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SubjectRe: [PATCH v7 1/7] PCI/ATS: Fix pci_prg_resp_pasid_required() dependency issues
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Hi Bjorn,

Thanks for looking into this patch set.

On 9/5/19 12:18 PM, Bjorn Helgaas wrote:
> On Wed, Aug 28, 2019 at 03:14:01PM -0700, sathyanarayanan.kuppuswamy@linux.intel.com wrote:
>> From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
>>
>> Since pci_prg_resp_pasid_required() function has dependency on both
>> PASID and PRI, define it only if both CONFIG_PCI_PRI and
>> CONFIG_PCI_PASID config options are enabled.
>>
>> Fixes: e5567f5f6762 ("PCI/ATS: Add pci_prg_resp_pasid_required()
>> interface.")
> [Don't split tags, including "Fixes:" across lines]
>
> This definitely doesn't fix e5567f5f6762. That commit added
> pci_prg_resp_pasid_required(), but with no dependency on
> CONFIG_PCI_PRI or CONFIG_PCI_PASID.
>
> This patch is only required when a subsequent patch is applied. It
> should be squashed into the commit that requires it so it's obvious
> why it's needed.
>
> I've been poking at this series, and I'll post a v8 soon with this and
> other fixes.
In your v8 submission you did not merge this patch. You did not use
pri_cap or pasid_cap cached values. Instead you have re-read the
value from register. Is this intentional?

Since this function will be called for every VF device we might loose
some performance benefit.

>
>> Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
>> ---
>> drivers/pci/ats.c | 10 ++++++----
>> include/linux/pci-ats.h | 12 +++++++++---
>> 2 files changed, 15 insertions(+), 7 deletions(-)
>>
>> diff --git a/drivers/pci/ats.c b/drivers/pci/ats.c
>> index e18499243f84..cdd936d10f68 100644
>> --- a/drivers/pci/ats.c
>> +++ b/drivers/pci/ats.c
>> @@ -395,6 +395,8 @@ int pci_pasid_features(struct pci_dev *pdev)
>> }
>> EXPORT_SYMBOL_GPL(pci_pasid_features);
>>
>> +#ifdef CONFIG_PCI_PRI
>> +
>> /**
>> * pci_prg_resp_pasid_required - Return PRG Response PASID Required bit
>> * status.
>> @@ -402,10 +404,8 @@ EXPORT_SYMBOL_GPL(pci_pasid_features);
>> *
>> * Returns 1 if PASID is required in PRG Response Message, 0 otherwise.
>> *
>> - * Even though the PRG response PASID status is read from PRI Status
>> - * Register, since this API will mainly be used by PASID users, this
>> - * function is defined within #ifdef CONFIG_PCI_PASID instead of
>> - * CONFIG_PCI_PRI.
>> + * Since this API has dependency on both PRI and PASID, protect it
>> + * with both CONFIG_PCI_PRI and CONFIG_PCI_PASID.
>> */
>> int pci_prg_resp_pasid_required(struct pci_dev *pdev)
>> {
>> @@ -425,6 +425,8 @@ int pci_prg_resp_pasid_required(struct pci_dev *pdev)
>> }
>> EXPORT_SYMBOL_GPL(pci_prg_resp_pasid_required);
>>
>> +#endif
>> +
>> #define PASID_NUMBER_SHIFT 8
>> #define PASID_NUMBER_MASK (0x1f << PASID_NUMBER_SHIFT)
>> /**
>> diff --git a/include/linux/pci-ats.h b/include/linux/pci-ats.h
>> index 1ebb88e7c184..1a0bdaee2f32 100644
>> --- a/include/linux/pci-ats.h
>> +++ b/include/linux/pci-ats.h
>> @@ -40,7 +40,6 @@ void pci_disable_pasid(struct pci_dev *pdev);
>> void pci_restore_pasid_state(struct pci_dev *pdev);
>> int pci_pasid_features(struct pci_dev *pdev);
>> int pci_max_pasids(struct pci_dev *pdev);
>> -int pci_prg_resp_pasid_required(struct pci_dev *pdev);
>>
>> #else /* CONFIG_PCI_PASID */
>>
>> @@ -67,11 +66,18 @@ static inline int pci_max_pasids(struct pci_dev *pdev)
>> return -EINVAL;
>> }
>>
>> +#endif /* CONFIG_PCI_PASID */
>> +
>> +#if defined(CONFIG_PCI_PRI) && defined(CONFIG_PCI_PASID)
>> +
>> +int pci_prg_resp_pasid_required(struct pci_dev *pdev);
>> +
>> +#else /* CONFIG_PCI_PASID && CONFIG_PCI_PRI */
>> +
>> static inline int pci_prg_resp_pasid_required(struct pci_dev *pdev)
>> {
>> return 0;
>> }
>> -#endif /* CONFIG_PCI_PASID */
>> -
>> +#endif
>>
>> #endif /* LINUX_PCI_ATS_H*/
>> --
>> 2.21.0
>>
--
Sathyanarayanan Kuppuswamy
Linux kernel developer

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