Messages in this thread | | | Subject | Re: [PATCH v3 09/14] iommu/arm-smmu: Prevent forced unbinding of Arm SMMU drivers | From | John Garry <> | Date | Tue, 26 Nov 2019 09:13:20 +0000 |
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On 21/11/2019 11:49, Will Deacon wrote: > Forcefully unbinding the Arm SMMU drivers is a pretty dangerous operation, > since it will likely lead to catastrophic failure for any DMA devices > mastering through the SMMU being unbound. When the driver then attempts > to "handle" the fatal faults, it's very easy to trip over dead data > structures, leading to use-after-free. > > On John's machine, he reports that the machine was "unusable" due to > loss of the storage controller following a forced unbind of the SMMUv3 > driver: > > | # cd ./bus/platform/drivers/arm-smmu-v3 > | # echo arm-smmu-v3.0.auto > unbind > | hisi_sas_v2_hw HISI0162:01: CQE_AXI_W_ERR (0x800) found! > | platform arm-smmu-v3.0.auto: CMD_SYNC timeout at 0x00000146 > | [hwprod 0x00000146, hwcons 0x00000000] > > Prevent this forced unbinding of the drivers by setting "suppress_bind_attrs" > to true.
This seems a reasonable approach for now.
BTW, I'll give this series a spin this week, which again looks to be your iommu/module branch, excluding the new IORT patch.
Cheers, John
> > Link: https://lore.kernel.org/lkml/06dfd385-1af0-3106-4cc5-6a5b8e864759@huawei.com > Reported-by: John Garry <john.garry@huawei.com> > Signed-off-by: Will Deacon <will@kernel.org> > --- > drivers/iommu/arm-smmu-v3.c | 5 +++-- > drivers/iommu/arm-smmu.c | 7 ++++--- > 2 files changed, 7 insertions(+), 5 deletions(-) > > diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c > index 2ad8e2ca0583..3fd75abce3bb 100644 > --- a/drivers/iommu/arm-smmu-v3.c > +++ b/drivers/iommu/arm-smmu-v3.c > @@ -3700,8 +3700,9 @@ MODULE_DEVICE_TABLE(of, arm_smmu_of_match); > > static struct platform_driver arm_smmu_driver = { > .driver = { > - .name = "arm-smmu-v3", > - .of_match_table = of_match_ptr(arm_smmu_of_match), > + .name = "arm-smmu-v3", > + .of_match_table = of_match_ptr(arm_smmu_of_match), > + .suppress_bind_attrs = true, > }, > .probe = arm_smmu_device_probe, > .remove = arm_smmu_device_remove, > diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c > index 53bbe0663b9e..d6c83bd69555 100644 > --- a/drivers/iommu/arm-smmu.c > +++ b/drivers/iommu/arm-smmu.c > @@ -2237,9 +2237,10 @@ static const struct dev_pm_ops arm_smmu_pm_ops = { > > static struct platform_driver arm_smmu_driver = { > .driver = { > - .name = "arm-smmu", > - .of_match_table = of_match_ptr(arm_smmu_of_match), > - .pm = &arm_smmu_pm_ops, > + .name = "arm-smmu", > + .of_match_table = of_match_ptr(arm_smmu_of_match), > + .pm = &arm_smmu_pm_ops, > + .suppress_bind_attrs = true, > }, > .probe = arm_smmu_device_probe, > .remove = arm_smmu_device_remove, >
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