[PATCH v7 15/15] PCI: Allocate 64-bit BARs above 4G when possible

[Bjorn Helgaas]

From: Yinghai Lu <yinghai@xxxxxxxxxx>

Try to allocate space for 64-bit BARs above 4G first, to preserve the space
below 4G for 32-bit BARs.  If there's no space above 4G available, fall
back to allocating anywhere.

[bhelgaas: reworked starting from http://lkml.kernel.org/r/1387485843-17403-2-git-send-email-yinghai@xxxxxxxxxx]
Signed-off-by: Yinghai Lu <yinghai@xxxxxxxxxx>
Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
---
 drivers/pci/bus.c |   16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/drivers/pci/bus.c b/drivers/pci/bus.c
index 58beaaba50ee..107ad9a5b8aa 100644
--- a/drivers/pci/bus.c
+++ b/drivers/pci/bus.c
@@ -101,6 +101,8 @@ void pci_bus_remove_resources(struct pci_bus *bus)
 static struct pci_bus_region pci_32_bit = {0, 0xffffffffULL};
 static struct pci_bus_region pci_64_bit = {0,
 				(resource_size_t) 0xffffffffffffffffULL};
+static struct pci_bus_region pci_high = {(resource_size_t) 0x100000000ULL,
+				(resource_size_t) 0xffffffffffffffffULL};
 
 /*
  * @res contains CPU addresses.  Clip it so the corresponding bus addresses
@@ -196,8 +198,7 @@ static int pci_bus_alloc_from_region(struct pci_bus *bus, struct resource *res,
  * alignment and type, try to find an acceptable resource allocation
  * for a specific device resource.
  */
-int
-pci_bus_alloc_resource(struct pci_bus *bus, struct resource *res,
+int pci_bus_alloc_resource(struct pci_bus *bus, struct resource *res,
 		resource_size_t size, resource_size_t align,
 		resource_size_t min, unsigned int type_mask,
 		resource_size_t (*alignf)(void *,
@@ -206,10 +207,19 @@ pci_bus_alloc_resource(struct pci_bus *bus, struct resource *res,
 					  resource_size_t),
 		void *alignf_data)
 {
-	if (res->flags & IORESOURCE_MEM_64)
+	int rc;
+
+	if (res->flags & IORESOURCE_MEM_64) {
+		rc = pci_bus_alloc_from_region(bus, res, size, align, min,
+					       type_mask, alignf, alignf_data,
+					       &pci_high);
+		if (rc == 0)
+			return 0;
+
 		return pci_bus_alloc_from_region(bus, res, size, align, min,
 						 type_mask, alignf, alignf_data,
 						 &pci_64_bit);
+	}
 
 	return pci_bus_alloc_from_region(bus, res, size, align, min,
 					 type_mask, alignf, alignf_data,

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