From 4daa5054c599c8aec70f1264a01341a15921c145 Mon Sep 17 00:00:00 2001 From: Stefano Garzarella Date: Wed, 30 Nov 2022 11:24:36 +0000 Subject: vhost: enable vrings in vhost_dev_start() for vhost-user devices Commit 02b61f38d3 ("hw/virtio: incorporate backend features in features") properly negotiates VHOST_USER_F_PROTOCOL_FEATURES with the vhost-user backend, but we forgot to enable vrings as specified in docs/interop/vhost-user.rst: If ``VHOST_USER_F_PROTOCOL_FEATURES`` has not been negotiated, the ring starts directly in the enabled state. If ``VHOST_USER_F_PROTOCOL_FEATURES`` has been negotiated, the ring is initialized in a disabled state and is enabled by ``VHOST_USER_SET_VRING_ENABLE`` with parameter 1. Some vhost-user front-ends already did this by calling vhost_ops.vhost_set_vring_enable() directly: - backends/cryptodev-vhost.c - hw/net/virtio-net.c - hw/virtio/vhost-user-gpio.c But most didn't do that, so we would leave the vrings disabled and some backends would not work. We observed this issue with the rust version of virtiofsd [1], which uses the event loop [2] provided by the vhost-user-backend crate where requests are not processed if vring is not enabled. Let's fix this issue by enabling the vrings in vhost_dev_start() for vhost-user front-ends that don't already do this directly. Same thing also in vhost_dev_stop() where we disable vrings. [1] https://gitlab.com/virtio-fs/virtiofsd [2] https://github.com/rust-vmm/vhost/blob/240fc2966/crates/vhost-user-backend/src/event_loop.rs#L217 Fixes: 02b61f38d3 ("hw/virtio: incorporate backend features in features") Reported-by: German Maglione Tested-by: German Maglione Signed-off-by: Stefano Garzarella Acked-by: Raphael Norwitz Message-Id: <20221123131630.52020-1-sgarzare@redhat.com> Signed-off-by: Alex Bennée Reviewed-by: Michael S. Tsirkin Message-Id: <20221130112439.2527228-3-alex.bennee@linaro.org> Signed-off-by: Michael S. Tsirkin --- hw/net/vhost_net.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'hw/net') diff --git a/hw/net/vhost_net.c b/hw/net/vhost_net.c index 26e4930676..043058ff43 100644 --- a/hw/net/vhost_net.c +++ b/hw/net/vhost_net.c @@ -259,7 +259,7 @@ static int vhost_net_start_one(struct vhost_net *net, goto fail_notifiers; } - r = vhost_dev_start(&net->dev, dev); + r = vhost_dev_start(&net->dev, dev, false); if (r < 0) { goto fail_start; } @@ -308,7 +308,7 @@ fail: if (net->nc->info->poll) { net->nc->info->poll(net->nc, true); } - vhost_dev_stop(&net->dev, dev); + vhost_dev_stop(&net->dev, dev, false); fail_start: vhost_dev_disable_notifiers(&net->dev, dev); fail_notifiers: @@ -329,7 +329,7 @@ static void vhost_net_stop_one(struct vhost_net *net, if (net->nc->info->poll) { net->nc->info->poll(net->nc, true); } - vhost_dev_stop(&net->dev, dev); + vhost_dev_stop(&net->dev, dev, false); if (net->nc->info->stop) { net->nc->info->stop(net->nc); } @@ -606,7 +606,7 @@ err_start: assert(r >= 0); } - vhost_dev_stop(&net->dev, vdev); + vhost_dev_stop(&net->dev, vdev, false); return r; } -- cgit v1.2.3-55-g7522