| Message ID | 20191018202040.30349-2-jfreimann@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | add failover feature for assigned network devices | expand |
On Fri, 18 Oct 2019 22:20:30 +0200 Jens Freimann <jfreimann@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 <jfreimann@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; Initialize to 0? > + 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) > { (...) > +static bool should_hide_device(QemuOpts *opts) > +{ > + if (qemu_opt_foreach(opts, is_failover_device, opts, NULL) == 0) { > + return false; > + } > + return true; > +} I still think you should turn the check around to make it easier to extend in the future, but this is fine as well. (...) With the rc thing changed, Reviewed-by: Cornelia Huck <cohuck@redhat.com>
On Mon, Oct 21, 2019 at 02:44:08PM +0200, Cornelia Huck wrote: >On Fri, 18 Oct 2019 22:20:30 +0200 >Jens Freimann <jfreimann@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 <jfreimann@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; > >Initialize to 0? Yes, that's what the test bot found as well. Fixed it already. Though I initialize to -1, otherwise all devices will be hidden. >> + 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) >> { > >(...) > >> +static bool should_hide_device(QemuOpts *opts) >> +{ >> + if (qemu_opt_foreach(opts, is_failover_device, opts, NULL) == 0) { >> + return false; >> + } >> + return true; >> +} > >I still think you should turn the check around to make it easier to >extend in the future, but this is fine as well. Sorry, I've gone back and forth on this and ended up with the same. I'll take another look at it. >(...) > >With the rc thing changed, > >Reviewed-by: Cornelia Huck <cohuck@redhat.com> Thanks! regards, Jens
On Fri, 18 Oct 2019 at 21:22, Jens Freimann <jfreimann@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. In what sense is a hidden device hidden? Is it hidden from the guest (in what way) ? Is it hidden from the QMP/HMP monitor commands? Is it hidden from QEMU functions that iterate through the qbus, or that walk the QOM tree ? What does a hidden device have to do to be successfully hidden ? Is it completely disconnected from the rest of the simulation, or does it itself have to avoid doing things like asserting IRQ lines ? Expanding the DeviceClass doc comment might be a good place to answer questions like the above and generally describe the 'hidden device' mechanism. > }; > > @@ -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); New globally visible functions should always have doc-comment format documentation comments, please. thanks -- PMM
On Mon, Oct 21, 2019 at 01:53:58PM +0100, Peter Maydell wrote: >On Fri, 18 Oct 2019 at 21:22, Jens Freimann <jfreimann@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. > >In what sense is a hidden device hidden? Is it hidden from >the guest (in what way) ? Is it hidden from the QMP/HMP monitor >commands? Is it hidden from QEMU functions that iterate through >the qbus, or that walk the QOM tree ? What does a hidden device >have to do to be successfully hidden ? Is it completely disconnected >from the rest of the simulation, or does it itself have to avoid >doing things like asserting IRQ lines ? > >Expanding the DeviceClass doc comment might be a good place to answer >questions like the above and generally describe the 'hidden device' >mechanism. ok, I will add to the DeviceClass comment. > >> }; >> >> @@ -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); > >New globally visible functions should always have doc-comment >format documentation comments, please. Will add this too. Thanks for the review! regards, Jens
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; }
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 <jfreimann@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(-)