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 <maxime.coque...@redhat.com>
Cc: Michael S. Tsirkin <m...@redhat.com>
Cc: Stefan Hajnoczi <stefa...@redhat.com>
Signed-off-by: Alex Bennée <alex.ben...@linaro.org>
---
- we can't check for get_config/set_config as the stack squashed vdev
- use vhost-user-state to transmit this
---
include/hw/virtio/vhost-user.h | 1 +
hw/scsi/vhost-user-scsi.c | 1 +
hw/virtio/vhost-user.c | 46 ++++++++++++++++++++++++----------
3 files changed, 35 insertions(+), 13 deletions(-)
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);
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 b27b8c56e2..6ce082861b 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;
-
- 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;
+ /*
+ * 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 (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");
--
2.30.2
