This adds support for hiding a device to the qbus and qdev APIs. The first user of this will be the virtio-net failover feature but the API introduced with this patch could be used to implement other features as well, for example hiding pci devices when a pci bus is powered off.
qdev_device_add() is modified to check for a net_failover_pair_id argument in the option string. A DeviceListener callback should_be_hidden() is added. It can be used by a standby device to inform qdev that this device should not be added now. The standby device handler can store the device options to plug the device in at a later point in time. One reason for hiding the device is that we don't want to expose both devices to the guest kernel until the respective virtio feature bit VIRTIO_NET_F_STANDBY was negotiated and we know that the devices will be handled correctly by the guest. More information on the kernel feature this is using: https://www.kernel.org/doc/html/latest/networking/net_failover.html An example where the primary device is a vfio-pci device and the standby device is a virtio-net device: A device is hidden when it has an "net_failover_pair_id" option, e.g. -device virtio-net-pci,...,failover=on,... -device vfio-pci,...,net_failover_pair_id=net1,... Signed-off-by: Jens Freimann <jfreim...@redhat.com> --- hw/core/qdev.c | 23 +++++++++++++++++++++++ include/hw/qdev-core.h | 8 ++++++++ qdev-monitor.c | 36 +++++++++++++++++++++++++++++++++--- vl.c | 6 ++++-- 4 files changed, 68 insertions(+), 5 deletions(-) diff --git a/hw/core/qdev.c b/hw/core/qdev.c index cbad6c1d55..89c134ec53 100644 --- a/hw/core/qdev.c +++ b/hw/core/qdev.c @@ -212,6 +212,29 @@ void device_listener_unregister(DeviceListener *listener) QTAILQ_REMOVE(&device_listeners, listener, link); } +bool qdev_should_hide_device(QemuOpts *opts) +{ + int rc; + DeviceListener *listener; + + QTAILQ_FOREACH(listener, &device_listeners, link) { + if (listener->should_be_hidden) { + /* should_be_hidden_will return + * 1 if device matches opts and it should be hidden + * 0 if device matches opts and should not be hidden + * -1 if device doesn't match ops + */ + rc = listener->should_be_hidden(listener, opts); + } + + if (rc > 0) { + break; + } + } + + return rc > 0; +} + void qdev_set_legacy_instance_id(DeviceState *dev, int alias_id, int required_for_version) { diff --git a/include/hw/qdev-core.h b/include/hw/qdev-core.h index aa123f88cb..28f594a47d 100644 --- a/include/hw/qdev-core.h +++ b/include/hw/qdev-core.h @@ -154,6 +154,12 @@ struct DeviceState { struct DeviceListener { void (*realize)(DeviceListener *listener, DeviceState *dev); void (*unrealize)(DeviceListener *listener, DeviceState *dev); + /* + * This callback is called upon init of the DeviceState and allows to + * inform qdev that a device should be hidden, depending on the device + * opts, for example, to hide a standby device. + */ + int (*should_be_hidden)(DeviceListener *listener, QemuOpts *device_opts); QTAILQ_ENTRY(DeviceListener) link; }; @@ -451,4 +457,6 @@ static inline bool qbus_is_hotpluggable(BusState *bus) void device_listener_register(DeviceListener *listener); void device_listener_unregister(DeviceListener *listener); +bool qdev_should_hide_device(QemuOpts *opts); + #endif diff --git a/qdev-monitor.c b/qdev-monitor.c index 148df9cacf..508d85df87 100644 --- a/qdev-monitor.c +++ b/qdev-monitor.c @@ -32,9 +32,11 @@ #include "qemu/help_option.h" #include "qemu/option.h" #include "qemu/qemu-print.h" +#include "qemu/option_int.h" #include "sysemu/block-backend.h" #include "sysemu/sysemu.h" #include "migration/misc.h" +#include "migration/migration.h" /* * Aliases were a bad idea from the start. Let's keep them @@ -562,14 +564,40 @@ void qdev_set_id(DeviceState *dev, const char *id) } } +static int is_failover_device(void *opaque, const char *name, const char *value, + Error **errp) +{ + if (strcmp(name, "net_failover_pair_id") == 0) { + QemuOpts *opts = (QemuOpts *)opaque; + + if (qdev_should_hide_device(opts)) { + return 1; + } + } + + return 0; +} + +static bool should_hide_device(QemuOpts *opts) +{ + if (qemu_opt_foreach(opts, is_failover_device, opts, NULL) == 0) { + return false; + } + return true; +} + DeviceState *qdev_device_add(QemuOpts *opts, Error **errp) { DeviceClass *dc; const char *driver, *path; - DeviceState *dev; + DeviceState *dev = NULL; BusState *bus = NULL; Error *err = NULL; + if (opts && should_hide_device(opts)) { + return NULL; + } + driver = qemu_opt_get(opts, "driver"); if (!driver) { error_setg(errp, QERR_MISSING_PARAMETER, "driver"); @@ -648,8 +676,10 @@ DeviceState *qdev_device_add(QemuOpts *opts, Error **errp) err_del_dev: error_propagate(errp, err); - object_unparent(OBJECT(dev)); - object_unref(OBJECT(dev)); + if (dev) { + object_unparent(OBJECT(dev)); + object_unref(OBJECT(dev)); + } return NULL; } diff --git a/vl.c b/vl.c index 4489cfb2bb..62c388cb49 100644 --- a/vl.c +++ b/vl.c @@ -2204,10 +2204,12 @@ static int device_init_func(void *opaque, QemuOpts *opts, Error **errp) DeviceState *dev; dev = qdev_device_add(opts, errp); - if (!dev) { + if (!dev && *errp) { + error_report_err(*errp); return -1; + } else if (dev) { + object_unref(OBJECT(dev)); } - object_unref(OBJECT(dev)); return 0; } -- 2.21.0
