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Commit d6b9a81b authored by Anton Blanchard's avatar Anton Blanchard Committed by Benjamin Herrenschmidt
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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: default avatarAnton Blanchard <anton@samba.org>
Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
parent a9803497

arch/powerpc/Kconfig.debug

+9 −0
Original line number Diff line number Diff line
@@ -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

arch/powerpc/include/asm/device.h

+3 −0
Original line number Diff line number Diff line
@@ -34,6 +34,9 @@ struct dev_archdata { 
#ifdef CONFIG_EEH

	struct eeh_dev		*edev;

#endif

#ifdef CONFIG_FAIL_IOMMU

	int fail_iommu;

#endif

};



struct pdev_archdata {

arch/powerpc/kernel/iommu.c

+94 −0
Original line number Diff line number Diff line
@@ -34,6 +34,8 @@ 
#include <linux/iommu-helper.h>

#include <linux/crash_dump.h>

#include <linux/hash.h>

#include <linux/fault-inject.h>

#include <linux/pci.h>

#include <asm/io.h>

#include <asm/prom.h>

#include <asm/iommu.h>
@@ -41,6 +43,7 @@ 
#include <asm/machdep.h>

#include <asm/kdump.h>

#include <asm/fadump.h>

#include <asm/vio.h>



#define DBG(...)
@@ -79,6 +82,94 @@ static int __init setup_iommu_pool_hash(void) 
}

subsys_initcall(setup_iommu_pool_hash);



#ifdef CONFIG_FAIL_IOMMU



static DECLARE_FAULT_ATTR(fail_iommu);



static int __init setup_fail_iommu(char *str)

{

	return setup_fault_attr(&fail_iommu, str);

}

__setup("fail_iommu=", setup_fail_iommu);



static bool should_fail_iommu(struct device *dev)

{

	return dev->archdata.fail_iommu && should_fail(&fail_iommu, 1);

}



static int __init fail_iommu_debugfs(void)

{

	struct dentry *dir = fault_create_debugfs_attr("fail_iommu",

						       NULL, &fail_iommu);



	return IS_ERR(dir) ? PTR_ERR(dir) : 0;

}

late_initcall(fail_iommu_debugfs);



static ssize_t fail_iommu_show(struct device *dev,

			       struct device_attribute *attr, char *buf)

{

	return sprintf(buf, "%d\n", dev->archdata.fail_iommu);

}



static ssize_t fail_iommu_store(struct device *dev,

				struct device_attribute *attr, const char *buf,

				size_t count)

{

	int i;



	if (count > 0 && sscanf(buf, "%d", &i) > 0)

		dev->archdata.fail_iommu = (i == 0) ? 0 : 1;



	return count;

}



static DEVICE_ATTR(fail_iommu, S_IRUGO|S_IWUSR, fail_iommu_show,

		   fail_iommu_store);



static int fail_iommu_bus_notify(struct notifier_block *nb,

				 unsigned long action, void *data)

{

	struct device *dev = data;



	if (action == BUS_NOTIFY_ADD_DEVICE) {

		if (device_create_file(dev, &dev_attr_fail_iommu))

			pr_warn("Unable to create IOMMU fault injection sysfs "

				"entries\n");

	} else if (action == BUS_NOTIFY_DEL_DEVICE) {

		device_remove_file(dev, &dev_attr_fail_iommu);

	}



	return 0;

}



static struct notifier_block fail_iommu_bus_notifier = {

	.notifier_call = fail_iommu_bus_notify

};



static int __init fail_iommu_setup(void)

{

#ifdef CONFIG_PCI

	bus_register_notifier(&pci_bus_type, &fail_iommu_bus_notifier);

#endif

#ifdef CONFIG_IBMVIO

	bus_register_notifier(&vio_bus_type, &fail_iommu_bus_notifier);

#endif



	return 0;

}

/*

 * Must execute after PCI and VIO subsystem have initialised but before

 * devices are probed.

 */

arch_initcall(fail_iommu_setup);

#else

static inline bool should_fail_iommu(struct device *dev)

{

	return false;

}

#endif



static unsigned long iommu_range_alloc(struct device *dev,

				       struct iommu_table *tbl,

                                       unsigned long npages,
@@ -107,6 +198,9 @@ static unsigned long iommu_range_alloc(struct device *dev, 
		return DMA_ERROR_CODE;

	}



	if (should_fail_iommu(dev))

		return DMA_ERROR_CODE;



	/*

	 * We don't need to disable preemption here because any CPU can

	 * safely use any IOMMU pool.