[PATCH v2 02/19] iommu: introduce device fault data

[Jacob Pan <jacob.jun.pan-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>]

Device faults detected by IOMMU can be reported outside the IOMMU
subsystem for further processing. This patch introduces
a generic device fault data structure.

The fault can be either an unrecoverable fault or a page request,
also referred to as a recoverable fault.

We only care about non internal faults that are likely to be reported
to an external subsystem.

Signed-off-by: Jacob Pan <jacob.jun.pan-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
Signed-off-by: Jean-Philippe Brucker <jean-philippe.brucker-5wv7dgnIgG8@public.gmane.org>
Signed-off-by: Liu, Yi L <yi.l.liu-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
Signed-off-by: Ashok Raj <ashok.raj-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
Signed-off-by: Eric Auger <eric.auger-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>

---
v4 -> v5:
- simplified struct iommu_fault_event comment
- Moved IOMMU_FAULT_PERM outside of the struct
- Removed IOMMU_FAULT_PERM_INST
- s/IOMMU_FAULT_PAGE_REQUEST_PASID_PRESENT/
  IOMMU_FAULT_PAGE_REQUEST_PASID_VALID

v3 -> v4:
- use a union containing aither an unrecoverable fault or a page
  request message. Move the device private data in the page request
  structure. Reshuffle the fields and use flags.
- move fault perm attributes to the uapi
- remove a bunch of iommu_fault_reason enum values that were related
  to internal errors
---
 include/linux/iommu.h      |  44 +++++++++++++++++
 include/uapi/linux/iommu.h | 115 +++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 159 insertions(+)
 create mode 100644 include/uapi/linux/iommu.h

diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 480921d..810bde2 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -25,6 +25,7 @@
 #include <linux/errno.h>
 #include <linux/err.h>
 #include <linux/of.h>
+#include <uapi/linux/iommu.h>
 
 #define IOMMU_READ	(1 << 0)
 #define IOMMU_WRITE	(1 << 1)
@@ -49,6 +50,7 @@ struct device;
 struct iommu_domain;
 struct notifier_block;
 struct iommu_sva;
+struct iommu_fault_event;
 
 /* iommu fault flags */
 #define IOMMU_FAULT_READ	0x0
@@ -58,6 +60,7 @@ typedef int (*iommu_fault_handler_t)(struct iommu_domain *,
 			struct device *, unsigned long, int, void *);
 typedef int (*iommu_mm_exit_handler_t)(struct device *dev, struct iommu_sva *,
 				       void *);
+typedef int (*iommu_dev_fault_handler_t)(struct iommu_fault_event *, void *);
 
 struct iommu_domain_geometry {
 	dma_addr_t aperture_start; /* First address that can be mapped    */
@@ -301,6 +304,46 @@ struct iommu_device {
 	struct device *dev;
 };
 
+/**
+ * struct iommu_fault_event - Generic fault event
+ *
+ * Can represent recoverable faults such as a page requests or
+ * unrecoverable faults such as DMA or IRQ remapping faults.
+ *
+ * @fault: fault descriptor
+ * @iommu_private: used by the IOMMU driver for storing fault-specific
+ *                 data. Users should not modify this field before
+ *                 sending the fault response.
+ */
+struct iommu_fault_event {
+	struct iommu_fault fault;
+	u64 iommu_private;
+};
+
+/**
+ * struct iommu_fault_param - per-device IOMMU fault data
+ * @dev_fault_handler: Callback function to handle IOMMU faults at device level
+ * @data: handler private data
+ *
+ */
+struct iommu_fault_param {
+	iommu_dev_fault_handler_t handler;
+	void *data;
+};
+
+/**
+ * struct iommu_param - collection of per-device IOMMU data
+ *
+ * @fault_param: IOMMU detected device fault reporting data
+ *
+ * TODO: migrate other per device data pointers under iommu_dev_data, e.g.
+ *	struct iommu_group	*iommu_group;
+ *	struct iommu_fwspec	*iommu_fwspec;
+ */
+struct iommu_param {
+	struct iommu_fault_param *fault_param;
+};
+
 int  iommu_device_register(struct iommu_device *iommu);
 void iommu_device_unregister(struct iommu_device *iommu);
 int  iommu_device_sysfs_add(struct iommu_device *iommu,
@@ -500,6 +543,7 @@ struct iommu_ops {};
 struct iommu_group {};
 struct iommu_fwspec {};
 struct iommu_device {};
+struct iommu_fault_param {};
 
 static inline bool iommu_present(struct bus_type *bus)
 {
diff --git a/include/uapi/linux/iommu.h b/include/uapi/linux/iommu.h
new file mode 100644
index 0000000..edcc0dd
--- /dev/null
+++ b/include/uapi/linux/iommu.h
@@ -0,0 +1,115 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+/*
+ * IOMMU user API definitions
+ */
+
+#ifndef _UAPI_IOMMU_H
+#define _UAPI_IOMMU_H
+
+#include <linux/types.h>
+
+#define IOMMU_FAULT_PERM_WRITE	(1 << 0) /* write */
+#define IOMMU_FAULT_PERM_EXEC	(1 << 1) /* exec */
+#define IOMMU_FAULT_PERM_PRIV	(1 << 2) /* privileged */
+
+/*  Generic fault types, can be expanded IRQ remapping fault */
+enum iommu_fault_type {
+	IOMMU_FAULT_DMA_UNRECOV = 1,	/* unrecoverable fault */
+	IOMMU_FAULT_PAGE_REQ,		/* page request fault */
+};
+
+enum iommu_fault_reason {
+	IOMMU_FAULT_REASON_UNKNOWN = 0,
+
+	/* Could not access the PASID table (fetch caused external abort) */
+	IOMMU_FAULT_REASON_PASID_FETCH,
+
+	/* pasid entry is invalid or has configuration errors */
+	IOMMU_FAULT_REASON_BAD_PASID_ENTRY,
+
+	/*
+	 * PASID is out of range (e.g. exceeds the maximum PASID
+	 * supported by the IOMMU) or disabled.
+	 */
+	IOMMU_FAULT_REASON_PASID_INVALID,
+
+	/*
+	 * An external abort occurred fetching (or updating) a translation
+	 * table descriptor
+	 */
+	IOMMU_FAULT_REASON_WALK_EABT,
+
+	/*
+	 * Could not access the page table entry (Bad address),
+	 * actual translation fault
+	 */
+	IOMMU_FAULT_REASON_PTE_FETCH,
+
+	/* Protection flag check failed */
+	IOMMU_FAULT_REASON_PERMISSION,
+
+	/* access flag check failed */
+	IOMMU_FAULT_REASON_ACCESS,
+
+	/* Output address of a translation stage caused Address Size fault */
+	IOMMU_FAULT_REASON_OOR_ADDRESS,
+};
+
+/**
+ * Unrecoverable fault data
+ * @reason: reason of the fault
+ * @addr: offending page address
+ * @fetch_addr: address that caused a fetch abort, if any
+ * @pasid: contains process address space ID, used in shared virtual memory
+ * @perm: Requested permission access using by the incoming transaction
+ * (IOMMU_FAULT_PERM_* values)
+ */
+struct iommu_fault_unrecoverable {
+	__u32	reason; /* enum iommu_fault_reason */
+#define IOMMU_FAULT_UNRECOV_PASID_VALID		(1 << 0)
+#define IOMMU_FAULT_UNRECOV_PERM_VALID		(1 << 1)
+#define IOMMU_FAULT_UNRECOV_ADDR_VALID		(1 << 2)
+#define IOMMU_FAULT_UNRECOV_FETCH_ADDR_VALID	(1 << 3)
+	__u32	flags;
+	__u32	pasid;
+	__u32	perm;
+	__u64	addr;
+	__u64	fetch_addr;
+};
+
+/*
+ * Page Request data (aka. recoverable fault data)
+ * @flags : encodes whether the pasid is valid and whether this
+ * is the last page in group
+ * @pasid: pasid
+ * @grpid: page request group index
+ * @perm: requested page permissions (IOMMU_FAULT_PERM_* values)
+ * @addr: page address
+ */
+struct iommu_fault_page_request {
+#define IOMMU_FAULT_PAGE_REQUEST_PASID_VALID	(1 << 0)
+#define IOMMU_FAULT_PAGE_REQUEST_LAST_PAGE	(1 << 1)
+#define IOMMU_FAULT_PAGE_REQUEST_PRIV_DATA	(1 << 2)
+	__u32   flags;
+	__u32	pasid;
+	__u32	grpid;
+	__u32	perm;
+	__u64	addr;
+	__u64	private_data[2];
+};
+
+/**
+ * struct iommu_fault - Generic fault data
+ *
+ * @type contains fault type
+ */
+
+struct iommu_fault {
+	__u32	type;   /* enum iommu_fault_type */
+	__u32	reserved;
+	union {
+		struct iommu_fault_unrecoverable event;
+		struct iommu_fault_page_request prm;
+	};
+};
+#endif /* _UAPI_IOMMU_H */
-- 
2.7.4