Messages in this thread | | | Date | Fri, 29 Apr 2022 09:50:24 +0100 | Subject | Re: [PATCH v2 03/14] iommu: Move bus setup to IOMMU device registration | From | Robin Murphy <> |
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On 2022-04-29 07:57, Baolu Lu wrote: > 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.
Hmm, but probe_iommu_group() is supposed to prevent the __iommu_probe_device() call even happening if the device *has* already been probed before :/
I've still got an old Intel box spare in the office so I'll rig that up and see if I can see what might be going on here...
Thanks, Robin.
> > 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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