From 2c66de61f88dc9620a32239f7dd61524a57f66b0 Mon Sep 17 00:00:00 2001 From: Kevin Wolf Date: Fri, 15 Mar 2024 16:59:49 +0100 Subject: vdpa-dev: Fix initialisation order to restore VDUSE compatibility MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit VDUSE requires that virtqueues are first enabled before the DRIVER_OK status flag is set; with the current API of the kernel module, it is impossible to enable the opposite order in our block export code because userspace is not notified when a virtqueue is enabled. This requirement also mathces the normal initialisation order as done by the generic vhost code in QEMU. However, commit 6c482547 accidentally changed the order for vdpa-dev and broke access to VDUSE devices with this. This changes vdpa-dev to use the normal order again and use the standard vhost callback .vhost_set_vring_enable for this. VDUSE devices can be used with vdpa-dev again after this fix. vhost_net intentionally avoided enabling the vrings for vdpa and does this manually later while it does enable them for other vhost backends. Reflect this in the vhost_net code and return early for vdpa, so that the behaviour doesn't change for this device. Cc: qemu-stable@nongnu.org Fixes: 6c4825476a43 ('vdpa: move vhost_vdpa_set_vring_ready to the caller') Signed-off-by: Kevin Wolf Message-ID: <20240315155949.86066-1-kwolf@redhat.com> Reviewed-by: Eugenio Pérez Reviewed-by: Stefano Garzarella Signed-off-by: Kevin Wolf --- hw/net/vhost_net.c | 10 ++++++++++ 1 file changed, 10 insertions(+) (limited to 'hw/net/vhost_net.c') diff --git a/hw/net/vhost_net.c b/hw/net/vhost_net.c index e8e1661646..fd1a93701a 100644 --- a/hw/net/vhost_net.c +++ b/hw/net/vhost_net.c @@ -541,6 +541,16 @@ int vhost_set_vring_enable(NetClientState *nc, int enable) VHostNetState *net = get_vhost_net(nc); const VhostOps *vhost_ops = net->dev.vhost_ops; + /* + * vhost-vdpa network devices need to enable dataplane virtqueues after + * DRIVER_OK, so they can recover device state before starting dataplane. + * Because of that, we don't enable virtqueues here and leave it to + * net/vhost-vdpa.c. + */ + if (nc->info->type == NET_CLIENT_DRIVER_VHOST_VDPA) { + return 0; + } + nc->vring_enable = enable; if (vhost_ops && vhost_ops->vhost_set_vring_enable) { -- cgit 1.4.1