From: Bjorn Helgaas <helgaas@kernel.org> To: sathyanarayanan.kuppuswamy@linux.intel.com Cc: linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, ashok.raj@intel.com, keith.busch@intel.com Subject: Re: [PATCH v5 5/7] PCI/ATS: Add PASID support for PCIe VF devices Date: Mon, 12 Aug 2019 15:05:08 -0500 Message-ID: <20190812200508.GM11785@google.com> (raw) In-Reply-To: <d10b5f08212a42c4a710ec649bffe082599dbb46.1564702313.git.sathyanarayanan.kuppuswamy@linux.intel.com> On Thu, Aug 01, 2019 at 05:06:02PM -0700, sathyanarayanan.kuppuswamy@linux.intel.com wrote: > From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com> > > When IOMMU tries to enable PASID for VF device in > iommu_enable_dev_iotlb(), it always fails because PASID support for PCIe > VF device is currently broken in PCIE driver. Current implementation > expects the given PCIe device (PF & VF) to implement PASID capability > before enabling the PASID support. But this assumption is incorrect. As > per PCIe spec r4.0, sec 9.3.7.14, all VFs associated with PF can only > use the PASID of the PF and not implement it. > > Also, since PASID is a shared resource between PF/VF, following rules > should apply. > > 1. Use proper locking before accessing/modifying PF resources in VF > PASID enable/disable call. > 2. Use reference count logic to track the usage of PASID resource. > 3. Disable PASID only if the PASID reference count (pasid_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 | 113 ++++++++++++++++++++++++++++++++++---------- > include/linux/pci.h | 2 + > 2 files changed, 90 insertions(+), 25 deletions(-) > > diff --git a/drivers/pci/ats.c b/drivers/pci/ats.c > index 079dc5444444..9384afd7d00e 100644 > --- a/drivers/pci/ats.c > +++ b/drivers/pci/ats.c > @@ -402,6 +402,8 @@ void pci_pasid_init(struct pci_dev *pdev) > if (pdev->is_virtfn) > return; > > + mutex_init(&pdev->pasid_lock); > + > pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PASID); > if (!pos) > return; > @@ -436,32 +438,57 @@ void pci_pasid_init(struct pci_dev *pdev) > int pci_enable_pasid(struct pci_dev *pdev, int features) > { > u16 control, supported; > + int ret = 0; > + struct pci_dev *pf = pci_physfn(pdev); > > - if (WARN_ON(pdev->pasid_enabled)) > - return -EBUSY; > + mutex_lock(&pf->pasid_lock); > > - if (!pdev->eetlp_prefix_path) > - return -EINVAL; > + if (WARN_ON(pdev->pasid_enabled)) { > + ret = -EBUSY; > + goto pasid_unlock; > + } > > - if (!pdev->pasid_cap) > - return -EINVAL; > + if (!pdev->eetlp_prefix_path) { > + ret = -EINVAL; > + goto pasid_unlock; > + } > > - pci_read_config_word(pdev, pdev->pasid_cap + PCI_PASID_CAP, > - &supported); > + if (!pf->pasid_cap) { > + ret = -EINVAL; > + goto pasid_unlock; > + } > + > + if (pdev->is_virtfn && pf->pasid_enabled) > + goto update_status; > + > + pci_read_config_word(pf, pf->pasid_cap + PCI_PASID_CAP, &supported); > supported &= PCI_PASID_CAP_EXEC | PCI_PASID_CAP_PRIV; > > /* User wants to enable anything unsupported? */ > - if ((supported & features) != features) > - return -EINVAL; > + if ((supported & features) != features) { > + ret = -EINVAL; > + goto pasid_unlock; > + } > > control = PCI_PASID_CTRL_ENABLE | features; > - pdev->pasid_features = features; > - > + pf->pasid_features = features; > pci_write_config_word(pdev, pdev->pasid_cap + PCI_PASID_CTRL, control); > > - pdev->pasid_enabled = 1; > + /* > + * If PASID is not already enabled in PF, increment pasid_ref_cnt > + * to count PF PASID usage. > + */ > + if (pdev->is_virtfn && !pf->pasid_enabled) { > + atomic_inc(&pf->pasid_ref_cnt); > + pf->pasid_enabled = 1; > + } > > - return 0; > +update_status: > + atomic_inc(&pf->pasid_ref_cnt); > + pdev->pasid_enabled = 1; > +pasid_unlock: > + mutex_unlock(&pf->pasid_lock); > + return ret; > } > EXPORT_SYMBOL_GPL(pci_enable_pasid); > > @@ -472,16 +499,29 @@ EXPORT_SYMBOL_GPL(pci_enable_pasid); > void pci_disable_pasid(struct pci_dev *pdev) > { > u16 control = 0; > + struct pci_dev *pf = pci_physfn(pdev); > + > + mutex_lock(&pf->pasid_lock); > > if (WARN_ON(!pdev->pasid_enabled)) > - return; > + goto pasid_unlock; > > - if (!pdev->pasid_cap) > - return; > + if (!pf->pasid_cap) > + goto pasid_unlock; > > - pci_write_config_word(pdev, pdev->pasid_cap + PCI_PASID_CTRL, control); > + atomic_dec(&pf->pasid_ref_cnt); > > + if (atomic_read(&pf->pasid_ref_cnt)) > + goto done; > + > + /* Disable PASID only if pasid_ref_cnt is zero */ > + pci_write_config_word(pf, pf->pasid_cap + PCI_PASID_CTRL, control); > + > +done: > pdev->pasid_enabled = 0; > +pasid_unlock: > + mutex_unlock(&pf->pasid_lock); > + > } > EXPORT_SYMBOL_GPL(pci_disable_pasid); > > @@ -492,15 +532,25 @@ EXPORT_SYMBOL_GPL(pci_disable_pasid); > void pci_restore_pasid_state(struct pci_dev *pdev) > { > u16 control; > + struct pci_dev *pf = pci_physfn(pdev); > > if (!pdev->pasid_enabled) > return; > > - if (!pdev->pasid_cap) > + if (!pf->pasid_cap) > return; > > + mutex_lock(&pf->pasid_lock); > + > + pci_read_config_word(pf, pf->pasid_cap + PCI_PASID_CTRL, &control); > + if (control & PCI_PASID_CTRL_ENABLE) > + goto pasid_unlock; > + > control = PCI_PASID_CTRL_ENABLE | pdev->pasid_features; > - pci_write_config_word(pdev, pdev->pasid_cap + PCI_PASID_CTRL, control); > + pci_write_config_word(pf, pf->pasid_cap + PCI_PASID_CTRL, control); > + > +pasid_unlock: > + mutex_unlock(&pf->pasid_lock); > } > EXPORT_SYMBOL_GPL(pci_restore_pasid_state); > > @@ -517,15 +567,22 @@ EXPORT_SYMBOL_GPL(pci_restore_pasid_state); > int pci_pasid_features(struct pci_dev *pdev) > { > u16 supported; > + struct pci_dev *pf = pci_physfn(pdev); > + > + mutex_lock(&pf->pasid_lock); > > - if (!pdev->pasid_cap) > + if (!pf->pasid_cap) { > + mutex_unlock(&pf->pasid_lock); > return -EINVAL; > + } > > - pci_read_config_word(pdev, pdev->pasid_cap + PCI_PASID_CAP, > + pci_read_config_word(pf, pf->pasid_cap + PCI_PASID_CAP, > &supported); > > supported &= PCI_PASID_CAP_EXEC | PCI_PASID_CAP_PRIV; > > + mutex_unlock(&pf->pasid_lock); > + > return supported; > } > EXPORT_SYMBOL_GPL(pci_pasid_features); > @@ -579,15 +636,21 @@ EXPORT_SYMBOL_GPL(pci_prg_resp_pasid_required); > int pci_max_pasids(struct pci_dev *pdev) > { > u16 supported; > + struct pci_dev *pf = pci_physfn(pdev); > + > + mutex_lock(&pf->pasid_lock); > > - if (!pdev->pasid_cap) > + if (!pf->pasid_cap) { > + mutex_unlock(&pf->pasid_lock); > return -EINVAL; > + } > > - pci_read_config_word(pdev, pdev->pasid_cap + PCI_PASID_CAP, > - &supported); > + pci_read_config_word(pf, pf->pasid_cap + PCI_PASID_CAP, &supported); > > supported = (supported & PASID_NUMBER_MASK) >> PASID_NUMBER_SHIFT; > > + mutex_unlock(&pf->pasid_lock); > + > return (1 << supported); > } > EXPORT_SYMBOL_GPL(pci_max_pasids); > diff --git a/include/linux/pci.h b/include/linux/pci.h > index 3c9c4c82be27..4bfcca045afd 100644 > --- a/include/linux/pci.h > +++ b/include/linux/pci.h > @@ -461,8 +461,10 @@ struct pci_dev { > atomic_t pri_ref_cnt; /* Number of PF/VF PRI users */ > #endif > #ifdef CONFIG_PCI_PASID > + struct mutex pasid_lock; /* PASID enable lock */ I think these locks are finer-grained than necessary. I'm not sure it's worth having two mutexes for every device (one for PRI and another for PASID). Is there really a performance benefit for having two? Do it (or do they) need to be in struct pci_dev? You only use the PF mutexes, so maybe it could be in the struct pci_sriov, which I think is only one per PF. > u16 pasid_cap; /* PASID Capability offset */ > u16 pasid_features; > + atomic_t pasid_ref_cnt; /* Number of VFs with PASID enabled */ > #endif > #ifdef CONFIG_PCI_P2PDMA > struct pci_p2pdma *p2pdma; > -- > 2.21.0 >
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 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 [this message] 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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