| Message ID | 20221018023651.1359420-1-yajunw@nvidia.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | vhost-user: Fix out of order vring host notification handling | expand |
Yajun Wu <yajunw@nvidia.com> writes: > vhost backend sends host notification for every VQ. If backend creates > VQs in parallel, the VHOST_USER_SLAVE_VRING_HOST_NOTIFIER_MSG may > arrive to QEMU in different order than incremental queue index order. > > For example VQ 1's message arrive earlier than VQ 0's: > After alloc VhostUserHostNotifier for VQ 1. GPtrArray becomes > > [ nil, VQ1 pointer ] > > After alloc VhostUserHostNotifier for VQ 0. GPtrArray becomes > > [ VQ0 pointer, nil, VQ1 pointer ] > > This is wrong. fetch_notifier will return NULL for VQ 1 in > vhost_user_get_vring_base, causes host notifier miss removal(leak). > > The fix is to remove current element from GPtrArray, make the right > position for element to insert. > > Fixes: 503e355465 ("virtio/vhost-user: dynamically assign VhostUserHostNotifiers") > Signed-off-by: Yajun Wu <yajunw@nvidia.com> > Acked-by: Parav Pandit <parav@nvidia.com> > > --- > hw/virtio/vhost-user.c | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c > index 03415b6c95..d256ce589b 100644 > --- a/hw/virtio/vhost-user.c > +++ b/hw/virtio/vhost-user.c > @@ -1543,6 +1543,11 @@ static VhostUserHostNotifier *fetch_or_create_notifier(VhostUserState *u, > > n = g_ptr_array_index(u->notifiers, idx); > if (!n) { > + /* > + * In case notification arrive out-of-order, > + * make room for current index. > + */ > + g_ptr_array_remove_index(u->notifiers, idx); > n = g_new0(VhostUserHostNotifier, 1); > n->idx = idx; > g_ptr_array_insert(u->notifiers, idx, n); Ahh reading the description of g_ptr_array_insert() it doesn't explicitly say it shuffles the data currently at index up but I can see from the code it does. I guess you can imply it from the other function descriptions. Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c index 03415b6c95..d256ce589b 100644 --- a/hw/virtio/vhost-user.c +++ b/hw/virtio/vhost-user.c @@ -1543,6 +1543,11 @@ static VhostUserHostNotifier *fetch_or_create_notifier(VhostUserState *u, n = g_ptr_array_index(u->notifiers, idx); if (!n) { + /* + * In case notification arrive out-of-order, + * make room for current index. + */ + g_ptr_array_remove_index(u->notifiers, idx); n = g_new0(VhostUserHostNotifier, 1); n->idx = idx; g_ptr_array_insert(u->notifiers, idx, n);
vhost backend sends host notification for every VQ. If backend creates VQs in parallel, the VHOST_USER_SLAVE_VRING_HOST_NOTIFIER_MSG may arrive to QEMU in different order than incremental queue index order. For example VQ 1's message arrive earlier than VQ 0's: After alloc VhostUserHostNotifier for VQ 1. GPtrArray becomes [ nil, VQ1 pointer ] After alloc VhostUserHostNotifier for VQ 0. GPtrArray becomes [ VQ0 pointer, nil, VQ1 pointer ] This is wrong. fetch_notifier will return NULL for VQ 1 in vhost_user_get_vring_base, causes host notifier miss removal(leak). The fix is to remove current element from GPtrArray, make the right position for element to insert. Fixes: 503e355465 ("virtio/vhost-user: dynamically assign VhostUserHostNotifiers") Signed-off-by: Yajun Wu <yajunw@nvidia.com> Acked-by: Parav Pandit <parav@nvidia.com> --- hw/virtio/vhost-user.c | 5 +++++ 1 file changed, 5 insertions(+)