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@xxxxxxxxxxxxxxx wrote:From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx> 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@xxxxxxxxxxxxxxx> --- 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
