powerpc: IOMMU fault injection

Add the ability to inject IOMMU faults. We enable this per device
via a fail_iommu sysfs property, similar to fault injection on other
subsystems.

An example:

...
0003:01:00.1 Ethernet controller: Emulex Corporation OneConnect 10Gb NIC (be3) (rev 02)

To inject one error to this device:

echo 1 > /sys/bus/pci/devices/0003:01:00.1/fail_iommu
echo 1 > /sys/kernel/debug/fail_iommu/probability
echo 1 > /sys/kernel/debug/fail_iommu/times

As feared, the first failure injected on the be3 results in an
unrecoverable error, taking down both functions of the card
permanently:

be2net 0003:01:00.1: Unrecoverable error in the card

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 9 insertions, 0 deletions

diff --git a/arch/powerpc/Kconfig.debug b/arch/powerpc/Kconfig.debug
index e5f26890a69e..5416e28a7538 100644
--- a/arch/powerpc/Kconfig.debug
+++ b/arch/powerpc/Kconfig.debug
@@ -331,4 +331,13 @@ config STRICT_DEVMEM
 
           If you are unsure, say Y.
 
+config FAIL_IOMMU
+        bool "Fault-injection capability for IOMMU"
+        depends on FAULT_INJECTION
+        help
+          Provide fault-injection capability for IOMMU. Each device can
+          be selectively enabled via the fail_iommu property.
+
+          If you are unsure, say N.
+
 endmenu