, 05 Oct 2021 17:20:29 +0200 Message-ID: <87fstf1osi.fsf@redhat.com> MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Received-SPF: pass client-ip=170.10.133.124; envelope-from=cohuck@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -28 X-Spam_score: -2.9 X-Spam_bar: -- X-Spam_report: (-2.9 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.066, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H2=-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, Christian Borntraeger , qemu-devel@nongnu.org, Jason Wang , linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, Xie Yongji , virtio-dev@lists.oasis-open.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Tue, Oct 05 2021, "Michael S. Tsirkin" wrote: > On Tue, Oct 05, 2021 at 01:17:51PM +0200, Halil Pasic wrote: >> On Mon, 4 Oct 2021 16:01:12 -0400 >> "Michael S. Tsirkin" wrote: >> >> > > >> > > Ok, so what about something like >> > > >> > > "If FEATURES_OK is not set, the driver MAY change the set of features it >> > > accepts." >> > > >> > > in the device initialization section? >> > >> > Maybe "as long as". However Halil implied that some features are not >> > turned off properly if that happens. Halil could you pls provide >> > some examples? >> >> >> >> static void virtio_net_set_features(VirtIODevice *vdev, uint64_t features) >> { >> ... >> if (virtio_has_feature(features, VIRTIO_NET_F_STANDBY)) { >> qapi_event_send_failover_negotiated(n->netclient_name); >> qatomic_set(&n->failover_primary_hidden, false); >> failover_add_primary(n, &err); >> if (err) { >> warn_report_err(err); >> } >> } >> } >> >> This is probably the only one in QEMU. Back then I stopped looking >> after the first hit. After some grepping, I agree that this seems to be the only one. >> >> Regards, >> Halil > > Hmm ok more failover issues :( > This stuff really should be moved to set_status. Yes, F_STANDBY does not exist for legacy, so performing those actions when FEATURES_OK is set looks like the right thing to do.