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charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=170.10.133.124; envelope-from=lvivier@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -35 X-Spam_score: -3.6 X-Spam_bar: --- X-Spam_report: (-3.6 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.699, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.08, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H4=-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: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Juan Quintela , Jens Freimann , "Michael S. Tsirkin" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 02/08/2021 06:50, Jason Wang wrote: > > 在 2021/7/30 上午3:19, Laurent Vivier 写道: >> Add virtio_queue_disable()/virtio_queue_enable() to disable/enable a queue >> by setting vring.num to 0 (or num_default). >> This is needed to be able to disable a guest driver from the host side > > > I suspect this won't work correclty for vhost. With my test it seems to work with vhost too. > > And I believe we should only do this after the per queue enabling/disabling is supported > by the spec. > > (only MMIO support that AFAIK) I don't want to modify the spec. I need something that works without modifying existing (old) drivers. The idea is to be able to disable the virtio-net kernel driver from QEMU if the driver is too old (i.e. it doesn't support STANDBY feature). Setting vring.num to 0 forces the kernel driver to exit on error in the probe function. It's what I want: the device is present but disabled (the driver is not loaded). Any other suggestion? Thanks, Laurent > Thanks > > >> >> Signed-off-by: Laurent Vivier >> --- >>   include/hw/virtio/virtio.h |  2 ++ >>   hw/virtio/virtio.c         | 10 ++++++++++ >>   2 files changed, 12 insertions(+) >> >> diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h >> index 8bab9cfb7507..6a3f71b4cd88 100644 >> --- a/include/hw/virtio/virtio.h >> +++ b/include/hw/virtio/virtio.h >> @@ -251,6 +251,8 @@ void virtio_config_modern_writel(VirtIODevice *vdev, >>                                    uint32_t addr, uint32_t data); >>   void virtio_queue_set_addr(VirtIODevice *vdev, int n, hwaddr addr); >>   hwaddr virtio_queue_get_addr(VirtIODevice *vdev, int n); >> +void virtio_queue_enable(VirtIODevice *vdev, int n); >> +void virtio_queue_disable(VirtIODevice *vdev, int n); >>   void virtio_queue_set_num(VirtIODevice *vdev, int n, int num); >>   int virtio_queue_get_num(VirtIODevice *vdev, int n); >>   int virtio_queue_get_max_num(VirtIODevice *vdev, int n); >> diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c >> index 874377f37a70..fa5228c1a2d6 100644 >> --- a/hw/virtio/virtio.c >> +++ b/hw/virtio/virtio.c >> @@ -2244,6 +2244,16 @@ void virtio_queue_set_rings(VirtIODevice *vdev, int n, hwaddr desc, >>       virtio_init_region_cache(vdev, n); >>   } >>   +void virtio_queue_disable(VirtIODevice *vdev, int n) >> +{ >> +    vdev->vq[n].vring.num = 0; >> +} >> + >> +void virtio_queue_enable(VirtIODevice *vdev, int n) >> +{ >> +    vdev->vq[n].vring.num = vdev->vq[n].vring.num_default; >> +} >> + >>   void virtio_queue_set_num(VirtIODevice *vdev, int n, int num) >>   { >>       /* Don't allow guest to flip queue between existent and >