From 562a7d23bf9a2f978cea799af40a1b2b0b4fc71b Mon Sep 17 00:00:00 2001 From: Stefano Garzarella Date: Mon, 21 Nov 2022 11:11:01 +0100 Subject: vhost: mask VIRTIO_F_RING_RESET for vhost and vhost-user devices Commit 69e1c14aa2 ("virtio: core: vq reset feature negotation support") enabled VIRTIO_F_RING_RESET by default for all virtio devices. This feature is not currently emulated by QEMU, so for vhost and vhost-user devices we need to make sure it is supported by the offloaded device emulation (in-kernel or in another process). To do this we need to add VIRTIO_F_RING_RESET to the features bitmap passed to vhost_get_features(). This way it will be masked if the device does not support it. This issue was initially discovered with vhost-vsock and vhost-user-vsock, and then also tested with vhost-user-rng which confirmed the same issue. They fail when sending features through VHOST_SET_FEATURES ioctl or VHOST_USER_SET_FEATURES message, since VIRTIO_F_RING_RESET is negotiated by the guest (Linux >= v6.0), but not supported by the device. Fixes: 69e1c14aa2 ("virtio: core: vq reset feature negotation support") Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1318 Signed-off-by: Stefano Garzarella Message-Id: <20221121101101.29400-1-sgarzare@redhat.com> Reviewed-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin Reviewed-by: Stefan Hajnoczi Acked-by: Raphael Norwitz Acked-by: Jason Wang --- hw/virtio/vhost-user-rng.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) (limited to 'hw/virtio/vhost-user-rng.c') diff --git a/hw/virtio/vhost-user-rng.c b/hw/virtio/vhost-user-rng.c index 8b47287875..f9084cde58 100644 --- a/hw/virtio/vhost-user-rng.c +++ b/hw/virtio/vhost-user-rng.c @@ -16,6 +16,11 @@ #include "qemu/error-report.h" #include "standard-headers/linux/virtio_ids.h" +static const int feature_bits[] = { + VIRTIO_F_RING_RESET, + VHOST_INVALID_FEATURE_BIT +}; + static void vu_rng_start(VirtIODevice *vdev) { VHostUserRNG *rng = VHOST_USER_RNG(vdev); @@ -106,8 +111,10 @@ static void vu_rng_set_status(VirtIODevice *vdev, uint8_t status) static uint64_t vu_rng_get_features(VirtIODevice *vdev, uint64_t requested_features, Error **errp) { - /* No feature bits used yet */ - return requested_features; + VHostUserRNG *rng = VHOST_USER_RNG(vdev); + + return vhost_get_features(&rng->vhost_dev, feature_bits, + requested_features); } static void vu_rng_handle_output(VirtIODevice *vdev, VirtQueue *vq) -- cgit 1.4.1