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[PATCH 01/11] qdev/qbus: add hidden device support
From: |
Jens Freimann |
Subject: |
[PATCH 01/11] qdev/qbus: add hidden device support |
Date: |
Fri, 18 Oct 2019 22:20:30 +0200 |
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 <address@hidden>
---
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