[PATCH v2 9/9] iommu/vt-d: Use pci core's DVSEC functionality

[Lu Baolu]

Hi Dan,

On 9/29/21 1:54 AM, Dan Williams wrote:
> On Thu, Sep 23, 2021 at 10:27 AM Ben Widawsky <ben.widawsky at intel.com> wrote:
>>
>> Reduce maintenance burden of DVSEC query implementation by using the
>> centralized PCI core implementation.
>>
>> Cc: iommu at lists.linux-foundation.org
>> Cc: David Woodhouse <dwmw2 at infradead.org>
>> Cc: Lu Baolu <baolu.lu at linux.intel.com>
>> Signed-off-by: Ben Widawsky <ben.widawsky at intel.com>
>> ---
>>   drivers/iommu/intel/iommu.c | 15 +--------------
>>   1 file changed, 1 insertion(+), 14 deletions(-)
>>
>> diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
>> index d75f59ae28e6..30c97181f0ae 100644
>> --- a/drivers/iommu/intel/iommu.c
>> +++ b/drivers/iommu/intel/iommu.c
>> @@ -5398,20 +5398,7 @@ static int intel_iommu_disable_sva(struct device *dev)
>>    */
>>   static int siov_find_pci_dvsec(struct pci_dev *pdev)
>>   {
>> -       int pos;
>> -       u16 vendor, id;
>> -
>> -       pos = pci_find_next_ext_capability(pdev, 0, 0x23);
>> -       while (pos) {
>> -               pci_read_config_word(pdev, pos + 4, &vendor);
>> -               pci_read_config_word(pdev, pos + 8, &id);
>> -               if (vendor == PCI_VENDOR_ID_INTEL && id == 5)
>> -                       return pos;
>> -
>> -               pos = pci_find_next_ext_capability(pdev, pos, 0x23);
>> -       }
>> -
>> -       return 0;
>> +       return pci_find_dvsec_capability(pdev, PCI_VENDOR_ID_INTEL, 5);
>>   }
> 
> Same comments as the CXL patch, siov_find_pci_dvsec() doesn't seem to
> have a reason to exist anymore. What is 5?

"5" is DVSEC ID for Scalable IOV.

Anyway, the siov_find_pci_dvsec() has been dead code since commit
262948f8ba57 ("iommu: Delete iommu_dev_has_feature()"). I have a patch
to clean it up. No need to care about it in this series.

Best regards,
baolu