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 Link: https://lore.kernel.org/all/808e1111-27b7-f35b-6d5c-5b275e73677b@absolutedig... Cc: stable@vger.kernel.org Signed-off-by: Alex Williamson alex.williamson@redhat.com --- drivers/pci/pci.c | 4 ---- 1 file changed, 4 deletions(-)
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index 4d7c9f64ea24..e77d5b53c0ce 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -5429,8 +5429,6 @@ 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; @@ -5507,8 +5505,6 @@ 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;
From: Alex Williamson alex.williamson@redhat.com Sent: Tuesday, April 15, 2025 5:18 AM
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 Link: https://lore.kernel.org/all/808e1111-27b7-f35b-6d5c- 5b275e73677b@absolutedigital.net Cc: stable@vger.kernel.org Signed-off-by: Alex Williamson alex.williamson@redhat.com
Reviewed-by: Kevin Tian kevin.tian@intel.com
On Mon, Apr 14, 2025 at 03:18:23PM -0600, Alex Williamson wrote:
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 Link: https://lore.kernel.org/all/808e1111-27b7-f35b-6d5c-5b275e73677b@absolutedig... Cc: stable@vger.kernel.org Signed-off-by: Alex Williamson alex.williamson@redhat.com
Applied with Kevin's reviewed-by to pci/for-linus for v6.15, thanks, and sorry for the breakage.
drivers/pci/pci.c | 4 ---- 1 file changed, 4 deletions(-)
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index 4d7c9f64ea24..e77d5b53c0ce 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -5429,8 +5429,6 @@ 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;@@ -5507,8 +5505,6 @@ 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;-- 2.48.1
linux-stable-mirror@lists.linaro.org
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Alex Williamson -
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Tian, Kevin