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qdev: unplug blocker for devices

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Add blocker to prevent hot-unplug of devices

TYPE_VFIO_USER_SERVER, which is introduced shortly, attaches itself to a
PCIDevice on which it depends. If the attached PCIDevice gets removed
while the server in use, it could cause it crash. To prevent this,
TYPE_VFIO_USER_SERVER adds an unplug blocker for the PCIDevice.

Signed-off-by: Elena Ufimtseva <elena.ufimtseva@oracle.com>
Signed-off-by: John G Johnson <john.g.johnson@oracle.com>
Signed-off-by: Jagannathan Raman <jag.raman@oracle.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: c41ef80b7cc063314d629737bed2159e5713f2e0.1655151679.git.jag.raman@oracle.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Jagannathan Raman 2022-06-13 16:26:21 -04:00 committed by Stefan Hajnoczi
parent e2848bc574
commit 217c7f01ad
3 changed files with 57 additions and 0 deletions
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24
hw/core/qdev.c
View file

@ -468,6 +468,28 @@ char *qdev_get_dev_path(DeviceState *dev)
return NULL;
}
void qdev_add_unplug_blocker(DeviceState *dev, Error *reason)
{
dev->unplug_blockers = g_slist_prepend(dev->unplug_blockers, reason);
}
void qdev_del_unplug_blocker(DeviceState *dev, Error *reason)
{
dev->unplug_blockers = g_slist_remove(dev->unplug_blockers, reason);
}
bool qdev_unplug_blocked(DeviceState *dev, Error **errp)
{
ERRP_GUARD();
if (dev->unplug_blockers) {
error_propagate(errp, error_copy(dev->unplug_blockers->data));
return true;
}
return false;
}
static bool device_get_realized(Object *obj, Error **errp)
{
DeviceState *dev = DEVICE(obj);
@ -704,6 +726,8 @@ static void device_finalize(Object *obj)
DeviceState *dev = DEVICE(obj);
g_assert(!dev->unplug_blockers);
QLIST_FOREACH_SAFE(ngl, &dev->gpios, node, next) {
QLIST_REMOVE(ngl, node);
qemu_free_irqs(ngl->in, ngl->num_in);

29
include/hw/qdev-core.h
View file

@ -193,6 +193,7 @@ struct DeviceState {
int instance_id_alias;
int alias_required_for_version;
ResettableState reset;
GSList *unplug_blockers;
};
struct DeviceListener {
@ -419,6 +420,34 @@ void qdev_simple_device_unplug_cb(HotplugHandler *hotplug_dev,
void qdev_machine_creation_done(void);
bool qdev_machine_modified(void);
/**
* qdev_add_unplug_blocker: Add an unplug blocker to a device
*
* @dev: Device to be blocked from unplug
* @reason: Reason for blocking
*/
void qdev_add_unplug_blocker(DeviceState *dev, Error *reason);
/**
* qdev_del_unplug_blocker: Remove an unplug blocker from a device
*
* @dev: Device to be unblocked
* @reason: Pointer to the Error used with qdev_add_unplug_blocker.
* Used as a handle to lookup the blocker for deletion.
*/
void qdev_del_unplug_blocker(DeviceState *dev, Error *reason);
/**
* qdev_unplug_blocked: Confirm if a device is blocked from unplug
*
* @dev: Device to be tested
* @reason: Returns one of the reasons why the device is blocked,
* if any
*
* Returns: true if device is blocked from unplug, false otherwise
*/
bool qdev_unplug_blocked(DeviceState *dev, Error **errp);
/**
* GpioPolarity: Polarity of a GPIO line
*

4
softmmu/qdev-monitor.c
View file

@ -899,6 +899,10 @@ void qdev_unplug(DeviceState *dev, Error **errp)
HotplugHandlerClass *hdc;
Error *local_err = NULL;
if (qdev_unplug_blocked(dev, errp)) {
return;
}
if (dev->parent_bus && !qbus_is_hotpluggable(dev->parent_bus)) {
error_setg(errp, QERR_BUS_NO_HOTPLUG, dev->parent_bus->name);
return;