Messages in this thread | | | Subject | Re: [PATCH v5 2/7] PCI/ATS: Initialize PRI in pci_ats_init() | From | sathyanarayanan kuppuswamy <> | Date | Mon, 12 Aug 2019 14:35:32 -0700 |
| |
Hi,
Thanks for the review.
On 8/12/19 1:04 PM, Bjorn Helgaas wrote: > On Thu, Aug 01, 2019 at 05:05:59PM -0700, sathyanarayanan.kuppuswamy@linux.intel.com wrote: >> From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com> >> >> Currently, PRI Capability checks are repeated across all PRI API's. >> Instead, cache the capability check result in pci_pri_init() and use it >> in other PRI API's. Also, since PRI is a shared resource between PF/VF, >> initialize default values for common PRI features in pci_pri_init(). > This patch does two things, and it would be better if they were split: > > 1) Cache the PRI capability offset > 2) Separate the PF and VF paths Ok. I will split it into two patches in next version. > >> Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com> >> --- >> drivers/pci/ats.c | 80 ++++++++++++++++++++++++++++------------- >> include/linux/pci-ats.h | 5 +++ >> include/linux/pci.h | 1 + >> 3 files changed, 61 insertions(+), 25 deletions(-) >> >> diff --git a/drivers/pci/ats.c b/drivers/pci/ats.c >> index cdd936d10f68..280be911f190 100644 >> --- a/drivers/pci/ats.c >> +++ b/drivers/pci/ats.c >> @@ -28,6 +28,8 @@ void pci_ats_init(struct pci_dev *dev) >> return; >> >> dev->ats_cap = pos; >> + >> + pci_pri_init(dev); >> } >> >> /** >> @@ -170,36 +172,72 @@ int pci_ats_page_aligned(struct pci_dev *pdev) >> EXPORT_SYMBOL_GPL(pci_ats_page_aligned); >> >> #ifdef CONFIG_PCI_PRI >> + >> +void pci_pri_init(struct pci_dev *pdev) >> +{ >> + u32 max_requests; >> + int pos; >> + >> + /* >> + * As per PCIe r4.0, sec 9.3.7.11, only PF is permitted to >> + * implement PRI and all associated VFs can only use it. >> + * Since PF already initialized the PRI parameters there is >> + * no need to proceed further. >> + */ >> + if (pdev->is_virtfn) >> + return; >> + >> + pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PRI); >> + if (!pos) >> + return; >> + >> + pci_read_config_dword(pdev, pos + PCI_PRI_MAX_REQ, &max_requests); >> + >> + /* >> + * Since PRI is a shared resource between PF and VF, we must not >> + * configure Outstanding Page Allocation Quota as a per device >> + * resource in pci_enable_pri(). So use maximum value possible >> + * as default value. >> + */ >> + pci_write_config_dword(pdev, pos + PCI_PRI_ALLOC_REQ, max_requests); >> + >> + pdev->pri_reqs_alloc = max_requests; >> + pdev->pri_cap = pos; >> +} >> + >> /** >> * pci_enable_pri - Enable PRI capability >> * @ pdev: PCI device structure >> * >> * Returns 0 on success, negative value on error >> + * >> + * TODO: Since PRI is a shared resource between PF/VF, don't update >> + * Outstanding Page Allocation Quota in the same API as a per device >> + * feature. >> */ >> int pci_enable_pri(struct pci_dev *pdev, u32 reqs) >> { >> u16 control, status; >> u32 max_requests; >> - int pos; >> >> if (WARN_ON(pdev->pri_enabled)) >> return -EBUSY; >> >> - pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PRI); >> - if (!pos) >> + if (!pdev->pri_cap) >> return -EINVAL; >> >> - pci_read_config_word(pdev, pos + PCI_PRI_STATUS, &status); >> + pci_read_config_word(pdev, pdev->pri_cap + PCI_PRI_STATUS, &status); >> if (!(status & PCI_PRI_STATUS_STOPPED)) >> return -EBUSY; >> >> - pci_read_config_dword(pdev, pos + PCI_PRI_MAX_REQ, &max_requests); >> + pci_read_config_dword(pdev, pdev->pri_cap + PCI_PRI_MAX_REQ, >> + &max_requests); >> reqs = min(max_requests, reqs); >> pdev->pri_reqs_alloc = reqs; >> - pci_write_config_dword(pdev, pos + PCI_PRI_ALLOC_REQ, reqs); >> + pci_write_config_dword(pdev, pdev->pri_cap + PCI_PRI_ALLOC_REQ, reqs); > The comment above says "don't update Outstanding Page Allocation > Quota" but it looks like that's what this is doing.
I don't want to fix it in the current patch-set. It needs further scrutiny. That's why I have added the TODO comment for it.
Currently, intel-iommu and amd-iommu drivers (only users of pci_enable_pri()) hard-codes 32 as a default value for Outstanding Page Allocation Quota. Only exception is, amd-iommu sets this value as 1 for devices with erratum AMD_PRI_DEV_ERRATUM_LIMIT_REQ_ONE. There is no comment or spec reference that explains why 32 is chosen as default value. Also configuring 32 as per device max value will break for PF/VF devices since they share the PRI interface. So without clear history, I don't want to make any changes which might affect their functionality.
IMO, the correct way is to configure the Outstanding Page Allocation Quota with maximum value in pci_pri_init(). So, even if IOMMU can't handle more than 32 page request per device, it can fail properly and it should not affect the functionality.
I have added proper configuration for Outstanding Page Allocation Quota in pci_pri_init(), but it does not serve any purpose until we fix the part of the issue in pci_enable_pri(). If you want, I can remove it for now, and add it when fixing the issue in pci_enable_pri(). > >> control = PCI_PRI_CTRL_ENABLE; >> - pci_write_config_word(pdev, pos + PCI_PRI_CTRL, control); >> + pci_write_config_word(pdev, pdev->pri_cap + PCI_PRI_CTRL, control); >> >> pdev->pri_enabled = 1; >> >> @@ -216,18 +254,16 @@ EXPORT_SYMBOL_GPL(pci_enable_pri); >> void pci_disable_pri(struct pci_dev *pdev) >> { >> u16 control; >> - int pos; >> >> if (WARN_ON(!pdev->pri_enabled)) >> return; >> >> - pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PRI); >> - if (!pos) >> + if (!pdev->pri_cap) >> return; >> >> - pci_read_config_word(pdev, pos + PCI_PRI_CTRL, &control); >> + pci_read_config_word(pdev, pdev->pri_cap + PCI_PRI_CTRL, &control); >> control &= ~PCI_PRI_CTRL_ENABLE; >> - pci_write_config_word(pdev, pos + PCI_PRI_CTRL, control); >> + pci_write_config_word(pdev, pdev->pri_cap + PCI_PRI_CTRL, control); >> >> pdev->pri_enabled = 0; >> } >> @@ -241,17 +277,15 @@ void pci_restore_pri_state(struct pci_dev *pdev) >> { >> u16 control = PCI_PRI_CTRL_ENABLE; >> u32 reqs = pdev->pri_reqs_alloc; >> - int pos; >> >> if (!pdev->pri_enabled) >> return; >> >> - pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PRI); >> - if (!pos) >> + if (!pdev->pri_cap) >> return; >> >> - pci_write_config_dword(pdev, pos + PCI_PRI_ALLOC_REQ, reqs); >> - pci_write_config_word(pdev, pos + PCI_PRI_CTRL, control); >> + pci_write_config_dword(pdev, pdev->pri_cap + PCI_PRI_ALLOC_REQ, reqs); >> + pci_write_config_word(pdev, pdev->pri_cap + PCI_PRI_CTRL, control); >> } >> EXPORT_SYMBOL_GPL(pci_restore_pri_state); >> >> @@ -265,17 +299,15 @@ EXPORT_SYMBOL_GPL(pci_restore_pri_state); >> int pci_reset_pri(struct pci_dev *pdev) >> { >> u16 control; >> - int pos; >> >> if (WARN_ON(pdev->pri_enabled)) >> return -EBUSY; >> >> - pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PRI); >> - if (!pos) >> + if (!pdev->pri_cap) >> return -EINVAL; >> >> control = PCI_PRI_CTRL_RESET; >> - pci_write_config_word(pdev, pos + PCI_PRI_CTRL, control); >> + pci_write_config_word(pdev, pdev->pri_cap + PCI_PRI_CTRL, control); >> >> return 0; >> } >> @@ -410,13 +442,11 @@ EXPORT_SYMBOL_GPL(pci_pasid_features); >> int pci_prg_resp_pasid_required(struct pci_dev *pdev) >> { >> u16 status; >> - int pos; >> >> - pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PRI); >> - if (!pos) >> + if (!pdev->pri_cap) >> return 0; >> >> - pci_read_config_word(pdev, pos + PCI_PRI_STATUS, &status); >> + pci_read_config_word(pdev, pdev->pri_cap + PCI_PRI_STATUS, &status); >> >> if (status & PCI_PRI_STATUS_PASID) >> return 1; >> diff --git a/include/linux/pci-ats.h b/include/linux/pci-ats.h >> index 1a0bdaee2f32..33653d4ca94f 100644 >> --- a/include/linux/pci-ats.h >> +++ b/include/linux/pci-ats.h >> @@ -6,6 +6,7 @@ >> >> #ifdef CONFIG_PCI_PRI >> >> +void pci_pri_init(struct pci_dev *pdev); > I think this could be moved to drivers/pci/pci.h, since it doesn't > need to be visible outside drivers/pci/. Makes sense. I will move it. > >> int pci_enable_pri(struct pci_dev *pdev, u32 reqs); >> void pci_disable_pri(struct pci_dev *pdev); >> void pci_restore_pri_state(struct pci_dev *pdev); >> @@ -13,6 +14,10 @@ int pci_reset_pri(struct pci_dev *pdev); >> >> #else /* CONFIG_PCI_PRI */ >> >> +static inline void pci_pri_init(struct pci_dev *pdev) >> +{ >> +} >> + >> static inline int pci_enable_pri(struct pci_dev *pdev, u32 reqs) >> { >> return -ENODEV; >> diff --git a/include/linux/pci.h b/include/linux/pci.h >> index 9e700d9f9f28..56b55db099fc 100644 >> --- a/include/linux/pci.h >> +++ b/include/linux/pci.h >> @@ -455,6 +455,7 @@ struct pci_dev { >> atomic_t ats_ref_cnt; /* Number of VFs with ATS enabled */ >> #endif >> #ifdef CONFIG_PCI_PRI >> + u16 pri_cap; /* PRI Capability offset */ >> u32 pri_reqs_alloc; /* Number of PRI requests allocated */ >> #endif >> #ifdef CONFIG_PCI_PASID >> -- >> 2.21.0 >> -- Sathyanarayanan Kuppuswamy Linux kernel developer
| |