Merge branch 'pci/reset'

- Add sysfs 'reset_subordinate' to reset hierarchy below bridge (Keith
  Busch)

- Warn if we reset a running device where driver didn't register
  pci_error_handlers notification callbacks (Keith Busch)

* pci/reset:
  PCI: Warn if a running device is unaware of reset
  PCI: Add 'reset_subordinate' to reset hierarchy below bridge

Author: bjorn-helgaas

Documentation/ABI/testing/sysfs-bus-pci

@@ -163,6 +163,17 @@ Description:
 		will be present in sysfs.  Writing 1 to this file
 		will perform reset.
 
+What:		/sys/bus/pci/devices/.../reset_subordinate
+Date:		October 2024
+Contact:	linux-pci@vger.kernel.org
+Description:
+		This is visible only for bridge devices. If you want to reset
+		all devices attached through the subordinate bus of a specific
+		bridge device, writing 1 to this will try to do it.  This will
+		affect all devices attached to the system through this bridge
+		similiar to writing 1 to their individual "reset" file, so use
+		with caution.
+
 What:		/sys/bus/pci/devices/.../vpd
 Date:		February 2008
 Contact:	Ben Hutchings <bwh@kernel.org>

drivers/pci/pci-sysfs.c

@@ -521,6 +521,31 @@ static ssize_t bus_rescan_store(struct device *dev,
 static struct device_attribute dev_attr_bus_rescan = __ATTR(rescan, 0200, NULL,
 							    bus_rescan_store);
 
+static ssize_t reset_subordinate_store(struct device *dev,
+				struct device_attribute *attr,
+				const char *buf, size_t count)
+{
+	struct pci_dev *pdev = to_pci_dev(dev);
+	struct pci_bus *bus = pdev->subordinate;
+	unsigned long val;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	if (kstrtoul(buf, 0, &val) < 0)
+		return -EINVAL;
+
+	if (val) {
+		int ret = __pci_reset_bus(bus);
+
+		if (ret)
+			return ret;
+	}
+
+	return count;
+}
+static DEVICE_ATTR_WO(reset_subordinate);
+
 #if defined(CONFIG_PM) && defined(CONFIG_ACPI)
 static ssize_t d3cold_allowed_store(struct device *dev,
 				    struct device_attribute *attr,
@@ -625,6 +650,7 @@ static struct attribute *pci_dev_attrs[] = {
 static struct attribute *pci_bridge_attrs[] = {
 	&dev_attr_subordinate_bus_number.attr,
 	&dev_attr_secondary_bus_number.attr,
+	&dev_attr_reset_subordinate.attr,
 	NULL,
 };
 

drivers/pci/pci.c

@@ -5158,6 +5158,8 @@ static void pci_dev_save_and_disable(struct pci_dev *dev)
 	 */
 	if (err_handler && err_handler->reset_prepare)
 		err_handler->reset_prepare(dev);
+	else if (dev->driver)
+		pci_warn(dev, "resetting");
 
 	/*
 	 * Wake-up device prior to save.  PM registers default to D0 after
@@ -5191,6 +5193,8 @@ static void pci_dev_restore(struct pci_dev *dev)
 	 */
 	if (err_handler && err_handler->reset_done)
 		err_handler->reset_done(dev);
+	else if (dev->driver)
+		pci_warn(dev, "reset done");
 }
 
 /* dev->reset_methods[] is a 0-terminated list of indices into this array */
@@ -5880,7 +5884,7 @@ EXPORT_SYMBOL_GPL(pci_probe_reset_bus);
  *
  * Same as above except return -EAGAIN if the bus cannot be locked
  */
-static int __pci_reset_bus(struct pci_bus *bus)
+int __pci_reset_bus(struct pci_bus *bus)
 {
 	int rc;
 

drivers/pci/pci.h

@@ -104,6 +104,7 @@ bool pci_reset_supported(struct pci_dev *dev);
 void pci_init_reset_methods(struct pci_dev *dev);
 int pci_bridge_secondary_bus_reset(struct pci_dev *dev);
 int pci_bus_error_reset(struct pci_dev *dev);
+int __pci_reset_bus(struct pci_bus *bus);
 
 struct pci_cap_saved_data {
 	u16		cap_nr;