[PATCH] PCI: Block config access during BIST

Some PCI adapters (eg.  ipr scsi adapters) have an exposure today in that they
issue BIST to the adapter to reset the card.  If, during the time it takes to
complete BIST, userspace attempts to access PCI config space, the host bus
bridge will master abort the access since the ipr adapter does not respond on
the PCI bus for a brief period of time when running BIST.  On PPC64 hardware,
this master abort results in the host PCI bridge isolating that PCI device
from the rest of the system, making the device unusable until Linux is
rebooted.  This patch is an attempt to close that exposure by introducing some
blocking code in the PCI code.  When blocked, writes will be humored and reads
will return the cached value.  Ben Herrenschmidt has also mentioned that he
plans to use this in PPC power management.

Signed-off-by: Brian King <brking@us.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

 drivers/pci/access.c    |   89 ++++++++++++++++++++++++++++++++++++++++++++++++
 drivers/pci/pci-sysfs.c |   20 +++++-----
 drivers/pci/pci.h       |    7 +++
 drivers/pci/proc.c      |   28 +++++++--------
 drivers/pci/syscall.c   |   14 +++----
 include/linux/pci.h     |    7 +++
 6 files changed, 134 insertions(+), 31 deletions(-)

1 files changed, 7 insertions, 0 deletions

diff --git a/include/linux/pci.h b/include/linux/pci.h
index 7349058ed778..3596ac94ecff 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -132,6 +132,7 @@ struct pci_dev {
         unsigned int    is_enabled:1;   /* pci_enable_device has been called */
         unsigned int    is_busmaster:1; /* device is busmaster */
         unsigned int    no_msi:1;       /* device may not use msi */
+        unsigned int    block_ucfg_access:1;    /* userspace config space access is blocked */
 
         u32             saved_config_space[16]; /* config space saved at suspend time */
         struct bin_attribute *rom_attr; /* attribute descriptor for sysfs ROM entry */
@@ -490,6 +491,9 @@ extern void pci_disable_msix(struct pci_dev *dev);
 extern void msi_remove_pci_irq_vectors(struct pci_dev *dev);
 #endif
 
+extern void pci_block_user_cfg_access(struct pci_dev *dev);
+extern void pci_unblock_user_cfg_access(struct pci_dev *dev);
+
 /*
  * PCI domain support.  Sometimes called PCI segment (eg by ACPI),
  * a PCI domain is defined to be a set of PCI busses which share
@@ -560,6 +564,9 @@ static inline int pci_enable_wake(struct pci_dev *dev, pci_power_t state, int en
 
 #define pci_dma_burst_advice(pdev, strat, strategy_parameter) do { } while (0)
 
+static inline void pci_block_user_cfg_access(struct pci_dev *dev) { }
+static inline void pci_unblock_user_cfg_access(struct pci_dev *dev) { }
+
 #endif /* CONFIG_PCI */
 
 /* Include architecture-dependent settings and functions */