linux/drivers/iommu/io-pgtable-arm-v7s.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * CPU-agnostic ARM page table allocator.
 *
 * ARMv7 Short-descriptor format, supporting
 * - Basic memory attributes
 * - Simplified access permissions (AP[2:1] model)
 * - Backwards-compatible TEX remap
 * - Large pages/supersections (if indicated by the caller)
 *
 * Not supporting:
 * - Legacy access permissions (AP[2:0] model)
 *
 * Almost certainly never supporting:
 * - PXN
 * - Domains
 *
 * Copyright (C) 2014-2015 ARM Limited
 * Copyright (c) 2014-2015 MediaTek Inc.
 */

#define pr_fmt(fmt)	"arm-v7s io-pgtable: " fmt

#include <linux/atomic.h>
#include <linux/dma-mapping.h>
#include <linux/gfp.h>
#include <linux/io-pgtable.h>
#include <linux/iommu.h>
#include <linux/kernel.h>
#include <linux/kmemleak.h>
#include <linux/sizes.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/types.h>

#include <asm/barrier.h>

/* Struct accessors */
#define io_pgtable_to_data(x)						\
	container_of((x), struct arm_v7s_io_pgtable, iop)

#define io_pgtable_ops_to_data(x)					\
	io_pgtable_to_data(io_pgtable_ops_to_pgtable(x))

/*
 * We have 32 bits total; 12 bits resolved at level 1, 8 bits at level 2,
 * and 12 bits in a page.
 * MediaTek extend 2 bits to reach 34bits, 14 bits at lvl1 and 8 bits at lvl2.
 */
#define ARM_V7S_ADDR_BITS		32
#define _ARM_V7S_LVL_BITS(lvl, cfg)	((lvl) == 1 ? ((cfg)->ias - 20) : 8)
#define ARM_V7S_LVL_SHIFT(lvl)		((lvl) == 1 ? 20 : 12)
#define ARM_V7S_TABLE_SHIFT		10

#define ARM_V7S_PTES_PER_LVL(lvl, cfg)	(1 << _ARM_V7S_LVL_BITS(lvl, cfg))
#define ARM_V7S_TABLE_SIZE(lvl, cfg)						\
	(ARM_V7S_PTES_PER_LVL(lvl, cfg) * sizeof(arm_v7s_iopte))

#define ARM_V7S_BLOCK_SIZE(lvl)		(1UL << ARM_V7S_LVL_SHIFT(lvl))
#define ARM_V7S_LVL_MASK(lvl)		((u32)(~0U << ARM_V7S_LVL_SHIFT(lvl)))
#define ARM_V7S_TABLE_MASK		((u32)(~0U << ARM_V7S_TABLE_SHIFT))
#define _ARM_V7S_IDX_MASK(lvl, cfg)	(ARM_V7S_PTES_PER_LVL(lvl, cfg) - 1)
#define ARM_V7S_LVL_IDX(addr, lvl, cfg)	({				\
	int _l = lvl;							\
	((addr) >> ARM_V7S_LVL_SHIFT(_l)) & _ARM_V7S_IDX_MASK(_l, cfg); \
})

/*
 * Large page/supersection entries are effectively a block of 16 page/section
 * entries, along the lines of the LPAE contiguous hint, but all with the
 * same output address. For want of a better common name we'll call them
 * "contiguous" versions of their respective page/section entries here, but
 * noting the distinction (WRT to TLB maintenance) that they represent *one*
 * entry repeated 16 times, not 16 separate entries (as in the LPAE case).
 */
#define ARM_V7S_CONT_PAGES		16

/* PTE type bits: these are all mixed up with XN/PXN bits in most cases */
#define ARM_V7S_PTE_TYPE_TABLE		0x1
#define ARM_V7S_PTE_TYPE_PAGE		0x2
#define ARM_V7S_PTE_TYPE_CONT_PAGE	0x1

#define ARM_V7S_PTE_IS_VALID(pte)	(((pte) & 0x3) != 0)
#define ARM_V7S_PTE_IS_TABLE(pte, lvl) \
	((lvl) == 1 && (((pte) & 0x3) == ARM_V7S_PTE_TYPE_TABLE))

/* Page table bits */
#define ARM_V7S_ATTR_XN(lvl)		BIT(4 * (2 - (lvl)))
#define ARM_V7S_ATTR_B			BIT(2)
#define ARM_V7S_ATTR_C			BIT(3)
#define ARM_V7S_ATTR_NS_TABLE		BIT(3)
#define ARM_V7S_ATTR_NS_SECTION		BIT(19)

#define ARM_V7S_CONT_SECTION		BIT(18)
#define ARM_V7S_CONT_PAGE_XN_SHIFT	15

/*
 * The attribute bits are consistently ordered*, but occupy bits [17:10] of
 * a level 1 PTE vs. bits [11:4] at level 2. Thus we define the individual
 * fields relative to that 8-bit block, plus a total shift relative to the PTE.
 */
#define ARM_V7S_ATTR_SHIFT(lvl)		(16 - (lvl) * 6)

#define ARM_V7S_ATTR_MASK		0xff
#define ARM_V7S_ATTR_AP0		BIT(0)
#define ARM_V7S_ATTR_AP1		BIT(1)
#define ARM_V7S_ATTR_AP2		BIT(5)
#define ARM_V7S_ATTR_S			BIT(6)
#define ARM_V7S_ATTR_NG			BIT(7)
#define ARM_V7S_TEX_SHIFT		2
#define ARM_V7S_TEX_MASK		0x7
#define ARM_V7S_ATTR_TEX(val)		(((val) & ARM_V7S_TEX_MASK) << ARM_V7S_TEX_SHIFT)

/* MediaTek extend the bits below for PA 32bit/33bit/34bit */
#define ARM_V7S_ATTR_MTK_PA_BIT32	BIT(9)
#define ARM_V7S_ATTR_MTK_PA_BIT33	BIT(4)
#define ARM_V7S_ATTR_MTK_PA_BIT34	BIT(5)

/* *well, except for TEX on level 2 large pages, of course :( */
#define ARM_V7S_CONT_PAGE_TEX_SHIFT	6
#define ARM_V7S_CONT_PAGE_TEX_MASK	(ARM_V7S_TEX_MASK << ARM_V7S_CONT_PAGE_TEX_SHIFT)

/* Simplified access permissions */
#define ARM_V7S_PTE_AF			ARM_V7S_ATTR_AP0
#define ARM_V7S_PTE_AP_UNPRIV		ARM_V7S_ATTR_AP1
#define ARM_V7S_PTE_AP_RDONLY		ARM_V7S_ATTR_AP2

/* Register bits */
#define ARM_V7S_RGN_NC			0
#define ARM_V7S_RGN_WBWA		1
#define ARM_V7S_RGN_WT			2
#define ARM_V7S_RGN_WB			3

#define ARM_V7S_PRRR_TYPE_DEVICE	1
#define ARM_V7S_PRRR_TYPE_NORMAL	2
#define ARM_V7S_PRRR_TR(n, type)	(((type) & 0x3) << ((n) * 2))
#define ARM_V7S_PRRR_DS0		BIT(16)
#define ARM_V7S_PRRR_DS1		BIT(17)
#define ARM_V7S_PRRR_NS0		BIT(18)
#define ARM_V7S_PRRR_NS1		BIT(19)
#define ARM_V7S_PRRR_NOS(n)		BIT((n) + 24)

#define ARM_V7S_NMRR_IR(n, attr)	(((attr) & 0x3) << ((n) * 2))
#define ARM_V7S_NMRR_OR(n, attr)	(((attr) & 0x3) << ((n) * 2 + 16))

#define ARM_V7S_TTBR_S			BIT(1)
#define ARM_V7S_TTBR_NOS		BIT(5)
#define ARM_V7S_TTBR_ORGN_ATTR(attr)	(((attr) & 0x3) << 3)
#define ARM_V7S_TTBR_IRGN_ATTR(attr)					\
	((((attr) & 0x1) << 6) | (((attr) & 0x2) >> 1))

#ifdef CONFIG_ZONE_DMA32
#define ARM_V7S_TABLE_GFP_DMA GFP_DMA32
#define ARM_V7S_TABLE_SLAB_FLAGS SLAB_CACHE_DMA32
#else
#define ARM_V7S_TABLE_GFP_DMA GFP_DMA
#define ARM_V7S_TABLE_SLAB_FLAGS SLAB_CACHE_DMA
#endif

typedef u32 arm_v7s_iopte;

static bool selftest_running;

struct arm_v7s_io_pgtable {
	struct io_pgtable	iop;

	arm_v7s_iopte		*pgd;
	struct kmem_cache	*l2_tables;
};

static bool arm_v7s_pte_is_cont(arm_v7s_iopte pte, int lvl);

static dma_addr_t __arm_v7s_dma_addr(void *pages)
{
	return (dma_addr_t)virt_to_phys(pages);
}

static bool arm_v7s_is_mtk_enabled(struct io_pgtable_cfg *cfg)
{
	return IS_ENABLED(CONFIG_PHYS_ADDR_T_64BIT) &&
		(cfg->quirks & IO_PGTABLE_QUIRK_ARM_MTK_EXT);
}

static arm_v7s_iopte to_mtk_iopte(phys_addr_t paddr, arm_v7s_iopte pte)
{
	if (paddr & BIT_ULL(32))
		pte |= ARM_V7S_ATTR_MTK_PA_BIT32;
	if (paddr & BIT_ULL(33))
		pte |= ARM_V7S_ATTR_MTK_PA_BIT33;
	if (paddr & BIT_ULL(34))
		pte |= ARM_V7S_ATTR_MTK_PA_BIT34;
	return pte;
}

static arm_v7s_iopte paddr_to_iopte(phys_addr_t paddr, int lvl,
				    struct io_pgtable_cfg *cfg)
{
	arm_v7s_iopte pte = paddr & ARM_V7S_LVL_MASK(lvl);

	if (arm_v7s_is_mtk_enabled(cfg))
		return to_mtk_iopte(paddr, pte);

	return pte;
}

static phys_addr_t iopte_to_paddr(arm_v7s_iopte pte, int lvl,
				  struct io_pgtable_cfg *cfg)
{
	arm_v7s_iopte mask;
	phys_addr_t paddr;

	if (ARM_V7S_PTE_IS_TABLE(pte, lvl))
		mask = ARM_V7S_TABLE_MASK;
	else if (arm_v7s_pte_is_cont(pte, lvl))
		mask = ARM_V7S_LVL_MASK(lvl) * ARM_V7S_CONT_PAGES;
	else
		mask = ARM_V7S_LVL_MASK(lvl);

	paddr = pte & mask;
	if (!arm_v7s_is_mtk_enabled(cfg))
		return paddr;

	if (pte & ARM_V7S_ATTR_MTK_PA_BIT32)
		paddr |= BIT_ULL(32);
	if (pte & ARM_V7S_ATTR_MTK_PA_BIT33)
		paddr |= BIT_ULL(33);
	if (pte & ARM_V7S_ATTR_MTK_PA_BIT34)
		paddr |= BIT_ULL(34);
	return paddr;
}

static arm_v7s_iopte *iopte_deref(arm_v7s_iopte pte, int lvl,
				  struct arm_v7s_io_pgtable *data)
{
	return phys_to_virt(iopte_to_paddr(pte, lvl, &data->iop.cfg));
}

static void *__arm_v7s_alloc_table(int lvl, gfp_t gfp,
				   struct arm_v7s_io_pgtable *data)
{
	struct io_pgtable_cfg *cfg = &data->iop.cfg;
	struct device *dev = cfg->iommu_dev;
	phys_addr_t phys;
	dma_addr_t dma;
	size_t size = ARM_V7S_TABLE_SIZE(lvl, cfg);
	void *table = NULL;
	gfp_t gfp_l1;

	/*
	 * ARM_MTK_TTBR_EXT extend the translation table base support larger
	 * memory address.
	 */
	gfp_l1 = cfg->quirks & IO_PGTABLE_QUIRK_ARM_MTK_TTBR_EXT ?
		 GFP_KERNEL : ARM_V7S_TABLE_GFP_DMA;

	if (lvl == 1)
		table = (void *)__get_free_pages(gfp_l1 | __GFP_ZERO, get_order(size));
	else if (lvl == 2)
		table = kmem_cache_zalloc(data->l2_tables, gfp);

	if (!table)
		return NULL;

	phys = virt_to_phys(table);
	if (cfg->quirks & IO_PGTABLE_QUIRK_ARM_MTK_TTBR_EXT ?
	    phys >= (1ULL << cfg->oas) : phys != (arm_v7s_iopte)phys) {
		/* Doesn't fit in PTE */
		dev_err(dev, "Page table does not fit in PTE: %pa", &phys);
		goto out_free;
	}
	if (!cfg->coherent_walk) {
		dma = dma_map_single(dev, table, size, DMA_TO_DEVICE);
		if (dma_mapping_error(dev, dma))
			goto out_free;
		/*
		 * We depend on the IOMMU being able to work with any physical
		 * address directly, so if the DMA layer suggests otherwise by
		 * translating or truncating them, that bodes very badly...
		 */
		if (dma != phys)
			goto out_unmap;
	}
	if (lvl == 2)
		kmemleak_ignore(table);
	return table;

out_unmap:
	dev_err(dev, "Cannot accommodate DMA translation for IOMMU page tables\n");
	dma_unmap_single(dev, dma, size, DMA_TO_DEVICE);
out_free:
	if (lvl == 1)
		free_pages((unsigned long)table, get_order(size));
	else
		kmem_cache_free(data->l2_tables, table);
	return NULL;
}

static void __arm_v7s_free_table(void *table, int lvl,
				 struct arm_v7s_io_pgtable *data)
{
	struct io_pgtable_cfg *cfg = &data->iop.cfg;
	struct device *dev = cfg->iommu_dev;
	size_t size = ARM_V7S_TABLE_SIZE(lvl, cfg);

	if (!cfg->coherent_walk)
		dma_unmap_single(dev, __arm_v7s_dma_addr(table), size,
				 DMA_TO_DEVICE);
	if (lvl == 1)
		free_pages((unsigned long)table, get_order(size));
	else
		kmem_cache_free(data->l2_tables, table);
}

static void __arm_v7s_pte_sync(arm_v7s_iopte *ptep, int num_entries,
			       struct io_pgtable_cfg *cfg)
{
	if (cfg->coherent_walk)
		return;

	dma_sync_single_for_device(cfg->iommu_dev, __arm_v7s_dma_addr(ptep),
				   num_entries * sizeof(*ptep), DMA_TO_DEVICE);
}
static void __arm_v7s_set_pte(arm_v7s_iopte *ptep, arm_v7s_iopte pte,
			      int num_entries, struct io_pgtable_cfg *cfg)
{
	int i;

	for (i = 0; i < num_entries; i++)
		ptep[i] = pte;

	__arm_v7s_pte_sync(ptep, num_entries, cfg);
}

static arm_v7s_iopte arm_v7s_prot_to_pte(int prot, int lvl,
					 struct io_pgtable_cfg *cfg)
{
	bool ap = !(cfg->quirks & IO_PGTABLE_QUIRK_NO_PERMS);
	arm_v7s_iopte pte = ARM_V7S_ATTR_NG | ARM_V7S_ATTR_S;

	if (!(prot & IOMMU_MMIO))
		pte |= ARM_V7S_ATTR_TEX(1);
	if (ap) {
		pte |= ARM_V7S_PTE_AF;
		if (!(prot & IOMMU_PRIV))
			pte |= ARM_V7S_PTE_AP_UNPRIV;
		if (!(prot & IOMMU_WRITE))
			pte |= ARM_V7S_PTE_AP_RDONLY;
	}
	pte <<= ARM_V7S_ATTR_SHIFT(lvl);

	if ((prot & IOMMU_NOEXEC) && ap)
		pte |= ARM_V7S_ATTR_XN(lvl);
	if (prot & IOMMU_MMIO)
		pte |= ARM_V7S_ATTR_B;
	else if (prot & IOMMU_CACHE)
		pte |= ARM_V7S_ATTR_B | ARM_V7S_ATTR_C;

	pte |= ARM_V7S_PTE_TYPE_PAGE;
	if (lvl == 1 && (cfg->quirks & IO_PGTABLE_QUIRK_ARM_NS))
		pte |= ARM_V7S_ATTR_NS_SECTION;

	return pte;
}

static arm_v7s_iopte arm_v7s_pte_to_cont(arm_v7s_iopte pte, int lvl)
{
	if (lvl == 1) {
		pte |= ARM_V7S_CONT_SECTION;
	} else if (lvl == 2) {
		arm_v7s_iopte xn = pte & ARM_V7S_ATTR_XN(lvl);
		arm_v7s_iopte tex = pte & ARM_V7S_CONT_PAGE_TEX_MASK;

		pte ^= xn | tex | ARM_V7S_PTE_TYPE_PAGE;
		pte |= (xn << ARM_V7S_CONT_PAGE_XN_SHIFT) |
		       (tex << ARM_V7S_CONT_PAGE_TEX_SHIFT) |
		       ARM_V7S_PTE_TYPE_CONT_PAGE;
	}
	return pte;
}

static bool arm_v7s_pte_is_cont(arm_v7s_iopte pte, int lvl)
{
	if (lvl == 1 && !ARM_V7S_PTE_IS_TABLE(pte, lvl))
		return pte & ARM_V7S_CONT_SECTION;
	else if (lvl == 2)
		return !(pte & ARM_V7S_PTE_TYPE_PAGE);
	return false;
}

static size_t __arm_v7s_unmap(struct arm_v7s_io_pgtable *,
			      struct iommu_iotlb_gather *, unsigned long,
			      size_t, int, arm_v7s_iopte *);

static int arm_v7s_init_pte(struct arm_v7s_io_pgtable *data,
			    unsigned long iova, phys_addr_t paddr, int prot,
			    int lvl, int num_entries, arm_v7s_iopte *ptep)
{
	struct io_pgtable_cfg *cfg = &data->iop.cfg;
	arm_v7s_iopte pte;
	int i;

	for (i = 0; i < num_entries; i++)
		if (ARM_V7S_PTE_IS_TABLE(ptep[i], lvl)) {
			/*
			 * We need to unmap and free the old table before
			 * overwriting it with a block entry.
			 */
			arm_v7s_iopte *tblp;
			size_t sz = ARM_V7S_BLOCK_SIZE(lvl);

			tblp = ptep - ARM_V7S_LVL_IDX(iova, lvl, cfg);
			if (WARN_ON(__arm_v7s_unmap(data, NULL, iova + i * sz,
						    sz, lvl, tblp) != sz))
				return -EINVAL;
		} else if (ptep[i]) {
			/* We require an unmap first */
			WARN_ON(!selftest_running);
			return -EEXIST;
		}

	pte = arm_v7s_prot_to_pte(prot, lvl, cfg);
	if (num_entries > 1)
		pte = arm_v7s_pte_to_cont(pte, lvl);

	pte |= paddr_to_iopte(paddr, lvl, cfg);

	__arm_v7s_set_pte(ptep, pte, num_entries, cfg);
	return 0;
}

static arm_v7s_iopte arm_v7s_install_table(arm_v7s_iopte *table,
					   arm_v7s_iopte *ptep,
					   arm_v7s_iopte curr,
					   struct io_pgtable_cfg *cfg)
{
	phys_addr_t phys = virt_to_phys(table);
	arm_v7s_iopte old, new;

	new = phys | ARM_V7S_PTE_TYPE_TABLE;

	if (cfg->quirks & IO_PGTABLE_QUIRK_ARM_MTK_TTBR_EXT)
		new = to_mtk_iopte(phys, new);

	if (cfg->quirks & IO_PGTABLE_QUIRK_ARM_NS)
		new |= ARM_V7S_ATTR_NS_TABLE;

	/*
	 * Ensure the table itself is visible before its PTE can be.
	 * Whilst we could get away with cmpxchg64_release below, this
	 * doesn't have any ordering semantics when !CONFIG_SMP.
	 */
	dma_wmb();

	old = cmpxchg_relaxed(ptep, curr, new);
	__arm_v7s_pte_sync(ptep, 1, cfg);

	return old;
}

static int __arm_v7s_map(struct arm_v7s_io_pgtable *data, unsigned long iova,
			 phys_addr_t paddr, size_t size, int prot,
			 int lvl, arm_v7s_iopte *ptep, gfp_t gfp)
{
	struct io_pgtable_cfg *cfg = &data->iop.cfg;
	arm_v7s_iopte pte, *cptep;
	int num_entries = size >> ARM_V7S_LVL_SHIFT(lvl);

	/* Find our entry at the current level */
	ptep += ARM_V7S_LVL_IDX(iova, lvl, cfg);

	/* If we can install a leaf entry at this level, then do so */
	if (num_entries)
		return arm_v7s_init_pte(data, iova, paddr, prot,
					lvl, num_entries, ptep);

	/* We can't allocate tables at the final level */
	if (WARN_ON(lvl == 2))
		return -EINVAL;

	/* Grab a pointer to the next level */
	pte = READ_ONCE(*ptep);
	if (!pte) {
		cptep = __arm_v7s_alloc_table(lvl + 1, gfp, data);
		if (!cptep)
			return -ENOMEM;

		pte = arm_v7s_install_table(cptep, ptep, 0, cfg);
		if (pte)
			__arm_v7s_free_table(cptep, lvl + 1, data);
	} else {
		/* We've no easy way of knowing if it's synced yet, so... */
		__arm_v7s_pte_sync(ptep, 1, cfg);
	}

	if (ARM_V7S_PTE_IS_TABLE(pte, lvl)) {
		cptep = iopte_deref(pte, lvl, data);
	} else if (pte) {
		/* We require an unmap first */
		WARN_ON(!selftest_running);
		return -EEXIST;
	}

	/* Rinse, repeat */
	return __arm_v7s_map(data, iova, paddr, size, prot, lvl + 1, cptep, gfp);
}

static int arm_v7s_map_pages(struct io_pgtable_ops *ops, unsigned long iova,
			     phys_addr_t paddr, size_t pgsize, size_t pgcount,
			     int prot, gfp_t gfp, size_t *mapped)
{
	struct arm_v7s_io_pgtable *data = io_pgtable_ops_to_data(ops);
	int ret = -EINVAL;

	if (WARN_ON(iova >= (1ULL << data->iop.cfg.ias) ||
		    paddr >= (1ULL << data->iop.cfg.oas)))
		return -ERANGE;

	if (!(prot & (IOMMU_READ | IOMMU_WRITE)))
		return -EINVAL;

	while (pgcount--) {
		ret = __arm_v7s_map(data, iova, paddr, pgsize, prot, 1, data->pgd,
				    gfp);
		if (ret)
			break;

		iova += pgsize;
		paddr += pgsize;
		*mapped += pgsize;
	}
	/*
	 * Synchronise all PTE updates for the new mapping before there's
	 * a chance for anything to kick off a table walk for the new iova.
	 */
	wmb();

	return ret;
}

static void arm_v7s_free_pgtable(struct io_pgtable *iop)
{
	struct arm_v7s_io_pgtable *data = io_pgtable_to_data(iop);
	int i;

	for (i = 0; i < ARM_V7S_PTES_PER_LVL(1, &data->iop.cfg); i++) {
		arm_v7s_iopte pte = data->pgd[i];

		if (ARM_V7S_PTE_IS_TABLE(pte, 1))
			__arm_v7s_free_table(iopte_deref(pte, 1, data),
					     2, data);
	}
	__arm_v7s_free_table(data->pgd, 1, data);
	kmem_cache_destroy(data->l2_tables);
	kfree(data);
}

static size_t __arm_v7s_unmap(struct arm_v7s_io_pgtable *data,
			      struct iommu_iotlb_gather *gather,
			      unsigned long iova, size_t size, int lvl,
			      arm_v7s_iopte *ptep)
{
	arm_v7s_iopte pte[ARM_V7S_CONT_PAGES];
	struct io_pgtable *iop = &data->iop;
	int idx, i = 0, num_entries = size >> ARM_V7S_LVL_SHIFT(lvl);

	/* Something went horribly wrong and we ran out of page table */
	if (WARN_ON(lvl > 2))
		return 0;

	idx = ARM_V7S_LVL_IDX(iova, lvl, &iop->cfg);
	ptep += idx;
	do {
		pte[i] = READ_ONCE(ptep[i]);
		if (WARN_ON(!ARM_V7S_PTE_IS_VALID(pte[i])))
			return 0;
	} while (++i < num_entries);

	/*
	 * If we've hit a contiguous 'large page' entry at this level, it
	 * needs splitting first, unless we're unmapping the whole lot.
	 *
	 * For splitting, we can't rewrite 16 PTEs atomically, and since we
	 * can't necessarily assume TEX remap we don't have a software bit to
	 * mark live entries being split. In practice (i.e. DMA API code), we
	 * will never be splitting large pages anyway, so just wrap this edge
	 * case in a lock for the sake of correctness and be done with it.
	 */
	if (num_entries <= 1 && arm_v7s_pte_is_cont(pte[0], lvl)) {
		WARN_ONCE(true, "Unmap of a partial large IOPTE is not allowed");
		return 0;
	}

	/* If the size matches this level, we're in the right place */
	if (num_entries) {
		size_t blk_size = ARM_V7S_BLOCK_SIZE(lvl);

		__arm_v7s_set_pte(ptep, 0, num_entries, &iop->cfg);

		for (i = 0; i < num_entries; i++) {
			if (ARM_V7S_PTE_IS_TABLE(pte[i], lvl)) {
				/* Also flush any partial walks */
				io_pgtable_tlb_flush_walk(iop, iova, blk_size,
						ARM_V7S_BLOCK_SIZE(lvl + 1));
				ptep = iopte_deref(pte[i], lvl, data);
				__arm_v7s_free_table(ptep, lvl + 1, data);
			} else if (!iommu_iotlb_gather_queued(gather)) {
				io_pgtable_tlb_add_page(iop, gather, iova, blk_size);
			}
			iova += blk_size;
		}
		return size;
	} else if (lvl == 1 && !ARM_V7S_PTE_IS_TABLE(pte[0], lvl)) {
		WARN_ONCE(true, "Unmap of a partial large IOPTE is not allowed");
		return 0;
	}

	/* Keep on walkin' */
	ptep = iopte_deref(pte[0], lvl, data);
	return __arm_v7s_unmap(data, gather, iova, size, lvl + 1, ptep);
}

static size_t arm_v7s_unmap_pages(struct io_pgtable_ops *ops, unsigned long iova,
				  size_t pgsize, size_t pgcount,
				  struct iommu_iotlb_gather *gather)
{
	struct arm_v7s_io_pgtable *data = io_pgtable_ops_to_data(ops);
	size_t unmapped = 0, ret;

	if (WARN_ON(iova >= (1ULL << data->iop.cfg.ias)))
		return 0;

	while (pgcount--) {
		ret = __arm_v7s_unmap(data, gather, iova, pgsize, 1, data->pgd);
		if (!ret)
			break;

		unmapped += pgsize;
		iova += pgsize;
	}

	return unmapped;
}

static phys_addr_t arm_v7s_iova_to_phys(struct io_pgtable_ops *ops,
					unsigned long iova)
{
	struct arm_v7s_io_pgtable *data = io_pgtable_ops_to_data(ops);
	arm_v7s_iopte *ptep = data->pgd, pte;
	int lvl = 0;
	u32 mask;

	do {
		ptep += ARM_V7S_LVL_IDX(iova, ++lvl, &data->iop.cfg);
		pte = READ_ONCE(*ptep);
		ptep = iopte_deref(pte, lvl, data);
	} while (ARM_V7S_PTE_IS_TABLE(pte, lvl));

	if (!ARM_V7S_PTE_IS_VALID(pte))
		return 0;

	mask = ARM_V7S_LVL_MASK(lvl);
	if (arm_v7s_pte_is_cont(pte, lvl))
		mask *= ARM_V7S_CONT_PAGES;
	return iopte_to_paddr(pte, lvl, &data->iop.cfg) | (iova & ~mask);
}

static struct io_pgtable *arm_v7s_alloc_pgtable(struct io_pgtable_cfg *cfg,
						void *cookie)
{
	struct arm_v7s_io_pgtable *data;
	slab_flags_t slab_flag;
	phys_addr_t paddr;

	if (cfg->ias > (arm_v7s_is_mtk_enabled(cfg) ? 34 : ARM_V7S_ADDR_BITS))
		return NULL;

	if (cfg->oas > (arm_v7s_is_mtk_enabled(cfg) ? 35 : ARM_V7S_ADDR_BITS))
		return NULL;

	if (cfg->quirks & ~(IO_PGTABLE_QUIRK_ARM_NS |
			    IO_PGTABLE_QUIRK_NO_PERMS |
			    IO_PGTABLE_QUIRK_ARM_MTK_EXT |
			    IO_PGTABLE_QUIRK_ARM_MTK_TTBR_EXT))
		return NULL;

	/* If ARM_MTK_4GB is enabled, the NO_PERMS is also expected. */
	if (cfg->quirks & IO_PGTABLE_QUIRK_ARM_MTK_EXT &&
	    !(cfg->quirks & IO_PGTABLE_QUIRK_NO_PERMS))
			return NULL;

	if ((cfg->quirks & IO_PGTABLE_QUIRK_ARM_MTK_TTBR_EXT) &&
	    !arm_v7s_is_mtk_enabled(cfg))
		return NULL;

	data = kmalloc(sizeof(*data), GFP_KERNEL);
	if (!data)
		return NULL;

	/*
	 * ARM_MTK_TTBR_EXT extend the translation table base support larger
	 * memory address.
	 */
	slab_flag = cfg->quirks & IO_PGTABLE_QUIRK_ARM_MTK_TTBR_EXT ?
		    0 : ARM_V7S_TABLE_SLAB_FLAGS;

	data->l2_tables = kmem_cache_create("io-pgtable_armv7s_l2",
					    ARM_V7S_TABLE_SIZE(2, cfg),
					    ARM_V7S_TABLE_SIZE(2, cfg),
					    slab_flag, NULL);
	if (!data->l2_tables)
		goto out_free_data;

	data->iop.ops = (struct io_pgtable_ops) {
		.map_pages	= arm_v7s_map_pages,
		.unmap_pages	= arm_v7s_unmap_pages,
		.iova_to_phys	= arm_v7s_iova_to_phys,
	};

	/* We have to do this early for __arm_v7s_alloc_table to work... */
	data->iop.cfg = *cfg;

	/*
	 * Unless the IOMMU driver indicates supersection support by
	 * having SZ_16M set in the initial bitmap, they won't be used.
	 */
	cfg->pgsize_bitmap &= SZ_4K | SZ_64K | SZ_1M | SZ_16M;

	/* TCR: T0SZ=0, EAE=0 (if applicable) */
	cfg->arm_v7s_cfg.tcr = 0;

	/*
	 * TEX remap: the indices used map to the closest equivalent types
	 * under the non-TEX-remap interpretation of those attribute bits,
	 * excepting various implementation-defined aspects of shareability.
	 */
	cfg->arm_v7s_cfg.prrr = ARM_V7S_PRRR_TR(1, ARM_V7S_PRRR_TYPE_DEVICE) |
				ARM_V7S_PRRR_TR(4, ARM_V7S_PRRR_TYPE_NORMAL) |
				ARM_V7S_PRRR_TR(7, ARM_V7S_PRRR_TYPE_NORMAL) |
				ARM_V7S_PRRR_DS0 | ARM_V7S_PRRR_DS1 |
				ARM_V7S_PRRR_NS1 | ARM_V7S_PRRR_NOS(7);
	cfg->arm_v7s_cfg.nmrr = ARM_V7S_NMRR_IR(7, ARM_V7S_RGN_WBWA) |
				ARM_V7S_NMRR_OR(7, ARM_V7S_RGN_WBWA);

	/* Looking good; allocate a pgd */
	data->pgd = __arm_v7s_alloc_table(1, GFP_KERNEL, data);
	if (!data->pgd)
		goto out_free_data;

	/* Ensure the empty pgd is visible before any actual TTBR write */
	wmb();

	/* TTBR */
	paddr = virt_to_phys(data->pgd);
	if (arm_v7s_is_mtk_enabled(cfg))
		cfg->arm_v7s_cfg.ttbr = paddr | upper_32_bits(paddr);
	else
		cfg->arm_v7s_cfg.ttbr = paddr | ARM_V7S_TTBR_S |
					(cfg->coherent_walk ? (ARM_V7S_TTBR_NOS |
					 ARM_V7S_TTBR_IRGN_ATTR(ARM_V7S_RGN_WBWA) |
					 ARM_V7S_TTBR_ORGN_ATTR(ARM_V7S_RGN_WBWA)) :
					(ARM_V7S_TTBR_IRGN_ATTR(ARM_V7S_RGN_NC) |
					 ARM_V7S_TTBR_ORGN_ATTR(ARM_V7S_RGN_NC)));
	return &data->iop;

out_free_data:
	kmem_cache_destroy(data->l2_tables);
	kfree(data);
	return NULL;
}

struct io_pgtable_init_fns io_pgtable_arm_v7s_init_fns = {
	.alloc	= arm_v7s_alloc_pgtable,
	.free	= arm_v7s_free_pgtable,
};

#ifdef CONFIG_IOMMU_IO_PGTABLE_ARMV7S_SELFTEST

static struct io_pgtable_cfg *cfg_cookie __initdata;

static void __init dummy_tlb_flush_all(void *cookie)
{
	WARN_ON(cookie != cfg_cookie);
}

static void __init dummy_tlb_flush(unsigned long iova, size_t size,
				   size_t granule, void *cookie)
{
	WARN_ON(cookie != cfg_cookie);
	WARN_ON(!(size & cfg_cookie->pgsize_bitmap));
}

static void __init dummy_tlb_add_page(struct iommu_iotlb_gather *gather,
				      unsigned long iova, size_t granule,
				      void *cookie)
{
	dummy_tlb_flush(iova, granule, granule, cookie);
}

static const struct iommu_flush_ops dummy_tlb_ops __initconst = {
	.tlb_flush_all	= dummy_tlb_flush_all,
	.tlb_flush_walk	= dummy_tlb_flush,
	.tlb_add_page	= dummy_tlb_add_page,
};

#define __FAIL(ops)	({				\
		WARN(1, "selftest: test failed\n");	\
		selftest_running = false;		\
		-EFAULT;				\
})

static int __init arm_v7s_do_selftests(void)
{
	struct io_pgtable_ops *ops;
	struct io_pgtable_cfg cfg = {
		.tlb = &dummy_tlb_ops,
		.oas = 32,
		.ias = 32,
		.coherent_walk = true,
		.quirks = IO_PGTABLE_QUIRK_ARM_NS,
		.pgsize_bitmap = SZ_4K | SZ_64K | SZ_1M | SZ_16M,
	};
	unsigned int iova, size;
	unsigned int i;
	size_t mapped;

	selftest_running = true;

	cfg_cookie = &cfg;

	ops = alloc_io_pgtable_ops(ARM_V7S, &cfg, &cfg);
	if (!ops) {
		pr_err("selftest: failed to allocate io pgtable ops\n");
		return -EINVAL;
	}

	/*
	 * Initial sanity checks.
	 * Empty page tables shouldn't provide any translations.
	 */
	if (ops->iova_to_phys(ops, 42))
		return __FAIL(ops);

	if (ops->iova_to_phys(ops, SZ_1G + 42))
		return __FAIL(ops);

	if (ops->iova_to_phys(ops, SZ_2G + 42))
		return __FAIL(ops);

	/*
	 * Distinct mappings of different granule sizes.
	 */
	iova = 0;
	for_each_set_bit(i, &cfg.pgsize_bitmap, BITS_PER_LONG) {
		size = 1UL << i;
		if (ops->map_pages(ops, iova, iova, size, 1,
				   IOMMU_READ | IOMMU_WRITE |
				   IOMMU_NOEXEC | IOMMU_CACHE,
				   GFP_KERNEL, &mapped))
			return __FAIL(ops);

		/* Overlapping mappings */
		if (!ops->map_pages(ops, iova, iova + size, size, 1,
				    IOMMU_READ | IOMMU_NOEXEC, GFP_KERNEL,
				    &mapped))
			return __FAIL(ops);

		if (ops->iova_to_phys(ops, iova + 42) != (iova + 42))
			return __FAIL(ops);

		iova += SZ_16M;
	}

	/* Full unmap */
	iova = 0;
	for_each_set_bit(i, &cfg.pgsize_bitmap, BITS_PER_LONG) {
		size = 1UL << i;

		if (ops->unmap_pages(ops, iova, size, 1, NULL) != size)
			return __FAIL(ops);

		if (ops->iova_to_phys(ops, iova + 42))
			return __FAIL(ops);

		/* Remap full block */
		if (ops->map_pages(ops, iova, iova, size, 1, IOMMU_WRITE,
				   GFP_KERNEL, &mapped))
			return __FAIL(ops);

		if (ops->iova_to_phys(ops, iova + 42) != (iova + 42))
			return __FAIL(ops);

		iova += SZ_16M;
	}

	free_io_pgtable_ops(ops);

	selftest_running = false;

	pr_info("self test ok\n");
	return 0;
}
subsys_initcall(arm_v7s_do_selftests);
#endif