[Xen-changelog] Allow pciback to be placed into a permissive mode of operation whereby it allows

[Xen patchbot -unstable <patchbot-unstable@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User kaf24@xxxxxxxxxxxxxxxxxxxx
# Node ID 42a1f6ffd0e9567a04175f1899c033f6e1d4d2df
# Parent  aae274b4c1a739f70abf2dd1f3d7629bc37ccc6c
Allow pciback to be placed into a permissive mode of operation whereby it allows
PCI config writes to succeed by default. Currently this is the only way to allow
control of a device that has device-specific registers in the config space from
a driver domain.

echo Y >/sys/module/pciback/parameters/permissive

Signed-off-by: Keir Fraser <keir@xxxxxxxxxxxxx>

diff -r aae274b4c1a7 -r 42a1f6ffd0e9 
linux-2.6-xen-sparse/drivers/xen/pciback/conf_space.c
--- a/linux-2.6-xen-sparse/drivers/xen/pciback/conf_space.c     Wed Mar  8 
14:51:28 2006
+++ b/linux-2.6-xen-sparse/drivers/xen/pciback/conf_space.c     Wed Mar  8 
16:32:36 2006
@@ -13,6 +13,9 @@
 #include <linux/pci.h>
 #include "pciback.h"
 #include "conf_space.h"
+
+static int permissive = 0;
+module_param(permissive, bool, 0644);
 
 #define DEFINE_PCI_CONFIG(op,size,type)                                        
\
 int pciback_##op##_config_##size                                               
        \
@@ -198,7 +201,7 @@
 
 int pciback_config_write(struct pci_dev *dev, int offset, int size, u32 value)
 {
-       int err = 0;
+       int err = 0, handled = 0;
        struct pciback_dev_data *dev_data = pci_get_drvdata(dev);
        struct config_field_entry *cfg_entry;
        struct config_field *field;
@@ -233,6 +236,21 @@
                                              field_start - req_start);
 
                        err = conf_space_write(dev, cfg_entry, offset, tmp_val);
+                       handled = 1;
+               }
+       }
+
+       if (!handled && !err && permissive) {
+               switch (size) {
+               case 1:
+                       err = pci_write_config_byte(dev, offset, (u8)value);
+                       break;
+               case 2:
+                       err = pci_write_config_word(dev, offset, (u16)value);
+                       break;
+               case 4:
+                       err = pci_write_config_dword(dev, offset, (u32)value);
+                       break;
                }
        }
 

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