1 files changed, 109 insertions, 0 deletions
diff --git a/drivers/iommu/iommufd/io_pagetable.h b/drivers/iommu/iommufd/io_pagetable.h
new file mode 100644
index 000000000000..b74bf01ffc52
--- /dev/null
+++ b/drivers/iommu/iommufd/io_pagetable.h
@@ -0,0 +1,109 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* Copyright (c) 2021-2022, NVIDIA CORPORATION & AFFILIATES.
+ *
+ */
+#ifndef __IO_PAGETABLE_H
+#define __IO_PAGETABLE_H
+
+#include <linux/interval_tree.h>
+#include <linux/mutex.h>
+#include <linux/kref.h>
+#include <linux/xarray.h>
+
+#include "iommufd_private.h"
+
+struct iommu_domain;
+
+/*
+ * Each io_pagetable is composed of intervals of areas which cover regions of
+ * the iova that are backed by something. iova not covered by areas is not
+ * populated in the page table. Each area is fully populated with pages.
+ *
+ * iovas are in byte units, but must be iopt->iova_alignment aligned.
+ *
+ * pages can be NULL, this means some other thread is still working on setting
+ * up or tearing down the area. When observed under the write side of the
+ * domain_rwsem a NULL pages must mean the area is still being setup and no
+ * domains are filled.
+ *
+ * storage_domain points at an arbitrary iommu_domain that is holding the PFNs
+ * for this area. It is locked by the pages->mutex. This simplifies the locking
+ * as the pages code can rely on the storage_domain without having to get the
+ * iopt->domains_rwsem.
+ *
+ * The io_pagetable::iova_rwsem protects node
+ * The iopt_pages::mutex protects pages_node
+ * iopt and immu_prot are immutable
+ * The pages::mutex protects num_accesses
+ */
+struct iopt_area {
+	struct interval_tree_node node;
+	struct interval_tree_node pages_node;
+	struct io_pagetable *iopt;
+	struct iopt_pages *pages;
+	struct iommu_domain *storage_domain;
+	/* How many bytes into the first page the area starts */
+	unsigned int page_offset;
+	/* IOMMU_READ, IOMMU_WRITE, etc */
+	int iommu_prot;
+	unsigned int num_accesses;
+};
+
+static inline unsigned long iopt_area_index(struct iopt_area *area)
+{
+	return area->pages_node.start;
+}
+
+static inline unsigned long iopt_area_last_index(struct iopt_area *area)
+{
+	return area->pages_node.last;
+}
+
+static inline unsigned long iopt_area_iova(struct iopt_area *area)
+{
+	return area->node.start;
+}
+
+static inline unsigned long iopt_area_last_iova(struct iopt_area *area)
+{
+	return area->node.last;
+}
+
+enum {
+	IOPT_PAGES_ACCOUNT_NONE = 0,
+	IOPT_PAGES_ACCOUNT_USER = 1,
+	IOPT_PAGES_ACCOUNT_MM = 2,
+};
+
+/*
+ * This holds a pinned page list for multiple areas of IO address space. The
+ * pages always originate from a linear chunk of userspace VA. Multiple
+ * io_pagetable's, through their iopt_area's, can share a single iopt_pages
+ * which avoids multi-pinning and double accounting of page consumption.
+ *
+ * indexes in this structure are measured in PAGE_SIZE units, are 0 based from
+ * the start of the uptr and extend to npages. pages are pinned dynamically
+ * according to the intervals in the access_itree and domains_itree, npinned
+ * records the current number of pages pinned.
+ */
+struct iopt_pages {
+	struct kref kref;
+	struct mutex mutex;
+	size_t npages;
+	size_t npinned;
+	size_t last_npinned;
+	struct task_struct *source_task;
+	struct mm_struct *source_mm;
+	struct user_struct *source_user;
+	void __user *uptr;
+	bool writable:1;
+	u8 account_mode;
+
+	struct xarray pinned_pfns;
+	/* Of iopt_pages_access::node */
+	struct rb_root_cached access_itree;
+	/* Of iopt_area::pages_node */
+	struct rb_root_cached domains_itree;
+};
+
+#endif