From f3a8505656935cde32e28c1c6317f725084da1e0 Mon Sep 17 00:00:00 2001 From: Jens Freimann Date: Tue, 29 Oct 2019 12:48:55 +0100 Subject: qdev/qbus: add hidden device support 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 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 "failover_pair_id" option, e.g. -device virtio-net-pci,...,failover=on,... -device vfio-pci,...,failover_pair_id=net1,... Signed-off-by: Jens Freimann Message-Id: <20191029114905.6856-2-jfreimann@redhat.com> Reviewed-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin --- hw/core/qdev.c | 24 ++++++++++++++++++++++++ include/hw/qdev-core.h | 29 +++++++++++++++++++++++++++++ qdev-monitor.c | 41 +++++++++++++++++++++++++++++++++++++---- vl.c | 6 ++++-- 4 files changed, 94 insertions(+), 6 deletions(-) diff --git a/hw/core/qdev.c b/hw/core/qdev.c index cbad6c1d55..3b8d43d0fd 100644 --- a/hw/core/qdev.c +++ b/hw/core/qdev.c @@ -212,6 +212,30 @@ void device_listener_unregister(DeviceListener *listener) QTAILQ_REMOVE(&device_listeners, listener, link); } +bool qdev_should_hide_device(QemuOpts *opts) +{ + int rc = -1; + 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..710981af36 100644 --- a/include/hw/qdev-core.h +++ b/include/hw/qdev-core.h @@ -78,6 +78,19 @@ typedef void (*BusUnrealize)(BusState *bus, Error **errp); * respective parent types. * * + * + * # Hiding a device # + * To hide a device, a DeviceListener function should_be_hidden() needs to + * be registered. + * It can be used to defer adding a device and therefore hide it from the + * guest. The handler registering to this DeviceListener can save the QOpts + * passed to it for re-using it later and must return that it wants the device + * to be/remain hidden or not. When the handler function decides the device + * shall not be hidden it will be added in qdev_device_add() and + * realized as any other device. Otherwise qdev_device_add() will return early + * without adding the device. The guest will not see a "hidden" device + * until it was marked don't hide and qdev_device_add called again. + * */ typedef struct DeviceClass { /*< private >*/ @@ -154,6 +167,12 @@ 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 +470,14 @@ static inline bool qbus_is_hotpluggable(BusState *bus) void device_listener_register(DeviceListener *listener); void device_listener_unregister(DeviceListener *listener); +/** + * @qdev_should_hide_device: + * @opts: QemuOpts as passed on cmdline. + * + * Check if a device should be added. + * When a device is added via qdev_device_add() this will be called, + * and return if the device should be added now or not. + */ +bool qdev_should_hide_device(QemuOpts *opts); + #endif diff --git a/qdev-monitor.c b/qdev-monitor.c index 148df9cacf..ffa08c670f 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 @@ -562,13 +564,36 @@ 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, "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; + bool hide; driver = qemu_opt_get(opts, "driver"); if (!driver) { @@ -602,11 +627,17 @@ DeviceState *qdev_device_add(QemuOpts *opts, Error **errp) return NULL; } } - if (qdev_hotplug && bus && !qbus_is_hotpluggable(bus)) { + hide = should_hide_device(opts); + + if ((hide || qdev_hotplug) && bus && !qbus_is_hotpluggable(bus)) { error_setg(errp, QERR_BUS_NO_HOTPLUG, bus->name); return NULL; } + if (hide) { + return NULL; + } + if (!migration_is_idle()) { error_setg(errp, "device_add not allowed while migrating"); return NULL; @@ -648,8 +679,10 @@ 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 49778e7399..c389d24b2c 100644 --- a/vl.c +++ b/vl.c @@ -2207,10 +2207,12 @@ 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; } -- cgit v1.2.3