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SubjectRe: [PATCH 00/14] iommu: Move iommu_fwspec out of 'struct device'
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On 2020/3/6 18:09, Jean-Philippe Brucker wrote:
> On Fri, Mar 06, 2020 at 04:39:37PM +0800, Hanjun Guo wrote:
>> Hi Joerg,
>>
>> On 2020/2/28 23:08, Joerg Roedel wrote:
>>> Hi,
>>>
>>> here is a patch-set to rename iommu_param to dev_iommu and
>>> establish it as a struct for generic per-device iommu-data.
>>> Also move the iommu_fwspec pointer from struct device into
>>> dev_iommu to have less iommu-related pointers in struct
>>> device.
>>>
>>> The bigger part of this patch-set moves the iommu_priv
>>> pointer from struct iommu_fwspec to dev_iommu, making is
>>> usable for iommu-drivers which do not use fwspecs.
>>>
>>> The changes for that were mostly straightforward, except for
>>> the arm-smmu (_not_ arm-smmu-v3) and the qcom iommu driver.
>>> Unfortunatly I don't have the hardware for those, so any
>>> testing of these drivers is greatly appreciated.
>>
>> I tested this patch set on Kunpeng 920 ARM64 server which
>> using smmu-v3 with ACPI booting, but triggered a NULL
>> pointer dereference and panic at boot:
>
> I think that's because patch 01/14 move the fwspec access too early. In
>
> err = pci_for_each_dma_alias(to_pci_dev(dev),
> iort_pci_iommu_init, &info);
>
> if (!err && iort_pci_rc_supports_ats(node))
> dev->iommu_fwspec->flags |= IOMMU_FWSPEC_PCI_RC_ATS;
>
> the iommu_fwspec is only valid if iort_pci_iommu_init() initialized it
> successfully, if err == 0. The following might fix it:

Good catch :)

>
> diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
> index 0e981d7f3c7d..7d04424189df 100644
> --- a/drivers/acpi/arm64/iort.c
> +++ b/drivers/acpi/arm64/iort.c
> @@ -1015,7 +1015,7 @@ const struct iommu_ops *iort_iommu_configure(struct device *dev)
> return ops;
>
> if (dev_is_pci(dev)) {
> - struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
> + struct iommu_fwspec *fwspec;
> struct pci_bus *bus = to_pci_dev(dev)->bus;
> struct iort_pci_alias_info info = { .dev = dev };
>
> @@ -1028,7 +1028,8 @@ const struct iommu_ops *iort_iommu_configure(struct device *dev)
> err = pci_for_each_dma_alias(to_pci_dev(dev),
> iort_pci_iommu_init, &info);
>
> - if (!err && iort_pci_rc_supports_ats(node))
> + fwspec = dev_iommu_fwspec_get(dev);
> + if (fwspec && iort_pci_rc_supports_ats(node))
> fwspec->flags |= IOMMU_FWSPEC_PCI_RC_ATS;
> } else {
> int i = 0;

And the panic disappeared. Joerg, please feel free to add my Tested-by
for smmu-v3 and IORT ACPI patches with above changes.

>
>
> Note that this use of iommu_fwspec will be removed by the ATS cleanup
> series [1], but this change should work as a temporary fix.

Yes, as your patch set will set the ats_supported flag in the
host bridge level, not per device, nice cleanup.

Thanks
Hanjun

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