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().
Add a flag for struct pci_slot 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") Cc: stable@vger.kernel.org Suggested-by: Niklas Schnelle schnelle@linux.ibm.com Reviewed-by: Benjamin Block bblock@linux.ibm.com Signed-off-by: Farhan Ali alifm@linux.ibm.com --- drivers/pci/hotplug/s390_pci_hpc.c | 10 ++++++++-- drivers/pci/pci.c | 5 +++-- drivers/pci/slot.c | 14 +++++++++++--- include/linux/pci.h | 1 + 4 files changed, 23 insertions(+), 7 deletions(-)
diff --git a/drivers/pci/hotplug/s390_pci_hpc.c b/drivers/pci/hotplug/s390_pci_hpc.c index d9996516f49e..8b547de464bf 100644 --- a/drivers/pci/hotplug/s390_pci_hpc.c +++ b/drivers/pci/hotplug/s390_pci_hpc.c @@ -126,14 +126,20 @@ static const struct hotplug_slot_ops s390_hotplug_slot_ops = {
int zpci_init_slot(struct zpci_dev *zdev) { + int ret; char name[SLOT_NAME_SIZE]; struct zpci_bus *zbus = zdev->zbus;
zdev->hotplug_slot.ops = &s390_hotplug_slot_ops;
snprintf(name, SLOT_NAME_SIZE, "%08x", zdev->fid); - return pci_hp_register(&zdev->hotplug_slot, zbus->bus, - zdev->devfn, name); + ret = pci_hp_register(&zdev->hotplug_slot, zbus->bus, + zdev->devfn, name); + if (ret) + return ret; + + zdev->hotplug_slot.pci_slot->per_func_slot = 1; + return 0; }
void zpci_exit_slot(struct zpci_dev *zdev) diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index b14dd064006c..36ee38e0d817 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -4980,8 +4980,9 @@ static int pci_reset_hotplug_slot(struct hotplug_slot *hotplug, bool probe)
static int pci_dev_reset_slot_function(struct pci_dev *dev, bool probe) { - if (dev->multifunction || dev->subordinate || !dev->slot || - dev->dev_flags & PCI_DEV_FLAGS_NO_BUS_RESET) + if (dev->subordinate || !dev->slot || + dev->dev_flags & PCI_DEV_FLAGS_NO_BUS_RESET || + (dev->multifunction && !dev->slot->per_func_slot)) return -ENOTTY;
return pci_reset_hotplug_slot(dev->slot->hotplug, probe); diff --git a/drivers/pci/slot.c b/drivers/pci/slot.c index 50fb3eb595fe..51ee59e14393 100644 --- a/drivers/pci/slot.c +++ b/drivers/pci/slot.c @@ -63,6 +63,14 @@ static ssize_t cur_speed_read_file(struct pci_slot *slot, char *buf) return bus_speed_read(slot->bus->cur_bus_speed, buf); }
+static bool pci_dev_matches_slot(struct pci_dev *dev, struct pci_slot *slot) +{ + if (slot->per_func_slot) + return dev->devfn == slot->number; + + return PCI_SLOT(dev->devfn) == slot->number; +} + static void pci_slot_release(struct kobject *kobj) { struct pci_dev *dev; @@ -73,7 +81,7 @@ 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 (pci_dev_matches_slot(dev, slot)) dev->slot = NULL; up_read(&pci_bus_sem);
@@ -166,7 +174,7 @@ void pci_dev_assign_slot(struct pci_dev *dev)
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 +293,7 @@ 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);
diff --git a/include/linux/pci.h b/include/linux/pci.h index d1fdf81fbe1e..6ad194597ab5 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -78,6 +78,7 @@ struct pci_slot { struct list_head list; /* Node in list of slots */ struct hotplug_slot *hotplug; /* Hotplug info (move here) */ unsigned char number; /* PCI_SLOT(pci_dev->devfn) */ + unsigned int per_func_slot:1; /* Allow per function slot */ struct kobject kobj; };