[PATCH RFC v3 11/21] PCI: Release and reassign the root bridge resources during rescan

[Sergey Miroshnichenko <s.miroshnichenko@xxxxxxxxx>]

When the movable BARs feature is enabled, don't rely on the memory gaps
reserved by the BIOS/bootloader/firmware, but instead rearrange the BARs
and bridge windows starting from the root.

Endpoint device's BARs, after being released, are resorted and written
back by the pci_assign_unassigned_root_bus_resources().

The last step of writing the recalculated windows to the bridges is done
by the new pci_setup_bridges() function.

Signed-off-by: Sergey Miroshnichenko <s.miroshnichenko@xxxxxxxxx>
---
 drivers/pci/pci.h       |  1 +
 drivers/pci/probe.c     | 22 ++++++++++++++++++++++
 drivers/pci/setup-bus.c | 11 ++++++++++-
 3 files changed, 33 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index 224d88634115..e06e8692a7b1 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -248,6 +248,7 @@ void __pci_bus_assign_resources(const struct pci_bus *bus,
 				struct list_head *realloc_head,
 				struct list_head *fail_head);
 bool pci_bus_clip_resource(struct pci_dev *dev, int idx);
+void pci_bus_release_root_bridge_resources(struct pci_bus *bus);
 
 void pci_reassigndev_resource_alignment(struct pci_dev *dev);
 void pci_disable_bridge_window(struct pci_dev *dev);
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 1f50eb556d28..de808ca28797 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -3223,6 +3223,25 @@ static void pci_bus_rescan_done(struct pci_bus *bus)
 	pm_runtime_put(&bus->dev);
 }
 
+static void pci_setup_bridges(struct pci_bus *bus)
+{
+	struct pci_dev *dev;
+
+	list_for_each_entry(dev, &bus->devices, bus_list) {
+		struct pci_bus *child;
+
+		if (!pci_dev_is_added(dev) || pci_dev_is_ignored(dev))
+			continue;
+
+		child = dev->subordinate;
+		if (child)
+			pci_setup_bridges(child);
+	}
+
+	if (bus->self)
+		pci_setup_bridge(bus);
+}
+
 /**
  * pci_rescan_bus - Scan a PCI bus for devices
  * @bus: PCI bus to scan
@@ -3245,8 +3264,11 @@ unsigned int pci_rescan_bus(struct pci_bus *bus)
 		pci_bus_rescan_prepare(root);
 
 		max = pci_scan_child_bus(root);
+
+		pci_bus_release_root_bridge_resources(root);
 		pci_assign_unassigned_root_bus_resources(root);
 
+		pci_setup_bridges(root);
 		pci_bus_rescan_done(root);
 	} else {
 		max = pci_scan_child_bus(bus);
diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
index b1eec758d2c1..07c6d9cc209f 100644
--- a/drivers/pci/setup-bus.c
+++ b/drivers/pci/setup-bus.c
@@ -1621,7 +1621,7 @@ static void pci_bridge_release_resources(struct pci_bus *bus,
 		pci_printk(KERN_DEBUG, dev, "resource %d %pR released\n",
 					PCI_BRIDGE_RESOURCES + idx, r);
 		/* keep the old size */
-		r->end = resource_size(r) - 1;
+		r->end = pci_movable_bars_enabled() ? 0 : (resource_size(r) - 1);
 		r->start = 0;
 		r->flags = 0;
 
@@ -1674,6 +1674,15 @@ static void pci_bus_release_bridge_resources(struct pci_bus *bus,
 		pci_bridge_release_resources(bus, type);
 }
 
+void pci_bus_release_root_bridge_resources(struct pci_bus *root_bus)
+{
+	pci_bus_release_bridge_resources(root_bus, IORESOURCE_IO, whole_subtree);
+	pci_bus_release_bridge_resources(root_bus, IORESOURCE_MEM, whole_subtree);
+	pci_bus_release_bridge_resources(root_bus,
+					 IORESOURCE_MEM_64 | IORESOURCE_PREFETCH,
+					 whole_subtree);
+}
+
 static void pci_bus_dump_res(struct pci_bus *bus)
 {
 	struct resource *res;
-- 
2.20.1