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On s390 PCI functions may be hotplugged individually even when they belong to a multi-function device. In particular on an SR-IOV device VFs may be removed and later re-added. In commita50297cf82("s390/pci: separate zbus creation from scanning") it was missed however that struct pci_bus and struct zpci_bus's resource list retained a reference to the PCI functions MMIO resources even though those resources are released and freed on hot-unplug. These stale resources may subsequently be claimed when the PCI function re-appears resulting in use-after-free. One idea of fixing this use-after-free in s390 specific code that was investigated was to simply keep resources around from the moment a PCI function first appeared until the whole virtual PCI bus created for a multi-function device disappears. The problem with this however is that due to the requirement of artificial MMIO addreesses (address cookies) extra logic is then needed to keep the address cookies compatible on re-plug. At the same time the MMIO resources semantically belong to the PCI function so tying their lifecycle to the function seems more logical. Instead a simpler approach is to remove the resources of an individually hot-unplugged PCI function from the PCI bus's resource list while keeping the resources of other PCI functions on the PCI bus untouched. This is done by introducing pci_bus_remove_resource() to remove an individual resource. Similarly the resource also needs to be removed from the struct zpci_bus's resource list. It turns out however, that there is really no need to add the MMIO resources to the struct zpci_bus's resource list at all and instead we can simply use the zpci_bar_struct's resource pointer directly. Fixes:a50297cf82("s390/pci: separate zbus creation from scanning") Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com> Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com> Acked-by: Bjorn Helgaas <bhelgaas@google.com> Link: https://lore.kernel.org/r/20230306151014.60913-2-schnelle@linux.ibm.com Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
43 lines
1.0 KiB
C
43 lines
1.0 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Copyright IBM Corp. 2020
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*
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* Author(s):
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* Pierre Morel <pmorel@linux.ibm.com>
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*
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*/
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int zpci_bus_device_register(struct zpci_dev *zdev, struct pci_ops *ops);
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void zpci_bus_device_unregister(struct zpci_dev *zdev);
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int zpci_bus_scan_bus(struct zpci_bus *zbus);
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void zpci_bus_scan_busses(void);
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int zpci_bus_scan_device(struct zpci_dev *zdev);
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void zpci_bus_remove_device(struct zpci_dev *zdev, bool set_error);
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void zpci_release_device(struct kref *kref);
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static inline void zpci_zdev_put(struct zpci_dev *zdev)
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{
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if (zdev)
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kref_put(&zdev->kref, zpci_release_device);
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}
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static inline void zpci_zdev_get(struct zpci_dev *zdev)
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{
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kref_get(&zdev->kref);
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}
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int zpci_alloc_domain(int domain);
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void zpci_free_domain(int domain);
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int zpci_setup_bus_resources(struct zpci_dev *zdev);
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static inline struct zpci_dev *zdev_from_bus(struct pci_bus *bus,
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unsigned int devfn)
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{
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struct zpci_bus *zbus = bus->sysdata;
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return (devfn >= ZPCI_FUNCTIONS_PER_BUS) ? NULL : zbus->function[devfn];
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}
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