kernel/drivers/pci/hotplug/s390_pci_hpc.c, branch linux-6.5.y

s390/pci: implement reset_slot for hotplug slot

2021-11-08T13:17:49Z

This is done by adding a zpci_hot_reset_device() call which does a low level reset of the PCI function without changing its higher level function state. This way it can be used while the zPCI function is bound to a driver and with DMA tables being controlled either through the IOMMU or DMA APIs which is prohibited when using zpci_disable_device() as that drop existing DMA translations. As this reset, unlike a normal FLR, also calls zpci_clear_irq() we need to implement arch_restore_msi_irqs() and make sure we re-enable IRQs for the PCI function if they were previously disabled. Reviewed-by: Pierre Morel Reviewed-by: Matthew Rosato Signed-off-by: Niklas Schnelle Signed-off-by: Vasily Gorbik

s390/pci: fix zpci_zdev_put() on reserve

2021-10-04T07:49:10Z

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

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: narrow scope of zpci_configure_device()

2021-04-12T10:46:42Z

Currently zpci_configure_device() can be called on a zPCI function in two completely different states. Either the underlying zPCI function has already been configured by the platform and we are only doing the scanning to get it usable by Linux drivers. Or the underlying function is in Standby and we first do an SCLP to get it configured. This makes zpci_configure_device() harder to reason about. Since calling zpci_configure_device() on a function in Standby only happens in enable_slot() simply pull out the SCLP call and setting of zdev->state and thus call zpci_configure_device() under the same circumstances as in the event handling code. Reviewed-by: Matthew Rosato Reviewed-by: Pierre Morel 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: re-introduce zpci_remove_device()

2020-08-17T11:17:25Z

For fixing the PF to VF link removal we need to perform some action on every removal of a zdev from the common PCI subsystem. So in preparation re-introduce zpci_remove_device() and use that instead of directly calling the common code functions. This was actually still declared from earlier code but no longer implemented. Reviewed-by: Pierre Morel Signed-off-by: Niklas Schnelle Signed-off-by: Heiko Carstens

s390/pci: Do not disable PF when VFs exist

2020-04-28T11:49:47Z

The Physical function should not be disabled until no virtual functions depends on it. Let's force the user to first use echo 0 > sriov_numfs before allowing to disable the PF with echo 0 > power. Signed-off-by: Pierre Morel Reviewed-by: Niklas Schnelle Signed-off-by: Vasily Gorbik

s390/pci: Handling multifunctions

2020-04-28T11:49:47Z

We allow multiple functions on a single bus. We suppress the ZPCI_DEVFN definition and replace its occurences with zpci->devfn. We verify the number of device during the registration. There can never be more domains in use than existing devices, so we do not need to verify the count of domain after having verified the count of devices. Signed-off-by: Pierre Morel Reviewed-by: Niklas Schnelle Signed-off-by: Vasily Gorbik