Re: [PATCH v2 1/1] iommu/vt-d: Fix list_add double add when enabling VMD and scalable mode

[Lu Baolu <baolu.lu@linux.intel.com>]

On 2/18/22 4:21 PM, Huang Adrian wrote:
>> Another thing I am still concerned is about the context entry setup.
>> What does the context entries look like for both VMD and subdevices
>> after domain_context_mapping() being called?
> pasid_table in struct device_domain_info is NULL because the field
> pasid_table is configured in intel_pasid_alloc_table().
> 
> The following statement in domain_context_mapping_one() is true for
> subdevices because the context is configured by the real VMD device
> 0000:59:00.5. So, domain_context_mapping() does nothing for
> subdevices.
>                  if (context_present(context))
>                                goto out_unlock;
> 
> Here is the log for your reference with pr_debug() enabled.
> 
> [   19.063445] pci 0000:59:00.5: Adding to iommu group 42
> ...
> [   22.673502] DMAR: Set context mapping for 59:00.5
> ..
> [   32.089696] vmd 0000:59:00.5: PCI host bridge to bus 10000:80
> [   32.119452] pci 10000:80:01.0: [8086:352a] type 01 class 0x060400
> [   32.126302] pci 10000:80:01.0: reg 0x10: [mem 0x00000000-0x0001ffff 64bit]
> [   32.134023] pci 10000:80:01.0: enabling Extended Tags
> [   32.139730] pci 10000:80:01.0: PME# supported from D0 D3hot D3cold
> [   32.160526] DMAR: Set context mapping for 59:00.5
> [   32.171090] pci 10000:80:01.0: Adding to iommu group 42
> ...

That's clear to me now. Thank you very much!

Best regards,
baolu