Revert "PCI: Avoid reset when disabled via sysfs"

commit bc0b828ef6e561081ebc4c758d0c4d166bb9829c upstream.

This reverts commit 479380efe1625e251008d24b2810283db60d6fcd.

The reset_method attribute on a PCI device is only intended to manage the
availability of function scoped resets for a device.  It was never intended
to restrict resets targeting the bus or slot.

In introducing a restriction that each device must support function level
reset by testing pci_reset_supported(), we essentially create a catch-22,
that a device must have a function scope reset in order to support bus/slot
reset, when we use bus/slot reset to effect a reset of a device that does
not support a function scoped reset, especially multi-function devices.

This breaks the majority of uses cases where vfio-pci uses bus/slot resets
to manage multifunction devices that do not support function scoped resets.

Fixes: 479380efe162 ("PCI: Avoid reset when disabled via sysfs")
Reported-by: Cal Peake <cp@absolutedigital.net>
Closes: https://lore.kernel.org/all/808e1111-27b7-f35b-6d5c-5b275e73677b@absolutedigital.net
Reported-by: Athul Krishna <athul.krishna.kr@protonmail.com>
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=220010
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20250414211828.3530741-1-alex.williamson@redhat.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index bcce569a8339562c9f1c595e46c98007a23a35e0..095fa1910d36db2a82c6d3d1a316076a95b18877 100644 (file)
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -5714,8 +5714,6 @@ static bool pci_bus_resettable(struct pci_bus *bus)
                return false;
 
        list_for_each_entry(dev, &bus->devices, bus_list) {
-               if (!pci_reset_supported(dev))
-                       return false;
                if (dev->dev_flags & PCI_DEV_FLAGS_NO_BUS_RESET ||
                    (dev->subordinate && !pci_bus_resettable(dev->subordinate)))
                        return false;
@@ -5792,8 +5790,6 @@ static bool pci_slot_resettable(struct pci_slot *slot)
        list_for_each_entry(dev, &slot->bus->devices, bus_list) {
                if (!dev->slot || dev->slot != slot)
                        continue;
-               if (!pci_reset_supported(dev))
-                       return false;
                if (dev->dev_flags & PCI_DEV_FLAGS_NO_BUS_RESET ||
                    (dev->subordinate && !pci_bus_resettable(dev->subordinate)))
                        return false;