On Fri, 11 Oct 2019 13:20:06 +0200 Jens Freimann <jfreim...@redhat.com> wrote:
> 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 | 19 +++++++++++++++++++ > include/hw/qdev-core.h | 9 +++++++++ > qdev-monitor.c | 43 ++++++++++++++++++++++++++++++++++++++---- > vl.c | 6 ++++-- > 4 files changed, 71 insertions(+), 6 deletions(-) > > diff --git a/hw/core/qdev.c b/hw/core/qdev.c > index cbad6c1d55..84fac591ca 100644 > --- a/hw/core/qdev.c > +++ b/hw/core/qdev.c > @@ -212,6 +212,25 @@ void device_listener_unregister(DeviceListener *listener) > QTAILQ_REMOVE(&device_listeners, listener, link); > } > > +bool qdev_should_hide_device(QemuOpts *opts, Error **errp) > +{ > + bool res = false; > + bool match_found = false; > + DeviceListener *listener; > + > + QTAILQ_FOREACH(listener, &device_listeners, link) { > + if (listener->should_be_hidden) { > + listener->should_be_hidden(listener, opts, &match_found, &res); > + } > + > + if (match_found) { > + break; > + } Calling convention here seems overly complicated, couldn't should_be_hidden() just return >0 (should be hidden), 0 (should not be hidden), <0 (don't care), ie. continue until >=0? The errp arg is unused and using "res" to return should/shouldn't hide is very unclear. The virtio callback renames this to hide, which makes more sense, but as above, both the stop and hidden state could be conveyed with a simple int return value. Thanks, Alex > + } > + > + return res; > +} > + > 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..b61cf82ded 100644 > --- a/include/hw/qdev-core.h > +++ b/include/hw/qdev-core.h > @@ -154,6 +154,13 @@ struct DeviceState { > struct DeviceListener { > void (*realize)(DeviceListener *listener, DeviceState *dev); > void (*unrealize)(DeviceListener *listener, DeviceState *dev); > + /* > + * This callback is called just upon init of the DeviceState > + * and can be used by a standby device for informing qdev if this > + * device should be hidden by checking the device opts > + */ > + void (*should_be_hidden)(DeviceListener *listener, QemuOpts *device_opts, > + bool *match_found, bool *res); > QTAILQ_ENTRY(DeviceListener) link; > }; > > @@ -451,4 +458,6 @@ 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, Error **errp); > + > #endif > diff --git a/qdev-monitor.c b/qdev-monitor.c > index 148df9cacf..9fc8331157 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 +564,45 @@ 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, errp) && errp && !*errp) { > + return 1; > + } else if (errp && *errp) { > + return -1; > + } > + } > + > + return 0; > +} > + > +static bool should_hide_device(QemuOpts *opts, Error **err) > +{ > + if (qemu_opt_foreach(opts, is_failover_device, opts, err) == 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, &err)) { > + if (err) { > + goto err_del_dev; > + } > + return NULL; > + } > + > driver = qemu_opt_get(opts, "driver"); > if (!driver) { > error_setg(errp, QERR_MISSING_PARAMETER, "driver"); > @@ -648,8 +681,10 @@ 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; > } > > @@ -818,7 +853,7 @@ void qdev_unplug(DeviceState *dev, Error **errp) > return; > } > > - if (!migration_is_idle()) { > + if (!migration_is_idle() && !migration_in_setup(migrate_get_current())) { > error_setg(errp, "device_del not allowed while migrating"); > return; > } > diff --git a/vl.c b/vl.c > index 002bf4919e..898b9901c8 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; > } >
