x86/PCI: config space accessor functions should not ignore the segment argument

Without this change, the majority of the raw PCI config space access
functions silently ignore a non-zero segment argument, which is
certainly wrong.

Apart from pci_direct_conf1, all other non-MMCFG access methods get
used only for non-extended accesses (i.e. assigned to raw_pci_ops
only). Consequently, with the way raw_pci_{read,write}() work, it would
be a coding error to call these functions with a non-zero segment (with
the current call flow this cannot happen afaict).

The access method 1 accessor, as it can be used for extended accesses
(on AMD systems) instead gets checks added for the passed in segment to
be zero. This would be the case when on such a system having multiple
PCI segments (don't know whether any exist in practice) MMCFG for some
reason is not usable, and method 1 gets selected for doing extended
accesses. Rather than accessing the wrong device's config space, the
function will now error out.

v2: Convert BUG_ON() to WARN_ON(), and extend description as per Ingo's
request.

Signed-off-by: Jan Beulich <jbeulich@novell.com>
Reviewed-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

1 files changed, 2 insertions, 0 deletions

diff --git a/arch/x86/pci/ce4100.c b/arch/x86/pci/ce4100.c
index 67858be4b52b..99176094500b 100644
--- a/arch/x86/pci/ce4100.c
+++ b/arch/x86/pci/ce4100.c
@@ -257,6 +257,7 @@ static int ce4100_conf_read(unsigned int seg, unsigned int bus,
 {
         int i;
 
+        WARN_ON(seg);
         if (bus == 1) {
                 for (i = 0; i < ARRAY_SIZE(bus1_fixups); i++) {
                         if (bus1_fixups[i].dev_func == devfn &&
@@ -282,6 +283,7 @@ static int ce4100_conf_write(unsigned int seg, unsigned int bus,
 {
         int i;
 
+        WARN_ON(seg);
         if (bus == 1) {
                 for (i = 0; i < ARRAY_SIZE(bus1_fixups); i++) {
                         if (bus1_fixups[i].dev_func == devfn &&