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Tsirkin" To: Eugenio Perez Martin Cc: Xuan Zhuo , Jason Wang , Lei Yang , qemu-devel@nongnu.org Subject: Re: [PATCH] virtio-net: not enable vq reset feature unconditionally Message-ID: <20230508062210-mutt-send-email-mst@kernel.org> References: <20230504101447.389398-1-eperezma@redhat.com> <1683339216.3364966-2-xuanzhuo@linux.alibaba.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Received-SPF: pass client-ip=170.10.133.124; envelope-from=mst@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_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 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 Mon, May 08, 2023 at 11:09:46AM +0200, Eugenio Perez Martin wrote: > On Sat, May 6, 2023 at 4:25 AM Xuan Zhuo wrote: > > > > On Thu, 4 May 2023 12:14:47 +0200, =?utf-8?q?Eugenio_P=C3=A9rez?= wrote: > > > The commit 93a97dc5200a ("virtio-net: enable vq reset feature") enables > > > unconditionally vq reset feature as long as the device is emulated. > > > This makes impossible to actually disable the feature, and it causes > > > migration problems from qemu version previous than 7.2. > > > > > > The entire final commit is unneeded as device system already enable or > > > disable the feature properly. > > > > > > This reverts commit 93a97dc5200a95e63b99cb625f20b7ae802ba413. > > > Fixes: 93a97dc5200a ("virtio-net: enable vq reset feature") > > > Signed-off-by: Eugenio Pérez > > > > > > --- > > > Tested by checking feature bit at /sys/devices/pci.../virtio0/features > > > enabling and disabling queue_reset virtio-net feature and vhost=on/off > > > on net device backend. > > > > Do you mean that this feature cannot be closed? > > > > I tried to close in the guest, it was successful. > > > > I'm not sure what you mean with close. If the device dataplane is > emulated in qemu (vhost=off), I'm not able to make the device not > offer it. > > > In addition, in this case, could you try to repair the problem instead of > > directly revert. > > > > I'm not following this. The revert is not to always disable the feature. > > By default, the feature is enabled. If cmdline states queue_reset=on, > the feature is enabled. That is true both before and after applying > this patch. > > However, in qemu master, queue_reset=off keeps enabling this feature > on the device. It happens that there is a commit explicitly doing > that, so I'm reverting it. > > Let me know if that makes sense to you. > > Thanks! question is this: DEFINE_PROP_BIT64("queue_reset", _state, _field, \ VIRTIO_F_RING_RESET, true) don't we need compat for 7.2 and back for this property? -- MST