On Mon, Oct 14, 2019 at 11:46:22AM +0200, Cornelia Huck wrote:
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/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
+ */
Maybe tweak this comment a bit:
/*
* 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.
*/
This makes it clearer that this interface could be reused for other
purposes.
Sounds good.
+ 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;
Maybe turn that check around? I.e. return true if the failover property
is present, else return false. Makes it easier to add checks for other
properties in the future.
Done.
+ }
+ 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())) {
Hm, should that hunk go into another patch?
Yes it should :)
Thanks for the review!
regards,
Jens
