From: Scott Moser <smoser@redhat.com>
Subject: [PATCH RHEL5.1] bz242937 [ppc] Cope with PCI host bridge I/O window 	not starting at 0
Date: Thu, 26 Jul 2007 15:26:25 -0400 (EDT)
Bugzilla: 242937
Message-Id: <Pine.LNX.4.64.0707261525080.30310@squad5-lp1.lab.boston.redhat.com>
Changelog: [ppc] Cope with PCI host bridge I/O window not starting at 0


Reposting with correct bug in subject.

RHBZ#: 242937
------
https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=242937

Description:
------------
Currently our code to set up the data structures for a PCI host bridge and
create the mapping for its I/O window assumes that the window starts at I/O
port 0 on the PCI side.  If this is not true, we can end up with I/O port
numbers in the resources for PCI devices which will cause an oops if a driver
tries to access them via inb/outb etc., because there is no mapping for the
corresponding addresses.

Normally the I/O window starts at 0, but there are some situations on
partitioned machines with a hypervisor where the window may not start
at 0.

Certain Intel e1000 chips require special reset using port I/O. The ports
are not correctly mapped in ppc64. Although the bug was found in e1000
tests, the problem is not limited to legacy ethernet adapters. It will hit
every I/O adapter using port I/O.  In the e1000 case, the result is kernel
oops.

RHEL Version Found:
-------------------
This is a bug found in RHEL5u1 kernel 2.6.18-36.el5.

Upstream Status:
----------------
This patch is a combination of the following upstream git commits:
  11fbb00c67e19737757e747ec7dd3ba8d584f5d1
  31e92e0a1f40ecbef415cd99dc886b14963dc594


Test Status:
------------
To ensure cross-platform build, this code has been built with brew
--scratch against a 2.6.18-36.el5 kernel and is available at [1].

This kernel build was verified by Ryan Hong of IBM.  A e1000 device that was
would cause kernel oops without the patch was successfully used with this
patched kernel.

Proposed Patch:
----------------
Please review and ACK for RHEL5.1

-- 
[1] http://brewweb.devel.redhat.com/brew/taskinfo?taskID=887483

---
Index: linux-2.6.18.ppc64/arch/powerpc/kernel/pci_64.c
===================================================================
--- linux-2.6.18.ppc64.orig/arch/powerpc/kernel/pci_64.c
+++ linux-2.6.18.ppc64/arch/powerpc/kernel/pci_64.c
@@ -1031,8 +1031,9 @@ void __devinit pci_process_bridge_OF_ran
 
 		switch ((pci_space >> 24) & 0x3) {
 		case 1:		/* I/O space */
-			hose->io_base_phys = cpu_phys_addr;
-			hose->pci_io_size = size;
+			hose->io_base_phys = cpu_phys_addr - pci_addr;
+			/* handle from 0 to top of I/O window */
+			hose->pci_io_size = pci_addr + size;
 
 			res = &hose->io_resource;
 			res->flags = IORESOURCE_IO;
@@ -1122,35 +1123,24 @@ static int get_bus_io_range(struct pci_b
 				unsigned long *start_virt, unsigned long *size)
 {
 	struct pci_controller *hose = pci_bus_to_host(bus);
-	struct pci_bus_region region;
 	struct resource *res;
 
-	if (bus->self) {
+	if (bus->self)
 		res = bus->resource[0];
-		pcibios_resource_to_bus(bus->self, &region, res);
-		*start_phys = hose->io_base_phys + region.start;
-		*start_virt = (unsigned long) hose->io_base_virt + 
-				region.start;
-		if (region.end > region.start) 
-			*size = region.end - region.start + 1;
-		else {
-			printk("%s(): unexpected region 0x%lx->0x%lx\n", 
-					__FUNCTION__, region.start, region.end);
-			return 1;
-		}
-		
-	} else {
+	else
 		/* Root Bus */
 		res = &hose->io_resource;
-		*start_phys = hose->io_base_phys;
-		*start_virt = (unsigned long) hose->io_base_virt;
-		if (res->end > res->start)
-			*size = res->end - res->start + 1;
-		else {
-			printk("%s(): unexpected region 0x%lx->0x%lx\n", 
-					__FUNCTION__, res->start, res->end);
-			return 1;
-		}
+
+	*start_virt = pci_io_base + res->start;
+	*start_phys = *start_virt + hose->io_base_phys
+		- (unsigned long) hose->io_base_virt;
+
+	if (res->end > res->start)
+		*size = res->end - res->start + 1;
+	else {
+		printk("%s(): unexpected region 0x%lx->0x%lx\n", 
+			__FUNCTION__, res->start, res->end);
+		return 1;
 	}
 
 	return 0;