Patch "PCI: Do not allocate more buses than available in parent" has been added to the 4.9-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    PCI: Do not allocate more buses than available in parent

to the 4.9-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     pci-do-not-allocate-more-buses-than-available-in-parent.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From foo@baz Mon Dec 18 14:12:34 CET 2017
From: Mika Westerberg <mika.westerberg@linux.intel.com>
Date: Fri, 13 Oct 2017 21:35:43 +0300
Subject: PCI: Do not allocate more buses than available in parent

From: Mika Westerberg <mika.westerberg@linux.intel.com>


[ Upstream commit a20c7f36bd3d20d245616ae223bb9d05dfb6f050 ]

One can ask more buses to be reserved for hotplug bridges by passing
pci=hpbussize=N in the kernel command line.  If the parent bus does not
have enough bus space available we incorrectly create child bus with the
requested number of subordinate buses.

In the example below hpbussize is set to one more than we have available
buses in the root port:

  pci 0000:07:00.0: [8086:1578] type 01 class 0x060400
  pci 0000:07:00.0: scanning [bus 00-00] behind bridge, pass 0
  pci 0000:07:00.0: bridge configuration invalid ([bus 00-00]), reconfiguring
  pci 0000:07:00.0: scanning [bus 00-00] behind bridge, pass 1
  pci_bus 0000:08: busn_res: can not insert [bus 08-ff] under [bus 07-3f] (conflicts with (null) [bus 07-3f])
  pci_bus 0000:08: scanning bus
  ...
  pci_bus 0000:0a: bus scan returning with max=40
  pci_bus 0000:0a: busn_res: [bus 0a-ff] end is updated to 40
  pci_bus 0000:0a: [bus 0a-40] partially hidden behind bridge 0000:07 [bus 07-3f]
  pci_bus 0000:08: bus scan returning with max=40
  pci_bus 0000:08: busn_res: [bus 08-ff] end is updated to 40

Instead of allowing this, limit the subordinate number to be less than or
equal the maximum subordinate number allocated for the parent bus (if it
has any).

Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
[bhelgaas: remove irrelevant dmesg messages]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/pci/probe.c |    7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -932,7 +932,8 @@ int pci_scan_bridge(struct pci_bus *bus,
 			child = pci_add_new_bus(bus, dev, max+1);
 			if (!child)
 				goto out;
-			pci_bus_insert_busn_res(child, max+1, 0xff);
+			pci_bus_insert_busn_res(child, max+1,
+						bus->busn_res.end);
 		}
 		max++;
 		buses = (buses & 0xff000000)
@@ -2136,6 +2137,10 @@ unsigned int pci_scan_child_bus(struct p
 	if (bus->self && bus->self->is_hotplug_bridge && pci_hotplug_bus_size) {
 		if (max - bus->busn_res.start < pci_hotplug_bus_size - 1)
 			max = bus->busn_res.start + pci_hotplug_bus_size - 1;
+
+		/* Do not allocate more buses than we have room left */
+		if (max > bus->busn_res.end)
+			max = bus->busn_res.end;
 	}
 
 	/*


Patches currently in stable-queue which might be from mika.westerberg@linux.intel.com are

queue-4.9/pci-do-not-allocate-more-buses-than-available-in-parent.patch