[PATCH v9 12/26] PCI: Make sure bridge windows include their fixed BARs

[Sergei Miroshnichenko <s.miroshnichenko@yadro.com>]

With enabled movable BARs, bridge windows are recalculated during each PCI
rescan. There may be fixed BARs below a bridge: these areas are represented
by the .fixed_range field in struct pci_bus.

When choosing a start address for a bridge window, it should be not just a
lowest possible address: this window must cover every underlying fixed BAR.

If a size of the bridge window is equal to its fixed range, it can only be
assigned to the start of this range. But if a bridge window size is larger,
its lowest possible address equals to (fixed_range.end - bus_size + 1).

Signed-off-by: Sergei Miroshnichenko <s.miroshnichenko@yadro.com>
---
 drivers/pci/bus.c       |  2 +-
 drivers/pci/setup-res.c | 30 ++++++++++++++++++++++++++++--
 2 files changed, 29 insertions(+), 3 deletions(-)

diff --git a/drivers/pci/bus.c b/drivers/pci/bus.c
index 3cef835b375f..c716210b62c5 100644
--- a/drivers/pci/bus.c
+++ b/drivers/pci/bus.c
@@ -192,7 +192,7 @@ static int pci_bus_alloc_from_region(struct pci_bus *bus, struct resource *res,
 		 * this is an already-configured bridge window, its start
 		 * overrides "min".
 		 */
-		if (avail.start)
+		if (min_used < avail.start)
 			min_used = avail.start;
 
 		max = avail.end;
diff --git a/drivers/pci/setup-res.c b/drivers/pci/setup-res.c
index 432f3b084f94..ee192e731119 100644
--- a/drivers/pci/setup-res.c
+++ b/drivers/pci/setup-res.c
@@ -247,11 +247,27 @@ static int __pci_assign_resource(struct pci_bus *bus, struct pci_dev *dev,
 		int resno, resource_size_t size, resource_size_t align)
 {
 	struct resource *res = dev->resource + resno;
+	struct resource *fixed_range = NULL;
 	resource_size_t min;
 	int ret;
 
 	min = (res->flags & IORESOURCE_IO) ? PCIBIOS_MIN_IO : PCIBIOS_MIN_MEM;
 
+	if (pci_can_move_bars && dev->subordinate && resno >= PCI_BRIDGE_RESOURCES) {
+		struct pci_bus *child_bus = dev->subordinate;
+		int win_no = resno - PCI_BRIDGE_RESOURCES;
+
+		fixed_range = &child_bus->fixed_range[win_no];
+		if (pci_fixed_range_valid(fixed_range)) {
+			if (size <= resource_size(fixed_range))
+				min = fixed_range->start;
+			else
+				min = fixed_range->end - size + 1;
+		} else {
+			fixed_range = NULL;
+		}
+	}
+
 	/*
 	 * First, try exact prefetching match.  Even if a 64-bit
 	 * prefetchable bridge window is below 4GB, we can't put a 32-bit
@@ -263,7 +279,7 @@ static int __pci_assign_resource(struct pci_bus *bus, struct pci_dev *dev,
 				     IORESOURCE_PREFETCH | IORESOURCE_MEM_64,
 				     pcibios_align_resource, dev);
 	if (ret == 0)
-		return 0;
+		goto check_fixed;
 
 	/*
 	 * If the prefetchable window is only 32 bits wide, we can put
@@ -275,7 +291,7 @@ static int __pci_assign_resource(struct pci_bus *bus, struct pci_dev *dev,
 					     IORESOURCE_PREFETCH,
 					     pcibios_align_resource, dev);
 		if (ret == 0)
-			return 0;
+			goto check_fixed;
 	}
 
 	/*
@@ -288,6 +304,16 @@ static int __pci_assign_resource(struct pci_bus *bus, struct pci_dev *dev,
 		ret = pci_bus_alloc_resource(bus, res, size, align, min, 0,
 					     pcibios_align_resource, dev);
 
+check_fixed:
+	if (ret == 0 && fixed_range &&
+	    (res->start > fixed_range->start ||
+	     res->end < fixed_range->end)) {
+		dev_err(&bus->dev, "fixed area %pR for %s doesn't fit in the allocated %pR",
+			fixed_range, dev_name(&dev->dev), res);
+		release_resource(res);
+		return -1;
+	}
+
 	return ret;
 }
 
-- 
2.24.1