[PATCH v4 2/2] iommu: Change iommu driver to call io_page_fault trace event

[Shuah Khan]

Change iommu driver call io_page_fault trace event. This iommu_error class
event can be enabled to trigger when an iommu error occurs. Trace information
includes driver name, device name, iova, and flags.

Testing:
Added trace calls to iommu_prepare_identity_map() for testing some of the
conditions that are hard to trigger. Here is the trace from the testing:

       swapper/0-1     [003] ....     2.003774: io_page_fault: IOMMU:pci 0000:00:02.0 iova=0x00000000cb800000 flags=0x0002
       swapper/0-1     [003] ....     2.004098: io_page_fault: IOMMU:pci 0000:00:1d.0 iova=0x00000000cadc6000 flags=0x0002
       swapper/0-1     [003] ....     2.004115: io_page_fault: IOMMU:pci 0000:00:1a.0 iova=0x00000000cadc6000 flags=0x0002
       swapper/0-1     [003] ....     2.004129: io_page_fault: IOMMU:pci 0000:00:1f.0 iova=0x0000000000000000 flags=0x0002

Signed-off-by: Shuah Khan <shuah.kh@xxxxxxxxxxx>
---
 include/linux/iommu.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 7ea319e..a444c79 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -22,6 +22,7 @@
 #include <linux/errno.h>
 #include <linux/err.h>
 #include <linux/types.h>
+#include <trace/events/iommu.h>
 
 #define IOMMU_READ	(1)
 #define IOMMU_WRITE	(2)
@@ -227,6 +228,7 @@ static inline int report_iommu_fault(struct iommu_domain *domain,
 		ret = domain->handler(domain, dev, iova, flags,
 						domain->handler_token);
 
+	trace_io_page_fault(dev, iova, flags);
 	return ret;
 }
 
-- 
1.8.1.2

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