[PATCH 16/37] iommu: Add generic PASID table library

[Jean-Philippe Brucker <jean-philippe.brucker-5wv7dgnIgG8@public.gmane.org>]

Add a small API within the IOMMU subsystem to handle different formats of
PASID tables. It uses the same principle as io-pgtable:

* The IOMMU driver registers a PASID table with some invalidation
  callbacks.
* The pasid-table lib allocates a set of tables of the right format, and
  returns an iommu_pasid_table_ops structure.
* The IOMMU driver allocates entries and writes them using the provided
  ops.
* The pasid-table lib calls the IOMMU driver back for invalidation when
  necessary.
* The IOMMU driver unregisters the ops which frees the tables when
  finished.

An example user will be Arm SMMU in a subsequent patch.

Signed-off-by: Jean-Philippe Brucker <jean-philippe.brucker-5wv7dgnIgG8@public.gmane.org>
---
 drivers/iommu/Kconfig       |   8 +++
 drivers/iommu/Makefile      |   1 +
 drivers/iommu/iommu-pasid.c |  53 +++++++++++++++++
 drivers/iommu/iommu-pasid.h | 142 ++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 204 insertions(+)
 create mode 100644 drivers/iommu/iommu-pasid.c
 create mode 100644 drivers/iommu/iommu-pasid.h

diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
index e751bb9958ba..8add90ba9b75 100644
--- a/drivers/iommu/Kconfig
+++ b/drivers/iommu/Kconfig
@@ -60,6 +60,14 @@ config IOMMU_IO_PGTABLE_ARMV7S_SELFTEST
 
 endmenu
 
+menu "Generic PASID table support"
+
+# Selected by the actual PASID table implementations
+config IOMMU_PASID_TABLE
+	bool
+
+endmenu
+
 config IOMMU_IOVA
 	tristate
 
diff --git a/drivers/iommu/Makefile b/drivers/iommu/Makefile
index f4324e29035e..338e59c93131 100644
--- a/drivers/iommu/Makefile
+++ b/drivers/iommu/Makefile
@@ -8,6 +8,7 @@ obj-$(CONFIG_IOMMU_FAULT) += io-pgfault.o
 obj-$(CONFIG_IOMMU_IO_PGTABLE) += io-pgtable.o
 obj-$(CONFIG_IOMMU_IO_PGTABLE_ARMV7S) += io-pgtable-arm-v7s.o
 obj-$(CONFIG_IOMMU_IO_PGTABLE_LPAE) += io-pgtable-arm.o
+obj-$(CONFIG_IOMMU_PASID_TABLE) += iommu-pasid.o
 obj-$(CONFIG_IOMMU_IOVA) += iova.o
 obj-$(CONFIG_OF_IOMMU)	+= of_iommu.o
 obj-$(CONFIG_MSM_IOMMU) += msm_iommu.o
diff --git a/drivers/iommu/iommu-pasid.c b/drivers/iommu/iommu-pasid.c
new file mode 100644
index 000000000000..6b21d369d514
--- /dev/null
+++ b/drivers/iommu/iommu-pasid.c
@@ -0,0 +1,53 @@
+/*
+ * PASID table management for the IOMMU
+ *
+ * Copyright (C) 2018 ARM Ltd.
+ * Author: Jean-Philippe Brucker <jean-philippe.brucker-5wv7dgnIgG8@public.gmane.org>
+ *
+ * SPDX-License-Identifier: GPL-2.0
+ */
+
+#include <linux/kernel.h>
+
+#include "iommu-pasid.h"
+
+static const struct iommu_pasid_init_fns *
+pasid_table_init_fns[PASID_TABLE_NUM_FMTS] = {
+};
+
+struct iommu_pasid_table_ops *
+iommu_alloc_pasid_ops(enum iommu_pasid_table_fmt fmt,
+		      struct iommu_pasid_table_cfg *cfg, void *cookie)
+{
+	struct iommu_pasid_table *table;
+	const struct iommu_pasid_init_fns *fns;
+
+	if (fmt >= PASID_TABLE_NUM_FMTS)
+		return NULL;
+
+	fns = pasid_table_init_fns[fmt];
+	if (!fns)
+		return NULL;
+
+	table = fns->alloc(cfg, cookie);
+	if (!table)
+		return NULL;
+
+	table->fmt = fmt;
+	table->cookie = cookie;
+	table->cfg = *cfg;
+
+	return &table->ops;
+}
+
+void iommu_free_pasid_ops(struct iommu_pasid_table_ops *ops)
+{
+	struct iommu_pasid_table *table;
+
+	if (!ops)
+		return;
+
+	table = container_of(ops, struct iommu_pasid_table, ops);
+	iommu_pasid_flush_all(table);
+	pasid_table_init_fns[table->fmt]->free(table);
+}
diff --git a/drivers/iommu/iommu-pasid.h b/drivers/iommu/iommu-pasid.h
new file mode 100644
index 000000000000..40a27d35c1e0
--- /dev/null
+++ b/drivers/iommu/iommu-pasid.h
@@ -0,0 +1,142 @@
+/*
+ * PASID table management for the IOMMU
+ *
+ * Copyright (C) 2017 ARM Ltd.
+ * Author: Jean-Philippe Brucker <jean-philippe.brucker-5wv7dgnIgG8@public.gmane.org>
+ *
+ * SPDX-License-Identifier: GPL-2.0
+ */
+#ifndef __IOMMU_PASID_H
+#define __IOMMU_PASID_H
+
+#include <linux/types.h>
+#include "io-pgtable.h"
+
+struct mm_struct;
+
+enum iommu_pasid_table_fmt {
+	PASID_TABLE_NUM_FMTS,
+};
+
+/**
+ * iommu_pasid_entry - Entry of a PASID table
+ *
+ * @token:	architecture-specific data needed to uniquely identify the
+ *		entry. Most notably used for TLB invalidation
+ */
+struct iommu_pasid_entry {
+	u64		tag;
+};
+
+/**
+ * iommu_pasid_table_ops - Operations on a PASID table
+ *
+ * @alloc_shared_entry:	allocate an entry for sharing an mm (SVA)
+ *			Returns the pointer to a new entry or an error
+ * @alloc_priv_entry:	allocate an entry for map/unmap operations
+ *			Returns the pointer to a new entry or an error
+ * @free_entry:		free an entry obtained with alloc_entry
+ * @set_entry:		write PASID table entry
+ * @clear_entry:	clear PASID table entry
+ */
+struct iommu_pasid_table_ops {
+	struct iommu_pasid_entry *
+	(*alloc_shared_entry)(struct iommu_pasid_table_ops *ops,
+			      struct mm_struct *mm);
+	struct iommu_pasid_entry *
+	(*alloc_priv_entry)(struct iommu_pasid_table_ops *ops,
+			    enum io_pgtable_fmt fmt,
+			    struct io_pgtable_cfg *cfg);
+	void (*free_entry)(struct iommu_pasid_table_ops *ops,
+			   struct iommu_pasid_entry *entry);
+	int (*set_entry)(struct iommu_pasid_table_ops *ops, int pasid,
+			 struct iommu_pasid_entry *entry);
+	void (*clear_entry)(struct iommu_pasid_table_ops *ops, int pasid,
+			    struct iommu_pasid_entry *entry);
+};
+
+/**
+ * iommu_pasid_sync_ops - Callbacks into the IOMMU driver
+ *
+ * @cfg_flush:		flush cached configuration for one entry. For a
+ *			multi-level PASID table, 'leaf' tells whether to only
+ *			flush cached leaf entries or intermediate levels as
+ *			well.
+ * @cfg_flush_all:	flush cached configuration for all entries of the PASID
+ *			table
+ * @tlb_flush:		flush TLB entries for one entry
+ */
+struct iommu_pasid_sync_ops {
+	void (*cfg_flush)(void *cookie, int pasid, bool leaf);
+	void (*cfg_flush_all)(void *cookie);
+	void (*tlb_flush)(void *cookie, int pasid,
+			  struct iommu_pasid_entry *entry);
+};
+
+/**
+ * struct iommu_pasid_table_cfg - Configuration data for a set of PASID tables.
+ *
+ * @iommu_dev	device performing the DMA table walks
+ * @order:	number of PASID bits, set by IOMMU driver
+ * @flush:	TLB management callbacks for this set of tables.
+ *
+ * @base:	DMA address of the allocated table, set by the allocator.
+ */
+struct iommu_pasid_table_cfg {
+	struct device			*iommu_dev;
+	size_t				order;
+	const struct iommu_pasid_sync_ops *sync;
+
+	dma_addr_t			base;
+};
+
+struct iommu_pasid_table_ops *
+iommu_alloc_pasid_ops(enum iommu_pasid_table_fmt fmt,
+		      struct iommu_pasid_table_cfg *cfg,
+		      void *cookie);
+void iommu_free_pasid_ops(struct iommu_pasid_table_ops *ops);
+
+/**
+ * struct iommu_pasid_table - describes a set of PASID tables
+ *
+ * @fmt:	The PASID table format.
+ * @cookie:	An opaque token provided by the IOMMU driver and passed back to
+ *		any callback routine.
+ * @cfg:	A copy of the PASID table configuration.
+ * @ops:	The PASID table operations in use for this set of page tables.
+ */
+struct iommu_pasid_table {
+	enum iommu_pasid_table_fmt	fmt;
+	void				*cookie;
+	struct iommu_pasid_table_cfg	cfg;
+	struct iommu_pasid_table_ops	ops;
+};
+
+#define iommu_pasid_table_ops_to_table(ops) \
+	container_of((ops), struct iommu_pasid_table, ops)
+
+struct iommu_pasid_init_fns {
+	struct iommu_pasid_table *(*alloc)(struct iommu_pasid_table_cfg *cfg,
+					   void *cookie);
+	void (*free)(struct iommu_pasid_table *table);
+};
+
+static inline void iommu_pasid_flush_all(struct iommu_pasid_table *table)
+{
+	table->cfg.sync->cfg_flush_all(table->cookie);
+}
+
+static inline void iommu_pasid_flush(struct iommu_pasid_table *table,
+					 int pasid, bool leaf)
+{
+	table->cfg.sync->cfg_flush(table->cookie, pasid, leaf);
+}
+
+static inline void iommu_pasid_flush_tlbs(struct iommu_pasid_table *table,
+					  int pasid,
+					  struct iommu_pasid_entry *entry)
+{
+	table->cfg.sync->tlb_flush(table->cookie, pasid, entry);
+}
+
+#endif /* __IOMMU_PASID_H */
-- 
2.15.1

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