Messages in this thread Patch in this message | | | Subject | Re: [PATCH v3 1/7] PCI/ATS: Fix pci_prg_resp_pasid_required() dependency issues | From | sathyanarayanan kuppuswamy <> | Date | Wed, 3 Jul 2019 11:23:37 -0700 |
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Hi,
On 7/3/19 10:56 AM, Bjorn Helgaas wrote: > On Thu, Jun 20, 2019 at 01:38:42PM -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. > This is likely just confusion on my part, but I don't understand what > you're doing here. > > pci_prg_resp_pasid_required() does not actually *depend* on the > CONFIG_PCI_PRI config symbol.
pci_prg_resp_pasid_required() function internally reads the PRI status register to get the status of PASID required bit.
FILE:drivers/pci/ats.c
419 pci_read_config_word(pdev, pos + PCI_PRI_STATUS, &status); 420 421 if (status & PCI_PRI_STATUS_PASID)
Since pci_prg_resp_pasid_required() function is only used if CONFIG_PCI_PASID is enabled, and since it also has internal PCI_PRI dependency, I have protected it with both CONFIG_PCI_PASID and CONFIG_PCI_PRI ifdefs.
> > It is currently compiled only if CONFIG_PCI_ATS=y (which controls > compilation of the entire ats.c) and CONFIG_PCI_PASID=y (since it's > within #ifdef CONFIG_PCI_PASID). > > pci_prg_resp_pasid_required() is called by attach_device() > (amd_iommu.c), which is only compiled if CONFIG_AMD_IOMMU=y, and that > selects PCI_PRI. pci_prg_resp_pasid_required() is also called by intel_iommu.c, and enabling CONFIG_INTEL_IOMMU does not enable PCI_PRI/PCI_PASID by default. > > It is also called by iommu_enable_dev_iotlb() (intel-iommu.c). That > file is compiled if CONFIG_INTEL_IOMMU=y and the call itself is inside > #ifdef CONFIG_INTEL_IOMMU_SVM. But I don't see the PCI_PRI connection > here. > > If this is just to limit the visibility, say that. But I don't think > that's really a good reason. The chain of config symbols seems a > little too complicated. > >> Fixes: e5567f5f6762 ("PCI/ATS: Add pci_prg_resp_pasid_required() >> interface.") >> 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 97c08146534a..f9eeb7db0db3 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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