Messages in this thread | | | Date | Fri, 29 Apr 2022 14:57:46 +0800 | Subject | Re: [PATCH v2 03/14] iommu: Move bus setup to IOMMU device registration | From | Baolu Lu <> |
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Hi Robin,
On 2022/4/28 21:18, Robin Murphy wrote: > Move the bus setup to iommu_device_register(). This should allow > bus_iommu_probe() to be correctly replayed for multiple IOMMU instances, > and leaves bus_set_iommu() as a glorified no-op to be cleaned up next.
I re-fetched the latest patches on
https://gitlab.arm.com/linux-arm/linux-rm/-/commits/iommu/bus
and rolled back the head to "iommu: Cleanup bus_set_iommu".
The test machine still hangs during boot.
I went through the code. It seems that the .probe_device for Intel IOMMU driver can't handle the probe replay well. It always assumes that the device has never been probed.
Best regards, baolu
> > At this point we can also handle cleanup better than just rolling back > the most-recently-touched bus upon failure - which may release devices > owned by other already-registered instances, and still leave devices on > other buses with dangling pointers to the failed instance. Now it's easy > to clean up the exact footprint of a given instance, no more, no less. > > Tested-by: Marek Szyprowski <m.szyprowski@samsung.com> > Signed-off-by: Robin Murphy <robin.murphy@arm.com> > --- > drivers/iommu/iommu.c | 51 +++++++++++++++++++++++-------------------- > 1 file changed, 27 insertions(+), 24 deletions(-) > > diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c > index 6c4621afc8cf..c89af4dc54c2 100644 > --- a/drivers/iommu/iommu.c > +++ b/drivers/iommu/iommu.c > @@ -175,6 +175,14 @@ static int __init iommu_subsys_init(void) > } > subsys_initcall(iommu_subsys_init); > > +static int remove_iommu_group(struct device *dev, void *data) > +{ > + if (dev->iommu && dev->iommu->iommu_dev == data) > + iommu_release_device(dev); > + > + return 0; > +} > + > /** > * iommu_device_register() - Register an IOMMU hardware instance > * @iommu: IOMMU handle for the instance > @@ -197,12 +205,29 @@ int iommu_device_register(struct iommu_device *iommu, > spin_lock(&iommu_device_lock); > list_add_tail(&iommu->list, &iommu_device_list); > spin_unlock(&iommu_device_lock); > + > + for (int i = 0; i < ARRAY_SIZE(iommu_buses); i++) { > + struct bus_type *bus = iommu_buses[i]; > + int err; > + > + WARN_ON(bus->iommu_ops && bus->iommu_ops != ops); > + bus->iommu_ops = ops; > + err = bus_iommu_probe(bus); > + if (err) { > + iommu_device_unregister(iommu); > + return err; > + } > + } > + > return 0; > } > EXPORT_SYMBOL_GPL(iommu_device_register); > > void iommu_device_unregister(struct iommu_device *iommu) > { > + for (int i = 0; i < ARRAY_SIZE(iommu_buses); i++) > + bus_for_each_dev(iommu_buses[i], NULL, iommu, remove_iommu_group); > + > spin_lock(&iommu_device_lock); > list_del(&iommu->list); > spin_unlock(&iommu_device_lock); > @@ -1655,13 +1680,6 @@ static int probe_iommu_group(struct device *dev, void *data) > return ret; > } > > -static int remove_iommu_group(struct device *dev, void *data) > -{ > - iommu_release_device(dev); > - > - return 0; > -} > - > static int iommu_bus_notifier(struct notifier_block *nb, > unsigned long action, void *data) > { > @@ -1884,27 +1902,12 @@ static int iommu_bus_init(struct bus_type *bus) > */ > int bus_set_iommu(struct bus_type *bus, const struct iommu_ops *ops) > { > - int err; > - > - if (ops == NULL) { > - bus->iommu_ops = NULL; > - return 0; > - } > - > - if (bus->iommu_ops != NULL) > + if (bus->iommu_ops && ops && bus->iommu_ops != ops) > return -EBUSY; > > bus->iommu_ops = ops; > > - /* Do IOMMU specific setup for this bus-type */ > - err = bus_iommu_probe(bus); > - if (err) { > - /* Clean up */ > - bus_for_each_dev(bus, NULL, NULL, remove_iommu_group); > - bus->iommu_ops = NULL; > - } > - > - return err; > + return 0; > } > EXPORT_SYMBOL_GPL(bus_set_iommu); >
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