1 files changed, 467 insertions, 0 deletions
diff --git a/arch/powerpc/mm/mmu_context_iommu.c b/arch/powerpc/mm/mmu_context_iommu.c
new file mode 100644
index 000000000..56c2234cc
--- /dev/null
+++ b/arch/powerpc/mm/mmu_context_iommu.c
@@ -0,0 +1,467 @@
+/*
+ *  IOMMU helpers in MMU context.
+ *
+ *  Copyright (C) 2015 IBM Corp. <aik@ozlabs.ru>
+ *
+ *  This program is free software; you can redistribute it and/or
+ *  modify it under the terms of the GNU General Public License
+ *  as published by the Free Software Foundation; either version
+ *  2 of the License, or (at your option) any later version.
+ *
+ */
+
+#include <linux/sched/signal.h>
+#include <linux/slab.h>
+#include <linux/rculist.h>
+#include <linux/vmalloc.h>
+#include <linux/mutex.h>
+#include <linux/migrate.h>
+#include <linux/hugetlb.h>
+#include <linux/swap.h>
+#include <linux/sizes.h>
+#include <asm/mmu_context.h>
+#include <asm/pte-walk.h>
+
+static DEFINE_MUTEX(mem_list_mutex);
+
+#define MM_IOMMU_TABLE_GROUP_PAGE_DIRTY	0x1
+#define MM_IOMMU_TABLE_GROUP_PAGE_MASK	~(SZ_4K - 1)
+
+struct mm_iommu_table_group_mem_t {
+	struct list_head next;
+	struct rcu_head rcu;
+	unsigned long used;
+	atomic64_t mapped;
+	unsigned int pageshift;
+	u64 ua;			/* userspace address */
+	u64 entries;		/* number of entries in hpas[] */
+	u64 *hpas;		/* vmalloc'ed */
+};
+
+static long mm_iommu_adjust_locked_vm(struct mm_struct *mm,
+		unsigned long npages, bool incr)
+{
+	long ret = 0, locked, lock_limit;
+
+	if (!npages)
+		return 0;
+
+	down_write(&mm->mmap_sem);
+
+	if (incr) {
+		locked = mm->locked_vm + npages;
+		lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
+		if (locked > lock_limit && !capable(CAP_IPC_LOCK))
+			ret = -ENOMEM;
+		else
+			mm->locked_vm += npages;
+	} else {
+		if (WARN_ON_ONCE(npages > mm->locked_vm))
+			npages = mm->locked_vm;
+		mm->locked_vm -= npages;
+	}
+
+	pr_debug("[%d] RLIMIT_MEMLOCK HASH64 %c%ld %ld/%ld\n",
+			current ? current->pid : 0,
+			incr ? '+' : '-',
+			npages << PAGE_SHIFT,
+			mm->locked_vm << PAGE_SHIFT,
+			rlimit(RLIMIT_MEMLOCK));
+	up_write(&mm->mmap_sem);
+
+	return ret;
+}
+
+bool mm_iommu_preregistered(struct mm_struct *mm)
+{
+	return !list_empty(&mm->context.iommu_group_mem_list);
+}
+EXPORT_SYMBOL_GPL(mm_iommu_preregistered);
+
+/*
+ * Taken from alloc_migrate_target with changes to remove CMA allocations
+ */
+struct page *new_iommu_non_cma_page(struct page *page, unsigned long private)
+{
+	gfp_t gfp_mask = GFP_USER;
+	struct page *new_page;
+
+	if (PageCompound(page))
+		return NULL;
+
+	if (PageHighMem(page))
+		gfp_mask |= __GFP_HIGHMEM;
+
+	/*
+	 * We don't want the allocation to force an OOM if possibe
+	 */
+	new_page = alloc_page(gfp_mask | __GFP_NORETRY | __GFP_NOWARN);
+	return new_page;
+}
+
+static int mm_iommu_move_page_from_cma(struct page *page)
+{
+	int ret = 0;
+	LIST_HEAD(cma_migrate_pages);
+
+	/* Ignore huge pages for now */
+	if (PageCompound(page))
+		return -EBUSY;
+
+	lru_add_drain();
+	ret = isolate_lru_page(page);
+	if (ret)
+		return ret;
+
+	list_add(&page->lru, &cma_migrate_pages);
+	put_page(page); /* Drop the gup reference */
+
+	ret = migrate_pages(&cma_migrate_pages, new_iommu_non_cma_page,
+				NULL, 0, MIGRATE_SYNC, MR_CONTIG_RANGE);
+	if (ret) {
+		if (!list_empty(&cma_migrate_pages))
+			putback_movable_pages(&cma_migrate_pages);
+	}
+
+	return 0;
+}
+
+long mm_iommu_get(struct mm_struct *mm, unsigned long ua, unsigned long entries,
+		struct mm_iommu_table_group_mem_t **pmem)
+{
+	struct mm_iommu_table_group_mem_t *mem;
+	long i, j, ret = 0, locked_entries = 0;
+	unsigned int pageshift;
+	unsigned long flags;
+	unsigned long cur_ua;
+	struct page *page = NULL;
+
+	mutex_lock(&mem_list_mutex);
+
+	list_for_each_entry_rcu(mem, &mm->context.iommu_group_mem_list,
+			next) {
+		if ((mem->ua == ua) && (mem->entries == entries)) {
+			++mem->used;
+			*pmem = mem;
+			goto unlock_exit;
+		}
+
+		/* Overlap? */
+		if ((mem->ua < (ua + (entries << PAGE_SHIFT))) &&
+				(ua < (mem->ua +
+				       (mem->entries << PAGE_SHIFT)))) {
+			ret = -EINVAL;
+			goto unlock_exit;
+		}
+
+	}
+
+	ret = mm_iommu_adjust_locked_vm(mm, entries, true);
+	if (ret)
+		goto unlock_exit;
+
+	locked_entries = entries;
+
+	mem = kzalloc(sizeof(*mem), GFP_KERNEL);
+	if (!mem) {
+		ret = -ENOMEM;
+		goto unlock_exit;
+	}
+
+	/*
+	 * For a starting point for a maximum page size calculation
+	 * we use @ua and @entries natural alignment to allow IOMMU pages
+	 * smaller than huge pages but still bigger than PAGE_SIZE.
+	 */
+	mem->pageshift = __ffs(ua | (entries << PAGE_SHIFT));
+	mem->hpas = vzalloc(array_size(entries, sizeof(mem->hpas[0])));
+	if (!mem->hpas) {
+		kfree(mem);
+		ret = -ENOMEM;
+		goto unlock_exit;
+	}
+
+	for (i = 0; i < entries; ++i) {
+		cur_ua = ua + (i << PAGE_SHIFT);
+		if (1 != get_user_pages_fast(cur_ua,
+					1/* pages */, 1/* iswrite */, &page)) {
+			ret = -EFAULT;
+			for (j = 0; j < i; ++j)
+				put_page(pfn_to_page(mem->hpas[j] >>
+						PAGE_SHIFT));
+			vfree(mem->hpas);
+			kfree(mem);
+			goto unlock_exit;
+		}
+		/*
+		 * If we get a page from the CMA zone, since we are going to
+		 * be pinning these entries, we might as well move them out
+		 * of the CMA zone if possible. NOTE: faulting in + migration
+		 * can be expensive. Batching can be considered later
+		 */
+		if (is_migrate_cma_page(page)) {
+			if (mm_iommu_move_page_from_cma(page))
+				goto populate;
+			if (1 != get_user_pages_fast(cur_ua,
+						1/* pages */, 1/* iswrite */,
+						&page)) {
+				ret = -EFAULT;
+				for (j = 0; j < i; ++j)
+					put_page(pfn_to_page(mem->hpas[j] >>
+								PAGE_SHIFT));
+				vfree(mem->hpas);
+				kfree(mem);
+				goto unlock_exit;
+			}
+		}
+populate:
+		pageshift = PAGE_SHIFT;
+		if (mem->pageshift > PAGE_SHIFT && PageCompound(page)) {
+			pte_t *pte;
+			struct page *head = compound_head(page);
+			unsigned int compshift = compound_order(head);
+			unsigned int pteshift;
+
+			local_irq_save(flags); /* disables as well */
+			pte = find_linux_pte(mm->pgd, cur_ua, NULL, &pteshift);
+
+			/* Double check it is still the same pinned page */
+			if (pte && pte_page(*pte) == head &&
+			    pteshift == compshift + PAGE_SHIFT)
+				pageshift = max_t(unsigned int, pteshift,
+						PAGE_SHIFT);
+			local_irq_restore(flags);
+		}
+		mem->pageshift = min(mem->pageshift, pageshift);
+		mem->hpas[i] = page_to_pfn(page) << PAGE_SHIFT;
+	}
+
+	atomic64_set(&mem->mapped, 1);
+	mem->used = 1;
+	mem->ua = ua;
+	mem->entries = entries;
+	*pmem = mem;
+
+	list_add_rcu(&mem->next, &mm->context.iommu_group_mem_list);
+
+unlock_exit:
+	if (locked_entries && ret)
+		mm_iommu_adjust_locked_vm(mm, locked_entries, false);
+
+	mutex_unlock(&mem_list_mutex);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(mm_iommu_get);
+
+static void mm_iommu_unpin(struct mm_iommu_table_group_mem_t *mem)
+{
+	long i;
+	struct page *page = NULL;
+
+	for (i = 0; i < mem->entries; ++i) {
+		if (!mem->hpas[i])
+			continue;
+
+		page = pfn_to_page(mem->hpas[i] >> PAGE_SHIFT);
+		if (!page)
+			continue;
+
+		if (mem->hpas[i] & MM_IOMMU_TABLE_GROUP_PAGE_DIRTY)
+			SetPageDirty(page);
+
+		put_page(page);
+		mem->hpas[i] = 0;
+	}
+}
+
+static void mm_iommu_do_free(struct mm_iommu_table_group_mem_t *mem)
+{
+
+	mm_iommu_unpin(mem);
+	vfree(mem->hpas);
+	kfree(mem);
+}
+
+static void mm_iommu_free(struct rcu_head *head)
+{
+	struct mm_iommu_table_group_mem_t *mem = container_of(head,
+			struct mm_iommu_table_group_mem_t, rcu);
+
+	mm_iommu_do_free(mem);
+}
+
+static void mm_iommu_release(struct mm_iommu_table_group_mem_t *mem)
+{
+	list_del_rcu(&mem->next);
+	call_rcu(&mem->rcu, mm_iommu_free);
+}
+
+long mm_iommu_put(struct mm_struct *mm, struct mm_iommu_table_group_mem_t *mem)
+{
+	long ret = 0;
+
+	mutex_lock(&mem_list_mutex);
+
+	if (mem->used == 0) {
+		ret = -ENOENT;
+		goto unlock_exit;
+	}
+
+	--mem->used;
+	/* There are still users, exit */
+	if (mem->used)
+		goto unlock_exit;
+
+	/* Are there still mappings? */
+	if (atomic_cmpxchg(&mem->mapped, 1, 0) != 1) {
+		++mem->used;
+		ret = -EBUSY;
+		goto unlock_exit;
+	}
+
+	/* @mapped became 0 so now mappings are disabled, release the region */
+	mm_iommu_release(mem);
+
+	mm_iommu_adjust_locked_vm(mm, mem->entries, false);
+
+unlock_exit:
+	mutex_unlock(&mem_list_mutex);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(mm_iommu_put);
+
+struct mm_iommu_table_group_mem_t *mm_iommu_lookup(struct mm_struct *mm,
+		unsigned long ua, unsigned long size)
+{
+	struct mm_iommu_table_group_mem_t *mem, *ret = NULL;
+
+	list_for_each_entry_rcu(mem, &mm->context.iommu_group_mem_list, next) {
+		if ((mem->ua <= ua) &&
+				(ua + size <= mem->ua +
+				 (mem->entries << PAGE_SHIFT))) {
+			ret = mem;
+			break;
+		}
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(mm_iommu_lookup);
+
+struct mm_iommu_table_group_mem_t *mm_iommu_lookup_rm(struct mm_struct *mm,
+		unsigned long ua, unsigned long size)
+{
+	struct mm_iommu_table_group_mem_t *mem, *ret = NULL;
+
+	list_for_each_entry_lockless(mem, &mm->context.iommu_group_mem_list,
+			next) {
+		if ((mem->ua <= ua) &&
+				(ua + size <= mem->ua +
+				 (mem->entries << PAGE_SHIFT))) {
+			ret = mem;
+			break;
+		}
+	}
+
+	return ret;
+}
+
+struct mm_iommu_table_group_mem_t *mm_iommu_find(struct mm_struct *mm,
+		unsigned long ua, unsigned long entries)
+{
+	struct mm_iommu_table_group_mem_t *mem, *ret = NULL;
+
+	list_for_each_entry_rcu(mem, &mm->context.iommu_group_mem_list, next) {
+		if ((mem->ua == ua) && (mem->entries == entries)) {
+			ret = mem;
+			break;
+		}
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(mm_iommu_find);
+
+long mm_iommu_ua_to_hpa(struct mm_iommu_table_group_mem_t *mem,
+		unsigned long ua, unsigned int pageshift, unsigned long *hpa)
+{
+	const long entry = (ua - mem->ua) >> PAGE_SHIFT;
+	u64 *va = &mem->hpas[entry];
+
+	if (entry >= mem->entries)
+		return -EFAULT;
+
+	if (pageshift > mem->pageshift)
+		return -EFAULT;
+
+	*hpa = (*va & MM_IOMMU_TABLE_GROUP_PAGE_MASK) | (ua & ~PAGE_MASK);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(mm_iommu_ua_to_hpa);
+
+long mm_iommu_ua_to_hpa_rm(struct mm_iommu_table_group_mem_t *mem,
+		unsigned long ua, unsigned int pageshift, unsigned long *hpa)
+{
+	const long entry = (ua - mem->ua) >> PAGE_SHIFT;
+	void *va = &mem->hpas[entry];
+	unsigned long *pa;
+
+	if (entry >= mem->entries)
+		return -EFAULT;
+
+	if (pageshift > mem->pageshift)
+		return -EFAULT;
+
+	pa = (void *) vmalloc_to_phys(va);
+	if (!pa)
+		return -EFAULT;
+
+	*hpa = (*pa & MM_IOMMU_TABLE_GROUP_PAGE_MASK) | (ua & ~PAGE_MASK);
+
+	return 0;
+}
+
+extern void mm_iommu_ua_mark_dirty_rm(struct mm_struct *mm, unsigned long ua)
+{
+	struct mm_iommu_table_group_mem_t *mem;
+	long entry;
+	void *va;
+	unsigned long *pa;
+
+	mem = mm_iommu_lookup_rm(mm, ua, PAGE_SIZE);
+	if (!mem)
+		return;
+
+	entry = (ua - mem->ua) >> PAGE_SHIFT;
+	va = &mem->hpas[entry];
+
+	pa = (void *) vmalloc_to_phys(va);
+	if (!pa)
+		return;
+
+	*pa |= MM_IOMMU_TABLE_GROUP_PAGE_DIRTY;
+}
+
+long mm_iommu_mapped_inc(struct mm_iommu_table_group_mem_t *mem)
+{
+	if (atomic64_inc_not_zero(&mem->mapped))
+		return 0;
+
+	/* Last mm_iommu_put() has been called, no more mappings allowed() */
+	return -ENXIO;
+}
+EXPORT_SYMBOL_GPL(mm_iommu_mapped_inc);
+
+void mm_iommu_mapped_dec(struct mm_iommu_table_group_mem_t *mem)
+{
+	atomic64_add_unless(&mem->mapped, -1, 1);
+}
+EXPORT_SYMBOL_GPL(mm_iommu_mapped_dec);
+
+void mm_iommu_init(struct mm_struct *mm)
+{
+	INIT_LIST_HEAD_RCU(&mm->context.iommu_group_mem_list);
+}