Merge branch 'pci/enumeration'

- Split out ARI "next function" handling from the traditional one (Niklas
  Schnelle)

- Move jailhouse "isolated function" (non-zero functions where function 0
  doesn't exist) handling to pci_scan_slot() to avoid duplicating
  multi-function scanning in pci_scan_child_bus_extend() (Niklas Schnelle)

- Extend "isolated function" probing to s390 (Niklas Schnelle).

- Allow s390 zPCI zbus without a function 0 (Niklas Schnelle)

* pci/enumeration:
  s390/pci: allow zPCI zbus without a function zero
  PCI: Extend isolated function probing to s390
  PCI: Move jailhouse's isolated function handling to pci_scan_slot()
  PCI: Split out next_ari_fn() from next_fn()
  PCI: Clean up pci_scan_slot()

1 files changed, 41 insertions, 46 deletions

diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 17a969942d37..4948531481d1 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -2579,33 +2579,39 @@ struct pci_dev *pci_scan_single_device(struct pci_bus *bus, int devfn)
 }
 EXPORT_SYMBOL(pci_scan_single_device);
 
-static unsigned int next_fn(struct pci_bus *bus, struct pci_dev *dev,
-			    unsigned int fn)
+static int next_ari_fn(struct pci_bus *bus, struct pci_dev *dev, int fn)
 {
 	int pos;
 	u16 cap = 0;
 	unsigned int next_fn;
 
-	if (pci_ari_enabled(bus)) {
-		if (!dev)
-			return 0;
-		pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_ARI);
-		if (!pos)
-			return 0;
+	if (!dev)
+		return -ENODEV;
 
-		pci_read_config_word(dev, pos + PCI_ARI_CAP, &cap);
-		next_fn = PCI_ARI_CAP_NFN(cap);
-		if (next_fn <= fn)
-			return 0;	/* protect against malformed list */
+	pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_ARI);
+	if (!pos)
+		return -ENODEV;
 
-		return next_fn;
-	}
+	pci_read_config_word(dev, pos + PCI_ARI_CAP, &cap);
+	next_fn = PCI_ARI_CAP_NFN(cap);
+	if (next_fn <= fn)
+		return -ENODEV;	/* protect against malformed list */
 
-	/* dev may be NULL for non-contiguous multifunction devices */
-	if (!dev || dev->multifunction)
-		return (fn + 1) % 8;
+	return next_fn;
+}
 
-	return 0;
+static int next_fn(struct pci_bus *bus, struct pci_dev *dev, int fn)
+{
+	if (pci_ari_enabled(bus))
+		return next_ari_fn(bus, dev, fn);
+
+	if (fn >= 7)
+		return -ENODEV;
+	/* only multifunction devices may have more functions */
+	if (dev && !dev->multifunction)
+		return -ENODEV;
+
+	return fn + 1;
 }
 
 static int only_one_child(struct pci_bus *bus)
@@ -2643,26 +2649,30 @@ static int only_one_child(struct pci_bus *bus)
  */
 int pci_scan_slot(struct pci_bus *bus, int devfn)
 {
-	unsigned int fn, nr = 0;
 	struct pci_dev *dev;
+	int fn = 0, nr = 0;
 
 	if (only_one_child(bus) && (devfn > 0))
 		return 0; /* Already scanned the entire slot */
 
-	dev = pci_scan_single_device(bus, devfn);
-	if (!dev)
-		return 0;
-	if (!pci_dev_is_added(dev))
-		nr++;
-
-	for (fn = next_fn(bus, dev, 0); fn > 0; fn = next_fn(bus, dev, fn)) {
+	do {
 		dev = pci_scan_single_device(bus, devfn + fn);
 		if (dev) {
 			if (!pci_dev_is_added(dev))
 				nr++;
-			dev->multifunction = 1;
+			if (fn > 0)
+				dev->multifunction = 1;
+		} else if (fn == 0) {
+			/*
+			 * Function 0 is required unless we are running on
+			 * a hypervisor that passes through individual PCI
+			 * functions.
+			 */
+			if (!hypervisor_isolated_pci_functions())
+				break;
 		}
-	}
+		fn = next_fn(bus, dev, fn);
+	} while (fn >= 0);
 
 	/* Only one slot has PCIe device */
 	if (bus->self && nr)
@@ -2858,29 +2868,14 @@ static unsigned int pci_scan_child_bus_extend(struct pci_bus *bus,
 {
 	unsigned int used_buses, normal_bridges = 0, hotplug_bridges = 0;
 	unsigned int start = bus->busn_res.start;
-	unsigned int devfn, fn, cmax, max = start;
+	unsigned int devfn, cmax, max = start;
 	struct pci_dev *dev;
-	int nr_devs;
 
 	dev_dbg(&bus->dev, "scanning bus\n");
 
 	/* Go find them, Rover! */
-	for (devfn = 0; devfn < 256; devfn += 8) {
-		nr_devs = pci_scan_slot(bus, devfn);
-
-		/*
-		 * The Jailhouse hypervisor may pass individual functions of a
-		 * multi-function device to a guest without passing function 0.
-		 * Look for them as well.
-		 */
-		if (jailhouse_paravirt() && nr_devs == 0) {
-			for (fn = 1; fn < 8; fn++) {
-				dev = pci_scan_single_device(bus, devfn + fn);
-				if (dev)
-					dev->multifunction = 1;
-			}
-		}
-	}
+	for (devfn = 0; devfn < 256; devfn += 8)
+		pci_scan_slot(bus, devfn);
 
 	/* Reserve buses for SR-IOV capability */
 	used_buses = pci_iov_bus_range(bus);