[PATCH v7 17/26] PCI: hotplug: Ignore the MEM BAR offsets from BIOS/bootloader

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

BAR allocation by BIOS/UEFI/bootloader/firmware may be non-optimal and
it may even clash with the kernel's BAR assignment algorithm.

For example, sometimes BIOS doesn't reserve space for SR-IOV BARs, and
this bridge window can neither extend (blocked by immovable BARs) nor
move (the device itself is immovable).

With this patch the kernel will use its own methods of BAR allocating
when possible, increasing the chances of successful boot and hotplug.

Signed-off-by: Sergei Miroshnichenko <s.miroshnichenko@yadro.com>
---
 drivers/pci/probe.c | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index bb584038d5b4..f8f643dac6d1 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -306,6 +306,14 @@ int __pci_read_base(struct pci_dev *dev, enum pci_bar_type type,
 			 pos, (unsigned long long)region.start);
 	}
 
+	if (pci_can_move_bars && res->start && !(res->flags & IORESOURCE_IO)) {
+		pci_warn(dev, "ignore the current offset of BAR %llx-%llx\n",
+			 l64, l64 + sz64 - 1);
+		res->start = 0;
+		res->end = sz64 - 1;
+		res->flags |= IORESOURCE_SIZEALIGN;
+	}
+
 	goto out;
 
 
@@ -528,8 +536,10 @@ void pci_read_bridge_bases(struct pci_bus *child)
 		child->resource[i] = &dev->resource[PCI_BRIDGE_RESOURCES+i];
 
 	pci_read_bridge_io(child);
-	pci_read_bridge_mmio(child);
-	pci_read_bridge_mmio_pref(child);
+	if (!pci_can_move_bars) {
+		pci_read_bridge_mmio(child);
+		pci_read_bridge_mmio_pref(child);
+	}
 
 	if (dev->transparent) {
 		pci_bus_for_each_resource(child->parent, res, i) {
@@ -2945,6 +2955,8 @@ int pci_host_probe(struct pci_host_bridge *bridge)
 		pci_bus_claim_resources(bus);
 	} else {
 		pci_bus_size_bridges(bus);
+		if (pci_can_move_bars)
+			pci_bus_update_realloc_range(bus);
 		pci_bus_assign_resources(bus);
 
 		list_for_each_entry(child, &bus->children, node)
-- 
2.24.1