kernel/arch/s390/include/asm/pci.h, branch linux-5.14.y

s390/pci: fix zpci_zdev_put() on reserve

2021-10-27T07:59:55Z

commit a46044a92add6a400f4dada7b943b30221f7cc80 upstream. Since commit 2a671f77ee49 ("s390/pci: fix use after free of zpci_dev") the reference count of a zpci_dev is incremented between pcibios_add_device() and pcibios_release_device() which was supposed to prevent the zpci_dev from being freed while the common PCI code has access to it. It was missed however that the handling of zPCI availability events assumed that once zpci_zdev_put() was called no later availability event would still see the device. With the previously mentioned commit however this assumption no longer holds and we must make sure that we only drop the initial long-lived reference the zPCI subsystem holds exactly once. Do so by introducing a zpci_device_reserved() function that handles when a device is reserved. Here we make sure the zpci_dev will not be considered for further events by removing it from the zpci_list. This also means that the device actually stays in the ZPCI_FN_STATE_RESERVED state between the time we know it has been reserved and the final reference going away. We thus need to consider it a real state instead of just a conceptual state after the removal. The final cleanup of PCI resources, removal from zbus, and destruction of the IOMMU stays in zpci_release_device() to make sure holders of the reference do see valid data until the release. Fixes: 2a671f77ee49 ("s390/pci: fix use after free of zpci_dev") Cc: stable@vger.kernel.org Signed-off-by: Niklas Schnelle Signed-off-by: Vasily Gorbik Signed-off-by: Greg Kroah-Hartman

s390/pci: add zpci_set_irq()/zpci_clear_irq()

2021-06-28T09:18:28Z

Pull the directed vs floating IRQ check into common zpci_set_irq()/zpci_clear_irq() functions and expose them for the rest of the zPCI subsystem. Furthermore we add a zdev flag bit to easily check if IRQs are registered. This is needed for use in resetting a zPCI function. Reviewed-by: Matthew Rosato Signed-off-by: Niklas Schnelle Signed-off-by: Vasily Gorbik

s390/pci: rename zpci_configure_device()

2021-04-30T15:17:00Z

With zpci_configure_device() now always called on a device that has already been configured on the platform level its name has become misleading. Rename it to zpci_scan_configured_device() to signify that the function now only handles the correct scanning of a newly configured PCI function taking care of the special handling necessary for function 0 and functions parked waiting for a PCI bus that can't be created without first seeing function 0. Reviewed-by: Matthew Rosato Reviewed-by: Pierre Morel Signed-off-by: Niklas Schnelle Signed-off-by: Heiko Carstens

s390/pci: separate zbus registration from scanning

2021-04-12T10:46:42Z

Now that the zbus can be created without being scanned we can go one step further and make registering a device to a zbus independent from scanning it. This way the zbus handling becomes much more natural in that functions can be registered on the zbus to be scanned later more closely resembling the handling of both real PCI hardware and other virtual PCI busses like Hyper-V's virtual PCI bus (see for example drivers/pci/controller/pci-hyperv.c:create_root_hv_pci_bus()). Having zbus registration separate from scanning allows us to return fully initialized but still disabled zdevs from zpci_create_device() which can then be configured just as we would configure a zdev from standby (minus the SCLP Configure already done by the platform). There is still the exception that a PCI function with non-zero devfn can be plugged before its PCI bus, which depends on the function with zero devfn, is created. In this case the zdev returend from zpci_create_device() is still missing its bus, hotplug slot, and resources which need to be created later but at least it doesn't wait in the enabled state and can otherwise be treated as initialized. With this we also separate the initial PCI scan using CLP List PCI Functions into two phases. In the CLP loop's callback we only register each function with a virtual zbus creating the latter as needed. Then, after we have built this virtual PCI topology based on our list of zbusses, we can make use of the common code functionality to scan each complete zbus as a separate child bus. Reviewed-by: Matthew Rosato Acked-by: Pierre Morel Signed-off-by: Niklas Schnelle Signed-off-by: Heiko Carstens

s390/pci: separate zbus creation from scanning

2021-04-12T10:46:42Z

In the existing code the creation of the PCI bus and the scanning of function zero all happens in zpci_scan_bus(). This in turn requires functions to be enabled and their resources to be available before the PCI bus is even created. This not only means that functions are enabled long before they are actually made available to the common PCI subsystem. In case of functions with non-zero devfn which appeared before the function with devfn zero they can wait arbitrarily long in this enabled but not scanned state. Fix this by separating the creation of the PCI bus from scanning it and only prepare, that is enable and setup MMIO bus resources, functions just before they are scanned. As they may be scanned multiple times track if we already created resources in the zdev. Reviewed-by: Matthew Rosato Acked-by: Pierre Morel Signed-off-by: Niklas Schnelle Signed-off-by: Heiko Carstens

s390/pci: move zpci_remove_device() to bus code

2021-03-22T10:36:04Z

The zpci_remove_device() function removes the device from the PCI common code core which is an operation dealing primarily with the zbus and PCI bus code. With that and to match an upcoming refactoring of the symmetric scanning part move it to the bus code. Reviewed-by: Matthew Rosato Signed-off-by: Niklas Schnelle Signed-off-by: Heiko Carstens

s390/pci: unify de-/configure for slots and events

2021-03-22T10:36:04Z

A zPCI event with PEC 0x0301 for an existing zPCI device goes through the same actions as enable_slot(). Similarly a zPCI event with PEC 0x0303 does the same steps as disable_slot(). We can thus unify both actions as zpci_configure_device() respectively zpci_deconfigure_device(). Reviewed-by: Matthew Rosato Signed-off-by: Niklas Schnelle Signed-off-by: Heiko Carstens

s390/pci: refactor zpci function states

2021-03-22T10:36:03Z

The current zdev->state mixes the configuration states supported by CLP with an additional Online state which is used inconsistently to include enabled zPCI functions which are not yet visible to the common PCI subsytem. In preparation for a clean separation between architected configuration states and fine grained function states remove the Online function state. Where we previously checked for Online it is more accurate to check if the function is enabled to avoid an edge case where a disabled device was still treated as Online. This also simplifies checks whether a function is configured as this is now directly reflected by its function state. Reviewed-by: Matthew Rosato Signed-off-by: Niklas Schnelle Signed-off-by: Heiko Carstens

s390/pci: fix leak of PCI device structure

2021-03-15T18:10:56Z

In commit 05bc1be6db4b2 ("s390/pci: create zPCI bus") we removed the pci_dev_put() call matching the earlier pci_get_slot() done as part of __zpci_event_availability(). This was based on the wrong understanding that the device_put() done as part of pci_destroy_device() would counter the pci_get_slot() when it only counters the initial reference. This same understanding and existing bad example also lead to not doing a pci_dev_put() in zpci_remove_device(). Since releasing the PCI devices, unlike releasing the PCI slot, does not print any debug message for testing I added one in pci_release_dev(). This revealed that we are indeed leaking the PCI device on PCI hotunplug. Further testing also revealed another missing pci_dev_put() in disable_slot(). Fix this by adding the missing pci_dev_put() in disable_slot() and fix zpci_remove_device() with the correct pci_dev_put() calls. Also instead of calling pci_get_slot() in __zpci_event_availability() to determine if a PCI device is registered and then doing the same again in zpci_remove_device() do this once in zpci_remove_device() which makes sure that the pdev in __zpci_event_availability() is only used for the result of pci_scan_single_device() which does not need a reference count decremnt as its ownership goes to the PCI bus. Also move the check if zdev->zbus->bus is set into zpci_remove_device() since it may be that we're removing a device with devfn != 0 which never had a PCI bus. So we can still set the pdev->error_state to indicate that the device is not usable anymore, add a flag to set the error state. Fixes: 05bc1be6db4b2 ("s390/pci: create zPCI bus") Cc: # 5.8+: e1bff843cde6 s390/pci: remove superfluous zdev->zbus check Cc: # 5.8+: ba764dd703fe s390/pci: refactor zpci_create_device() Cc: # 5.8+ Reviewed-by: Matthew Rosato Signed-off-by: Niklas Schnelle Signed-off-by: Heiko Carstens

s390/pci: refactor zpci_create_device()

2021-02-09T14:57:04Z

Currently zpci_create_device() is only called in clp_add_pci_device() which allocates the memory for the struct zpci_dev being created. There is little separation of concerns as only both functions together can create a zpci_dev and the only CLP specific code in clp_add_pci_device() is a call to clp_query_pci_fn(). Improve this by removing clp_add_pci_device() and refactor zpci_create_device() such that it alone creates and initializes the zpci_dev given the FID and Function Handle. For this we need to make clp_query_pci_fn() non-static. While at it remove the function handle parameter since we can just take that from the zpci_dev. Also move adding to the zpci_list to after the zdev has been fully created which eliminates a window where a partially initialized zdev can be found by get_zdev_by_fid(). Acked-by: Pierre Morel Signed-off-by: Niklas Schnelle Signed-off-by: Vasily Gorbik