> On Apr 21, 2022, at 10:55 AM, Markus Armbruster <arm...@redhat.com> wrote: > > Jagannathan Raman <jag.ra...@oracle.com> writes: > >> Add blocker to prevent hot-unplug of devices > > Why do you need this? I'm not doubting you do, I just want to read your > reasons here :)
Hi Markus, :) The x-vfio-user-server depends on an attached PCIDevice. As long as x-vfio-user-server is used, we don’t want the PCIDevice to be unplugged. This blocker prevents an user from removing PCIDevice while the vfio-user server is in use. > >> >> Signed-off-by: Elena Ufimtseva <elena.ufimts...@oracle.com> >> Signed-off-by: John G Johnson <john.g.john...@oracle.com> >> Signed-off-by: Jagannathan Raman <jag.ra...@oracle.com> I recall receiving a “Reviewed-by” from Stefan previously. I’m very sorry I didn’t add that here. I’ll go over all the patches once again to confirm that the “Reviewed-by” status reflects accurately. >> --- >> include/hw/qdev-core.h | 29 +++++++++++++++++++++++++++++ >> hw/core/qdev.c | 24 ++++++++++++++++++++++++ >> softmmu/qdev-monitor.c | 4 ++++ >> 3 files changed, 57 insertions(+) >> >> diff --git a/include/hw/qdev-core.h b/include/hw/qdev-core.h >> index 92c3d65208..1b9fa25e5c 100644 >> --- a/include/hw/qdev-core.h >> +++ b/include/hw/qdev-core.h >> @@ -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: Adds 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: Removes 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: Confirms 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 >> * >> diff --git a/hw/core/qdev.c b/hw/core/qdev.c >> index 84f3019440..0806d8fcaa 100644 >> --- a/hw/core/qdev.c >> +++ b/hw/core/qdev.c >> @@ -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; >> +} > > This cites the most recently added blocker as reason. Your function > comment covers it: "Returns one of the reasons". Okay. I could change the comment to say that it returns the recently added reason. Thank you! -- Jag > >> + >> 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); >> diff --git a/softmmu/qdev-monitor.c b/softmmu/qdev-monitor.c >> index 12fe60c467..9cfd59d17c 100644 >> --- a/softmmu/qdev-monitor.c >> +++ b/softmmu/qdev-monitor.c >> @@ -898,6 +898,10 @@ 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; >