On s390 systems, which use a machine level hypervisor, PCI devices are always accessed through a form of PCI pass-through which fundamentally operates on a per PCI function granularity. This is also reflected in the s390 PCI hotplug driver which creates hotplug slots for individual PCI functions. Its reset_slot() function, which is a wrapper for zpci_hot_reset_device(), thus also resets individual functions. Currently, the kernel's PCI_SLOT() macro assigns the same pci_slot object to multifunction devices. This approach worked fine on s390 systems that only exposed virtual functions as individual PCI domains to the operating system. Since commit 44510d6fa0c0 ("s390/pci: Handling multifunctions") s390 supports exposing the topology of multifunction PCI devices by grouping them in a shared PCI domain. When attempting to reset a function through the hotplug driver, the shared slot assignment causes the wrong function to be reset instead of the intended one. It also leaks memory as we do create a pci_slot object for the function, but don't correctly free it in pci_slot_release(). This patch adds a helper function to allow per function PCI slots for functions managed through a hypervisor which exposes individual PCI functions while retaining the topology. Fixes: 44510d6fa0c0 ("s390/pci: Handling multifunctions") Co-developed-by: Niklas Schnelle Signed-off-by: Niklas Schnelle Signed-off-by: Farhan Ali --- drivers/pci/slot.c | 19 ++++++++++++++++--- 1 file changed, 16 insertions(+), 3 deletions(-) diff --git a/drivers/pci/slot.c b/drivers/pci/slot.c index 50fb3eb595fe..991526af0ffe 100644 --- a/drivers/pci/slot.c +++ b/drivers/pci/slot.c @@ -5,6 +5,7 @@ * Alex Chiang */ +#include #include #include #include @@ -73,7 +74,7 @@ static void pci_slot_release(struct kobject *kobj) down_read(&pci_bus_sem); list_for_each_entry(dev, &slot->bus->devices, bus_list) - if (PCI_SLOT(dev->devfn) == slot->number) + if (dev->slot == slot->number) dev->slot = NULL; up_read(&pci_bus_sem); @@ -160,13 +161,25 @@ static int rename_slot(struct pci_slot *slot, const char *name) return result; } +static bool pci_dev_matches_slot(struct pci_dev *dev, struct pci_slot *slot) +{ + if (hypervisor_isolated_pci_functions()) { + if (dev->devfn == slot->number) + return true; + } else { + if (PCI_SLOT(dev->devfn) == slot->number) + return true; + } + return false; +} + void pci_dev_assign_slot(struct pci_dev *dev) { struct pci_slot *slot; mutex_lock(&pci_slot_mutex); list_for_each_entry(slot, &dev->bus->slots, list) - if (PCI_SLOT(dev->devfn) == slot->number) + if (pci_dev_matches_slot(dev, slot)) dev->slot = slot; mutex_unlock(&pci_slot_mutex); } @@ -285,7 +298,7 @@ struct pci_slot *pci_create_slot(struct pci_bus *parent, int slot_nr, down_read(&pci_bus_sem); list_for_each_entry(dev, &parent->devices, bus_list) - if (PCI_SLOT(dev->devfn) == slot_nr) + if (pci_dev_matches_slot(dev, slot)) dev->slot = slot; up_read(&pci_bus_sem); -- 2.43.0