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Bjorn Helgaas
edc90fee91
Previously, we allocated pci_ats structures when an IOMMU driver called
pci_enable_ats(). An SR-IOV VF shares the STU setting with its PF, so when
enabling ATS on the VF, we allocated a pci_ats struct for the PF if it
didn't already have one. We held the sriov->lock to serialize threads
concurrently enabling ATS on several VFS so only one would allocate the PF
pci_ats.
Gregor reported a deadlock here:
pci_enable_sriov
sriov_enable
virtfn_add
mutex_lock(dev->sriov->lock) # acquire sriov->lock
pci_device_add
device_add
BUS_NOTIFY_ADD_DEVICE notifier chain
iommu_bus_notifier
amd_iommu_add_device # iommu_ops.add_device
init_iommu_group
iommu_group_get_for_dev
iommu_group_add_device
__iommu_attach_device
amd_iommu_attach_device # iommu_ops.attach_device
attach_device
pci_enable_ats
mutex_lock(dev->sriov->lock) # deadlock
There's no reason to delay allocating the pci_ats struct, and if we
allocate it for each device at enumeration-time, there's no need for
locking in pci_enable_ats().
Allocate pci_ats struct during enumeration, when we initialize other
capabilities.
Note that this implementation requires ATS to be enabled on the PF first,
before on any of the VFs because the PF controls the STU for all the VFs.
Link: http://permalink.gmane.org/gmane.linux.kernel.iommu/9433
Reported-by: Gregor Dick <gdick@solarflare.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Joerg Roedel <jroedel@suse.de>
111 lines
2.1 KiB
C
111 lines
2.1 KiB
C
#ifndef LINUX_PCI_ATS_H
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#define LINUX_PCI_ATS_H
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#include <linux/pci.h>
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/* Address Translation Service */
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struct pci_ats {
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int pos; /* capability position */
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int stu; /* Smallest Translation Unit */
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int qdep; /* Invalidate Queue Depth */
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atomic_t ref_cnt; /* number of VFs with ATS enabled */
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unsigned int is_enabled:1; /* Enable bit is set */
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};
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#ifdef CONFIG_PCI_ATS
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int pci_enable_ats(struct pci_dev *dev, int ps);
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void pci_disable_ats(struct pci_dev *dev);
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int pci_ats_queue_depth(struct pci_dev *dev);
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/**
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* pci_ats_enabled - query the ATS status
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* @dev: the PCI device
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*
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* Returns 1 if ATS capability is enabled, or 0 if not.
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*/
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static inline int pci_ats_enabled(struct pci_dev *dev)
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{
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return dev->ats && dev->ats->is_enabled;
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}
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#else /* CONFIG_PCI_ATS */
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static inline int pci_enable_ats(struct pci_dev *dev, int ps)
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{
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return -ENODEV;
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}
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static inline void pci_disable_ats(struct pci_dev *dev)
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{
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}
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static inline int pci_ats_queue_depth(struct pci_dev *dev)
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{
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return -ENODEV;
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}
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static inline int pci_ats_enabled(struct pci_dev *dev)
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{
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return 0;
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}
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#endif /* CONFIG_PCI_ATS */
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#ifdef CONFIG_PCI_PRI
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int pci_enable_pri(struct pci_dev *pdev, u32 reqs);
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void pci_disable_pri(struct pci_dev *pdev);
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int pci_reset_pri(struct pci_dev *pdev);
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#else /* CONFIG_PCI_PRI */
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static inline int pci_enable_pri(struct pci_dev *pdev, u32 reqs)
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{
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return -ENODEV;
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}
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static inline void pci_disable_pri(struct pci_dev *pdev)
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{
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}
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static inline int pci_reset_pri(struct pci_dev *pdev)
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{
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return -ENODEV;
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}
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#endif /* CONFIG_PCI_PRI */
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#ifdef CONFIG_PCI_PASID
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int pci_enable_pasid(struct pci_dev *pdev, int features);
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void pci_disable_pasid(struct pci_dev *pdev);
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int pci_pasid_features(struct pci_dev *pdev);
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int pci_max_pasids(struct pci_dev *pdev);
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#else /* CONFIG_PCI_PASID */
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static inline int pci_enable_pasid(struct pci_dev *pdev, int features)
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{
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return -EINVAL;
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}
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static inline void pci_disable_pasid(struct pci_dev *pdev)
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{
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}
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static inline int pci_pasid_features(struct pci_dev *pdev)
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{
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return -EINVAL;
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}
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static inline int pci_max_pasids(struct pci_dev *pdev)
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{
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return -EINVAL;
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}
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#endif /* CONFIG_PCI_PASID */
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#endif /* LINUX_PCI_ATS_H*/
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