Messages in this thread |  | | Date | Sat, 23 Apr 2022 17:41:05 +0800 | Subject | Re: [PATCH 02/13] iommu: Move bus setup to IOMMU device registration | From | Lu Baolu <> |
| |
On 2022/4/23 17:00, Lu Baolu wrote: > On 2022/4/23 16:51, Lu Baolu wrote: >> On 2022/4/23 16:37, Robin Murphy wrote: >>> On 2022-04-23 09:01, Lu Baolu wrote: >>>> Hi Robin, >>>> >>>> On 2022/4/19 15:20, Robin Murphy wrote: >>>>> On 2022-04-19 00:37, Lu Baolu wrote: >>>>>> On 2022/4/19 6:09, Robin Murphy wrote: >>>>>>> On 2022-04-16 01:04, Lu Baolu wrote: >>>>>>>> On 2022/4/14 20:42, Robin Murphy wrote: >>>>>>>>> @@ -1883,27 +1900,12 @@ 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 we still need to keep above lines in bus_set_iommu()? >>>>>>> >>>>>>> It preserves the existing behaviour until each callsite and its >>>>>>> associated error handling are removed later on, which seems like >>>>>>> as good a thing to do as any. Since I'm already relaxing >>>>>>> iommu_device_register() to a warn-but-continue behaviour while it >>>>>>> keeps the bus ops on life-support internally, I figured not >>>>>>> changing too much at once would make it easier to bisect any >>>>>>> potential issues arising from this first step. >>>>>> >>>>>> Fair enough. Thank you for the explanation. >>>>>> >>>>>> Do you have a public tree that I could pull these patches and try >>>>>> them >>>>>> on an Intel hardware? Or perhaps you have done this? I like the whole >>>>>> idea of this series, but it's better to try it with a real hardware. >>>>> >>>>> I haven't bothered with separate branches since there's so many >>>>> different pieces in-flight, but my complete (unstable) development >>>>> branch can be found here: >>>>> >>>>> https://gitlab.arm.com/linux-arm/linux-rm/-/commits/iommu/bus >>>>> >>>>> For now I'd recommend winding the head back to "iommu: Clean up >>>>> bus_set_iommu()" for testing - some of the patches above that have >>>>> already been posted and picked up by their respective subsystems, >>>>> but others are incomplete and barely compile-tested. I'll probably >>>>> rearrange it later this week to better reflect what's happened so far. >>>> >>>> I wound the head back to "iommu: Clean up bus_set_iommu" and tested it >>>> on an Intel machine. It got stuck during boot. This test was on a >>>> remote >>>> machine and I have no means to access it physically. So I can't get any >>>> kernel debugging messages. (I have to work from home these days. :-() >>>> >>>> I guess it's due to the fact that intel_iommu_probe_device() callback >>>> only works for the pci devices. The issue occurs when probing a device >>>> other than a PCI one. >>> >>> Yeah, I was wondering if that would be significant, since it's the >>> only driver that never registered itself for platform_bus_type so >>> won't have actually seen those calls before. I'm inclined to bodge >>> that as below for now, as long as it then works OK in terms of the >>> rest of the changes. >>> >>> Thanks, >>> Robin. >>> >>> ----->8----- >>> diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c >>> index 9fa1b98186a3..6e359f92ec00 100644 >>> --- a/drivers/iommu/intel/iommu.c >>> +++ b/drivers/iommu/intel/iommu.c >>> @@ -4565,6 +4565,10 @@ static struct iommu_device >>> *intel_iommu_probe_device(struct device *dev) >>> unsigned long flags; >>> u8 bus, devfn; >>> >>> + /* ANDD platform device support needs fixing */ >>> + if (!pdev) >>> + return ERR_PTR(-ENODEV); >>> + >>> iommu = device_to_iommu(dev, &bus, &devfn); >>> if (!iommu) >>> return ERR_PTR(-ENODEV); >> >> I haven't seen any real ANDD platform devices, hence this works for me. > > Or more precisely, return NULL when @dev goes through device_to_iommu()? > > diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c > index df5c62ecf942..0d447739e076 100644 > --- a/drivers/iommu/intel/iommu.c > +++ b/drivers/iommu/intel/iommu.c > @@ -797,8 +797,11 @@ struct intel_iommu *device_to_iommu(struct device > *dev, u8 *bus, u8 *devfn) > pf_pdev = pci_physfn(pdev); > dev = &pf_pdev->dev; > segment = pci_domain_nr(pdev->bus); > - } else if (has_acpi_companion(dev)) > + } else if (has_acpi_companion(dev)) { > dev = &ACPI_COMPANION(dev)->dev; > + } else { > + return NULL; > + } > > rcu_read_lock(); > for_each_iommu(iommu, drhd) {
Robin, please ignore this. "has_acpi_companion(dev)" isn't equal to an ANDD device. Please use yours. Sorry for the noise.
Best regards, baolu
|  |