From 56534930b5cd3a6c7259cfeba69f08ba28c8f62a Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Alex=20Benn=C3=A9e?= Date: Mon, 21 Mar 2022 15:30:36 +0000 Subject: [PATCH] hw/virtio/vhost-user: don't suppress F_CONFIG when supported MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Previously we would silently suppress VHOST_USER_PROTOCOL_F_CONFIG during the protocol negotiation if the QEMU stub hadn't implemented the vhost_dev_config_notifier. However this isn't the only way we can handle config messages, the existing vdc->get/set_config can do this as well. Lightly re-factor the code to check for both potential methods and instead of silently squashing the feature error out. It is unlikely that a vhost-user backend expecting to handle CONFIG messages will behave correctly if they never get sent. Fixes: 1c3e5a2617 ("vhost-user: back SET/GET_CONFIG requests with a protocol feature") Cc: Maxime Coquelin Cc: Michael S. Tsirkin Cc: Stefan Hajnoczi Signed-off-by: Alex Bennée Message-Id: <20220321153037.3622127-13-alex.bennee@linaro.org> Reviewed-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin --- hw/scsi/vhost-user-scsi.c | 1 + hw/virtio/vhost-user.c | 44 ++++++++++++++++++++++++---------- include/hw/virtio/vhost-user.h | 1 + 3 files changed, 34 insertions(+), 12 deletions(-) diff --git a/hw/scsi/vhost-user-scsi.c b/hw/scsi/vhost-user-scsi.c index 1b2f7eed98..9be21d07ee 100644 --- a/hw/scsi/vhost-user-scsi.c +++ b/hw/scsi/vhost-user-scsi.c @@ -121,6 +121,7 @@ static void vhost_user_scsi_realize(DeviceState *dev, Error **errp) vsc->dev.backend_features = 0; vqs = vsc->dev.vqs; + s->vhost_user.supports_config = true; ret = vhost_dev_init(&vsc->dev, &s->vhost_user, VHOST_BACKEND_TYPE_USER, 0, errp); if (ret < 0) { diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c index 6c8f722262..b0d417651d 100644 --- a/hw/virtio/vhost-user.c +++ b/hw/virtio/vhost-user.c @@ -1949,14 +1949,15 @@ static int vhost_user_postcopy_notifier(NotifierWithReturn *notifier, static int vhost_user_backend_init(struct vhost_dev *dev, void *opaque, Error **errp) { - uint64_t features, protocol_features, ram_slots; + uint64_t features, ram_slots; struct vhost_user *u; + VhostUserState *vus = (VhostUserState *) opaque; int err; assert(dev->vhost_ops->backend_type == VHOST_BACKEND_TYPE_USER); u = g_new0(struct vhost_user, 1); - u->user = opaque; + u->user = vus; u->dev = dev; dev->opaque = u; @@ -1967,6 +1968,10 @@ static int vhost_user_backend_init(struct vhost_dev *dev, void *opaque, } if (virtio_has_feature(features, VHOST_USER_F_PROTOCOL_FEATURES)) { + bool supports_f_config = vus->supports_config || + (dev->config_ops && dev->config_ops->vhost_dev_config_notifier); + uint64_t protocol_features; + dev->backend_features |= 1ULL << VHOST_USER_F_PROTOCOL_FEATURES; err = vhost_user_get_u64(dev, VHOST_USER_GET_PROTOCOL_FEATURES, @@ -1976,19 +1981,34 @@ static int vhost_user_backend_init(struct vhost_dev *dev, void *opaque, return -EPROTO; } - dev->protocol_features = - protocol_features & VHOST_USER_PROTOCOL_FEATURE_MASK; + /* + * We will use all the protocol features we support - although + * we suppress F_CONFIG if we know QEMUs internal code can not support + * it. + */ + protocol_features &= VHOST_USER_PROTOCOL_FEATURE_MASK; - if (!dev->config_ops || !dev->config_ops->vhost_dev_config_notifier) { - /* Don't acknowledge CONFIG feature if device doesn't support it */ - dev->protocol_features &= ~(1ULL << VHOST_USER_PROTOCOL_F_CONFIG); - } else if (!(protocol_features & - (1ULL << VHOST_USER_PROTOCOL_F_CONFIG))) { - error_setg(errp, "Device expects VHOST_USER_PROTOCOL_F_CONFIG " - "but backend does not support it."); - return -EINVAL; + if (supports_f_config) { + if (!virtio_has_feature(protocol_features, + VHOST_USER_PROTOCOL_F_CONFIG)) { + error_setg(errp, "vhost-user device %s expecting " + "VHOST_USER_PROTOCOL_F_CONFIG but the vhost-user backend does " + "not support it.", dev->vdev->name); + return -EPROTO; + } + } else { + if (virtio_has_feature(protocol_features, + VHOST_USER_PROTOCOL_F_CONFIG)) { + warn_reportf_err(*errp, "vhost-user backend supports " + "VHOST_USER_PROTOCOL_F_CONFIG for " + "device %s but QEMU does not.", + dev->vdev->name); + protocol_features &= ~(1ULL << VHOST_USER_PROTOCOL_F_CONFIG); + } } + /* final set of protocol features */ + dev->protocol_features = protocol_features; err = vhost_user_set_protocol_features(dev, dev->protocol_features); if (err < 0) { error_setg_errno(errp, EPROTO, "vhost_backend_init failed"); diff --git a/include/hw/virtio/vhost-user.h b/include/hw/virtio/vhost-user.h index e44a41bb70..6e0e8a71a3 100644 --- a/include/hw/virtio/vhost-user.h +++ b/include/hw/virtio/vhost-user.h @@ -22,6 +22,7 @@ typedef struct VhostUserState { CharBackend *chr; VhostUserHostNotifier notifier[VIRTIO_QUEUE_MAX]; int memory_slots; + bool supports_config; } VhostUserState; bool vhost_user_init(VhostUserState *user, CharBackend *chr, Error **errp);