From: sathyanarayanan kuppuswamy <sathyanarayanan.kuppuswamy@linux.intel.com> To: Bjorn Helgaas <helgaas@kernel.org> Cc: linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, ashok.raj@intel.com, keith.busch@intel.com Subject: Re: [PATCH v5 4/7] PCI/ATS: Add PRI support for PCIe VF devices Date: Mon, 12 Aug 2019 14:40:31 -0700 Message-ID: <f6ee630d-6db5-a39e-6660-6c96a27189b4@linux.intel.com> (raw) In-Reply-To: <20190812200456.GL11785@google.com> Hi, On 8/12/19 1:04 PM, Bjorn Helgaas wrote: > On Thu, Aug 01, 2019 at 05:06:01PM -0700, sathyanarayanan.kuppuswamy@linux.intel.com wrote: >> From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com> >> >> When IOMMU tries to enable Page Request Interface (PRI) for VF device >> in iommu_enable_dev_iotlb(), it always fails because PRI support for >> PCIe VF device is currently broken. Current implementation expects >> the given PCIe device (PF & VF) to implement PRI capability before >> enabling the PRI support. But this assumption is incorrect. As per PCIe >> spec r4.0, sec 9.3.7.11, all VFs associated with PF can only use the >> PRI of the PF and not implement it. Hence we need to create exception >> for handling the PRI support for PCIe VF device. >> >> Also, since PRI is a shared resource between PF/VF, following rules >> should apply. >> >> 1. Use proper locking before accessing/modifying PF resources in VF >> PRI enable/disable call. >> 2. Use reference count logic to track the usage of PRI resource. >> 3. Disable PRI only if the PRI reference count (pri_ref_cnt) is zero. >> >> Cc: Ashok Raj <ashok.raj@intel.com> >> Cc: Keith Busch <keith.busch@intel.com> >> Suggested-by: Ashok Raj <ashok.raj@intel.com> >> Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com> >> --- >> drivers/pci/ats.c | 143 ++++++++++++++++++++++++++++++++++---------- >> include/linux/pci.h | 2 + >> 2 files changed, 112 insertions(+), 33 deletions(-) >> >> diff --git a/drivers/pci/ats.c b/drivers/pci/ats.c >> index 1f4be27a071d..079dc5444444 100644 >> --- a/drivers/pci/ats.c >> +++ b/drivers/pci/ats.c >> @@ -189,6 +189,8 @@ void pci_pri_init(struct pci_dev *pdev) >> if (pdev->is_virtfn) >> return; >> >> + mutex_init(&pdev->pri_lock); >> + >> pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PRI); >> if (!pos) >> return; >> @@ -221,29 +223,57 @@ int pci_enable_pri(struct pci_dev *pdev, u32 reqs) >> { >> u16 control, status; >> u32 max_requests; >> + int ret = 0; >> + struct pci_dev *pf = pci_physfn(pdev); >> >> - if (WARN_ON(pdev->pri_enabled)) >> - return -EBUSY; >> + mutex_lock(&pf->pri_lock); >> >> - if (!pdev->pri_cap) >> - return -EINVAL; >> + if (WARN_ON(pdev->pri_enabled)) { >> + ret = -EBUSY; >> + goto pri_unlock; >> + } >> >> - pci_read_config_word(pdev, pdev->pri_cap + PCI_PRI_STATUS, &status); >> - if (!(status & PCI_PRI_STATUS_STOPPED)) >> - return -EBUSY; >> + if (!pf->pri_cap) { >> + ret = -EINVAL; >> + goto pri_unlock; >> + } >> + >> + if (pdev->is_virtfn && pf->pri_enabled) >> + goto update_status; >> + >> + /* >> + * Before updating PRI registers, make sure there is no >> + * outstanding PRI requests. >> + */ >> + pci_read_config_word(pf, pf->pri_cap + PCI_PRI_STATUS, &status); >> + if (!(status & PCI_PRI_STATUS_STOPPED)) { >> + ret = -EBUSY; >> + goto pri_unlock; >> + } >> >> - pci_read_config_dword(pdev, pdev->pri_cap + PCI_PRI_MAX_REQ, >> - &max_requests); >> + pci_read_config_dword(pf, pf->pri_cap + PCI_PRI_MAX_REQ, &max_requests); >> reqs = min(max_requests, reqs); >> - pdev->pri_reqs_alloc = reqs; >> - pci_write_config_dword(pdev, pdev->pri_cap + PCI_PRI_ALLOC_REQ, reqs); >> + pf->pri_reqs_alloc = reqs; >> + pci_write_config_dword(pf, pf->pri_cap + PCI_PRI_ALLOC_REQ, reqs); >> >> control = PCI_PRI_CTRL_ENABLE; >> - pci_write_config_word(pdev, pdev->pri_cap + PCI_PRI_CTRL, control); >> + pci_write_config_word(pf, pf->pri_cap + PCI_PRI_CTRL, control); >> >> - pdev->pri_enabled = 1; >> + /* >> + * If PRI is not already enabled in PF, increment the PF >> + * pri_ref_cnt to track the usage of PRI interface. >> + */ >> + if (pdev->is_virtfn && !pf->pri_enabled) { >> + atomic_inc(&pf->pri_ref_cnt); >> + pf->pri_enabled = 1; >> + } >> >> - return 0; >> +update_status: >> + atomic_inc(&pf->pri_ref_cnt); >> + pdev->pri_enabled = 1; >> +pri_unlock: >> + mutex_unlock(&pf->pri_lock); >> + return ret; >> } >> EXPORT_SYMBOL_GPL(pci_enable_pri); >> >> @@ -256,18 +286,30 @@ EXPORT_SYMBOL_GPL(pci_enable_pri); >> void pci_disable_pri(struct pci_dev *pdev) >> { >> u16 control; >> + struct pci_dev *pf = pci_physfn(pdev); >> >> - if (WARN_ON(!pdev->pri_enabled)) >> - return; >> + mutex_lock(&pf->pri_lock); >> >> - if (!pdev->pri_cap) >> - return; >> + if (WARN_ON(!pdev->pri_enabled) || !pf->pri_cap) >> + goto pri_unlock; >> + >> + atomic_dec(&pf->pri_ref_cnt); >> >> - pci_read_config_word(pdev, pdev->pri_cap + PCI_PRI_CTRL, &control); >> + /* >> + * If pri_ref_cnt is not zero, then don't modify hardware >> + * registers. >> + */ >> + if (atomic_read(&pf->pri_ref_cnt)) >> + goto done; >> + >> + pci_read_config_word(pf, pf->pri_cap + PCI_PRI_CTRL, &control); >> control &= ~PCI_PRI_CTRL_ENABLE; >> - pci_write_config_word(pdev, pdev->pri_cap + PCI_PRI_CTRL, control); >> + pci_write_config_word(pf, pf->pri_cap + PCI_PRI_CTRL, control); >> >> +done: >> pdev->pri_enabled = 0; >> +pri_unlock: >> + mutex_unlock(&pf->pri_lock); >> } >> EXPORT_SYMBOL_GPL(pci_disable_pri); >> >> @@ -277,17 +319,31 @@ EXPORT_SYMBOL_GPL(pci_disable_pri); >> */ >> void pci_restore_pri_state(struct pci_dev *pdev) >> { >> - u16 control = PCI_PRI_CTRL_ENABLE; >> - u32 reqs = pdev->pri_reqs_alloc; >> + u16 control; >> + u32 reqs; >> + struct pci_dev *pf = pci_physfn(pdev); >> >> if (!pdev->pri_enabled) >> return; >> >> - if (!pdev->pri_cap) >> + if (!pf->pri_cap) >> return; >> >> - 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); >> + mutex_lock(&pf->pri_lock); >> + >> + /* If PRI is already enabled by other VF's or PF, return */ >> + pci_read_config_word(pf, pf->pri_cap + PCI_PRI_CTRL, &control); >> + if (control & PCI_PRI_CTRL_ENABLE) >> + goto pri_unlock; >> + >> + reqs = pf->pri_reqs_alloc; >> + control = PCI_PRI_CTRL_ENABLE; >> + >> + pci_write_config_dword(pf, pf->pri_cap + PCI_PRI_ALLOC_REQ, reqs); >> + pci_write_config_word(pf, pf->pri_cap + PCI_PRI_CTRL, control); > Why use "control" here instead of just PCI_PRI_CTRL_ENABLE? It can be done. Even in original code, using control did not serve any purpose. I just left the implementation as original code. > >> +pri_unlock: >> + mutex_unlock(&pf->pri_lock); >> } >> EXPORT_SYMBOL_GPL(pci_restore_pri_state); >> >> @@ -300,18 +356,32 @@ EXPORT_SYMBOL_GPL(pci_restore_pri_state); >> */ >> int pci_reset_pri(struct pci_dev *pdev) >> { >> + struct pci_dev *pf = pci_physfn(pdev); >> u16 control; >> + int ret = 0; >> >> - if (WARN_ON(pdev->pri_enabled)) >> - return -EBUSY; >> + mutex_lock(&pf->pri_lock); >> >> - if (!pdev->pri_cap) >> - return -EINVAL; >> + if (WARN_ON(pdev->pri_enabled)) { >> + ret = -EBUSY; >> + goto done; >> + } >> + >> + if (!pf->pri_cap) { >> + ret = -EINVAL; >> + goto done; >> + } >> + >> + /* If PRI is already enabled by other VF's or PF, return 0 */ >> + if (pf->pri_enabled) >> + goto done; >> >> control = PCI_PRI_CTRL_RESET; >> - pci_write_config_word(pdev, pdev->pri_cap + PCI_PRI_CTRL, control); >> >> - return 0; >> + pci_write_config_word(pf, pf->pri_cap + PCI_PRI_CTRL, control); > Also here (you didn't add this one, but "control" is completely > pointless in this function). > >> +done: >> + mutex_unlock(&pf->pri_lock); >> + return ret; >> } >> EXPORT_SYMBOL_GPL(pci_reset_pri); >> #endif /* CONFIG_PCI_PRI */ >> @@ -475,11 +545,18 @@ EXPORT_SYMBOL_GPL(pci_pasid_features); >> int pci_prg_resp_pasid_required(struct pci_dev *pdev) >> { >> u16 status; >> + struct pci_dev *pf = pci_physfn(pdev); >> + >> + mutex_lock(&pf->pri_lock); >> >> - if (!pdev->pri_cap) >> + if (!pf->pri_cap) { >> + mutex_unlock(&pf->pri_lock); >> return 0; >> + } >> + >> + pci_read_config_word(pf, pf->pri_cap + PCI_PRI_STATUS, &status); >> >> - pci_read_config_word(pdev, pdev->pri_cap + PCI_PRI_STATUS, &status); >> + mutex_unlock(&pf->pri_lock); >> >> if (status & PCI_PRI_STATUS_PASID) >> return 1; >> diff --git a/include/linux/pci.h b/include/linux/pci.h >> index 27224c0db849..3c9c4c82be27 100644 >> --- a/include/linux/pci.h >> +++ b/include/linux/pci.h >> @@ -455,8 +455,10 @@ struct pci_dev { >> atomic_t ats_ref_cnt; /* Number of VFs with ATS enabled */ >> #endif >> #ifdef CONFIG_PCI_PRI >> + struct mutex pri_lock; /* PRI enable lock */ >> u16 pri_cap; /* PRI Capability offset */ >> u32 pri_reqs_alloc; /* Number of PRI requests allocated */ >> + atomic_t pri_ref_cnt; /* Number of PF/VF PRI users */ >> #endif >> #ifdef CONFIG_PCI_PASID >> u16 pasid_cap; /* PASID Capability offset */ >> -- >> 2.21.0 >> -- Sathyanarayanan Kuppuswamy Linux kernel developer
next prev parent reply index Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-08-02 0:05 [PATCH v5 0/7] Fix PF/VF dependency issue sathyanarayanan.kuppuswamy 2019-08-02 0:05 ` [PATCH v5 1/7] PCI/ATS: Fix pci_prg_resp_pasid_required() dependency issues sathyanarayanan.kuppuswamy 2019-08-12 20:04 ` Bjorn Helgaas 2019-08-12 20:20 ` sathyanarayanan kuppuswamy 2019-08-13 3:51 ` Bjorn Helgaas 2019-08-16 18:06 ` Kuppuswamy Sathyanarayanan 2019-08-02 0:05 ` [PATCH v5 2/7] PCI/ATS: Initialize PRI in pci_ats_init() sathyanarayanan.kuppuswamy 2019-08-12 20:04 ` Bjorn Helgaas 2019-08-12 21:35 ` sathyanarayanan kuppuswamy 2019-08-13 4:10 ` Bjorn Helgaas 2019-08-15 4:46 ` Bjorn Helgaas 2019-08-15 17:30 ` Kuppuswamy Sathyanarayanan 2019-08-16 17:31 ` Bjorn Helgaas 2019-08-02 0:06 ` [PATCH v5 3/7] PCI/ATS: Initialize PASID " sathyanarayanan.kuppuswamy 2019-08-12 20:04 ` Bjorn Helgaas 2019-08-15 4:48 ` Bjorn Helgaas 2019-08-15 4:56 ` Bjorn Helgaas 2019-08-15 17:31 ` Kuppuswamy Sathyanarayanan 2019-08-02 0:06 ` [PATCH v5 4/7] PCI/ATS: Add PRI support for PCIe VF devices sathyanarayanan.kuppuswamy 2019-08-12 20:04 ` Bjorn Helgaas 2019-08-12 21:40 ` sathyanarayanan kuppuswamy [this message] 2019-08-13 4:16 ` Bjorn Helgaas 2019-08-15 22:20 ` Bjorn Helgaas 2019-08-15 22:39 ` Kuppuswamy Sathyanarayanan 2019-08-19 14:15 ` Bjorn Helgaas 2019-08-19 22:53 ` Kuppuswamy Sathyanarayanan 2019-08-19 23:19 ` Bjorn Helgaas 2019-08-28 18:21 ` Kuppuswamy Sathyanarayanan 2019-08-28 18:57 ` Bjorn Helgaas 2019-08-02 0:06 ` [PATCH v5 5/7] PCI/ATS: Add PASID " sathyanarayanan.kuppuswamy 2019-08-12 20:05 ` Bjorn Helgaas 2019-08-13 22:19 ` Kuppuswamy Sathyanarayanan 2019-08-15 5:04 ` Bjorn Helgaas 2019-08-16 1:21 ` Kuppuswamy Sathyanarayanan 2019-08-02 0:06 ` [PATCH v5 6/7] PCI/ATS: Disable PF/VF ATS service independently sathyanarayanan.kuppuswamy 2019-08-02 0:06 ` [PATCH v5 7/7] PCI: Skip Enhanced Allocation (EA) initialization for VF device sathyanarayanan.kuppuswamy
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