iommu: add ARM LPAE page table allocator

A number of IOMMUs found in ARM SoCs can walk architecture-compatible
page tables.

This patch adds a generic allocator for Stage-1 and Stage-2 v7/v8
long-descriptor page tables. 4k, 16k and 64k pages are supported, with
up to 4-levels of walk to cover a 48-bit address space.

Tested-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

1 files changed, 781 insertions, 0 deletions

diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c
new file mode 100644
index 000000000000..dbe6178a53e9
--- /dev/null
+++ b/drivers/iommu/io-pgtable-arm.c
@@ -0,0 +1,781 @@
+/*
+ * CPU-agnostic ARM page table allocator.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Copyright (C) 2014 ARM Limited
+ *
+ * Author: Will Deacon <will.deacon@arm.com>
+ */
+
+#define pr_fmt(fmt)	"arm-lpae io-pgtable: " fmt
+
+#include <linux/iommu.h>
+#include <linux/kernel.h>
+#include <linux/sizes.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+
+#include "io-pgtable.h"
+
+#define ARM_LPAE_MAX_ADDR_BITS		48
+#define ARM_LPAE_S2_MAX_CONCAT_PAGES	16
+#define ARM_LPAE_MAX_LEVELS		4
+
+/* Struct accessors */
+#define io_pgtable_to_data(x)						\
+	container_of((x), struct arm_lpae_io_pgtable, iop)
+
+#define io_pgtable_ops_to_pgtable(x)					\
+	container_of((x), struct io_pgtable, ops)
+
+#define io_pgtable_ops_to_data(x)					\
+	io_pgtable_to_data(io_pgtable_ops_to_pgtable(x))
+
+/*
+ * For consistency with the architecture, we always consider
+ * ARM_LPAE_MAX_LEVELS levels, with the walk starting at level n >=0
+ */
+#define ARM_LPAE_START_LVL(d)		(ARM_LPAE_MAX_LEVELS - (d)->levels)
+
+/*
+ * Calculate the right shift amount to get to the portion describing level l
+ * in a virtual address mapped by the pagetable in d.
+ */
+#define ARM_LPAE_LVL_SHIFT(l,d)						\
+	((((d)->levels - ((l) - ARM_LPAE_START_LVL(d) + 1))		\
+	  * (d)->bits_per_level) + (d)->pg_shift)
+
+#define ARM_LPAE_PAGES_PER_PGD(d)	((d)->pgd_size >> (d)->pg_shift)
+
+/*
+ * Calculate the index at level l used to map virtual address a using the
+ * pagetable in d.
+ */
+#define ARM_LPAE_PGD_IDX(l,d)						\
+	((l) == ARM_LPAE_START_LVL(d) ? ilog2(ARM_LPAE_PAGES_PER_PGD(d)) : 0)
+
+#define ARM_LPAE_LVL_IDX(a,l,d)						\
+	(((a) >> ARM_LPAE_LVL_SHIFT(l,d)) &				\
+	 ((1 << ((d)->bits_per_level + ARM_LPAE_PGD_IDX(l,d))) - 1))
+
+/* Calculate the block/page mapping size at level l for pagetable in d. */
+#define ARM_LPAE_BLOCK_SIZE(l,d)					\
+	(1 << (ilog2(sizeof(arm_lpae_iopte)) +				\
+		((ARM_LPAE_MAX_LEVELS - (l)) * (d)->bits_per_level)))
+
+/* Page table bits */
+#define ARM_LPAE_PTE_TYPE_SHIFT		0
+#define ARM_LPAE_PTE_TYPE_MASK		0x3
+
+#define ARM_LPAE_PTE_TYPE_BLOCK		1
+#define ARM_LPAE_PTE_TYPE_TABLE		3
+#define ARM_LPAE_PTE_TYPE_PAGE		3
+
+#define ARM_LPAE_PTE_XN			(((arm_lpae_iopte)3) << 53)
+#define ARM_LPAE_PTE_AF			(((arm_lpae_iopte)1) << 10)
+#define ARM_LPAE_PTE_SH_NS		(((arm_lpae_iopte)0) << 8)
+#define ARM_LPAE_PTE_SH_OS		(((arm_lpae_iopte)2) << 8)
+#define ARM_LPAE_PTE_SH_IS		(((arm_lpae_iopte)3) << 8)
+#define ARM_LPAE_PTE_VALID		(((arm_lpae_iopte)1) << 0)
+
+#define ARM_LPAE_PTE_ATTR_LO_MASK	(((arm_lpae_iopte)0x3ff) << 2)
+/* Ignore the contiguous bit for block splitting */
+#define ARM_LPAE_PTE_ATTR_HI_MASK	(((arm_lpae_iopte)6) << 52)
+#define ARM_LPAE_PTE_ATTR_MASK		(ARM_LPAE_PTE_ATTR_LO_MASK |	\
+					 ARM_LPAE_PTE_ATTR_HI_MASK)
+
+/* Stage-1 PTE */
+#define ARM_LPAE_PTE_AP_UNPRIV		(((arm_lpae_iopte)1) << 6)
+#define ARM_LPAE_PTE_AP_RDONLY		(((arm_lpae_iopte)2) << 6)
+#define ARM_LPAE_PTE_ATTRINDX_SHIFT	2
+#define ARM_LPAE_PTE_nG			(((arm_lpae_iopte)1) << 11)
+
+/* Stage-2 PTE */
+#define ARM_LPAE_PTE_HAP_FAULT		(((arm_lpae_iopte)0) << 6)
+#define ARM_LPAE_PTE_HAP_READ		(((arm_lpae_iopte)1) << 6)
+#define ARM_LPAE_PTE_HAP_WRITE		(((arm_lpae_iopte)2) << 6)
+#define ARM_LPAE_PTE_MEMATTR_OIWB	(((arm_lpae_iopte)0xf) << 2)
+#define ARM_LPAE_PTE_MEMATTR_NC		(((arm_lpae_iopte)0x5) << 2)
+#define ARM_LPAE_PTE_MEMATTR_DEV	(((arm_lpae_iopte)0x1) << 2)
+
+/* Register bits */
+#define ARM_32_LPAE_TCR_EAE		(1 << 31)
+#define ARM_64_LPAE_S2_TCR_RES1		(1 << 31)
+
+#define ARM_LPAE_TCR_TG0_4K		(0 << 14)
+#define ARM_LPAE_TCR_TG0_64K		(1 << 14)
+#define ARM_LPAE_TCR_TG0_16K		(2 << 14)
+
+#define ARM_LPAE_TCR_SH0_SHIFT		12
+#define ARM_LPAE_TCR_SH0_MASK		0x3
+#define ARM_LPAE_TCR_SH_NS		0
+#define ARM_LPAE_TCR_SH_OS		2
+#define ARM_LPAE_TCR_SH_IS		3
+
+#define ARM_LPAE_TCR_ORGN0_SHIFT	10
+#define ARM_LPAE_TCR_IRGN0_SHIFT	8
+#define ARM_LPAE_TCR_RGN_MASK		0x3
+#define ARM_LPAE_TCR_RGN_NC		0
+#define ARM_LPAE_TCR_RGN_WBWA		1
+#define ARM_LPAE_TCR_RGN_WT		2
+#define ARM_LPAE_TCR_RGN_WB		3
+
+#define ARM_LPAE_TCR_SL0_SHIFT		6
+#define ARM_LPAE_TCR_SL0_MASK		0x3
+
+#define ARM_LPAE_TCR_T0SZ_SHIFT		0
+#define ARM_LPAE_TCR_SZ_MASK		0xf
+
+#define ARM_LPAE_TCR_PS_SHIFT		16
+#define ARM_LPAE_TCR_PS_MASK		0x7
+
+#define ARM_LPAE_TCR_IPS_SHIFT		32
+#define ARM_LPAE_TCR_IPS_MASK		0x7
+
+#define ARM_LPAE_TCR_PS_32_BIT		0x0ULL
+#define ARM_LPAE_TCR_PS_36_BIT		0x1ULL
+#define ARM_LPAE_TCR_PS_40_BIT		0x2ULL
+#define ARM_LPAE_TCR_PS_42_BIT		0x3ULL
+#define ARM_LPAE_TCR_PS_44_BIT		0x4ULL
+#define ARM_LPAE_TCR_PS_48_BIT		0x5ULL
+
+#define ARM_LPAE_MAIR_ATTR_SHIFT(n)	((n) << 3)
+#define ARM_LPAE_MAIR_ATTR_MASK		0xff
+#define ARM_LPAE_MAIR_ATTR_DEVICE	0x04
+#define ARM_LPAE_MAIR_ATTR_NC		0x44
+#define ARM_LPAE_MAIR_ATTR_WBRWA	0xff
+#define ARM_LPAE_MAIR_ATTR_IDX_NC	0
+#define ARM_LPAE_MAIR_ATTR_IDX_CACHE	1
+#define ARM_LPAE_MAIR_ATTR_IDX_DEV	2
+
+/* IOPTE accessors */
+#define iopte_deref(pte,d)					\
+	(__va((pte) & ((1ULL << ARM_LPAE_MAX_ADDR_BITS) - 1)	\
+	& ~((1ULL << (d)->pg_shift) - 1)))
+
+#define iopte_type(pte,l)					\
+	(((pte) >> ARM_LPAE_PTE_TYPE_SHIFT) & ARM_LPAE_PTE_TYPE_MASK)
+
+#define iopte_prot(pte)	((pte) & ARM_LPAE_PTE_ATTR_MASK)
+
+#define iopte_leaf(pte,l)					\
+	(l == (ARM_LPAE_MAX_LEVELS - 1) ?			\
+		(iopte_type(pte,l) == ARM_LPAE_PTE_TYPE_PAGE) :	\
+		(iopte_type(pte,l) == ARM_LPAE_PTE_TYPE_BLOCK))
+
+#define iopte_to_pfn(pte,d)					\
+	(((pte) & ((1ULL << ARM_LPAE_MAX_ADDR_BITS) - 1)) >> (d)->pg_shift)
+
+#define pfn_to_iopte(pfn,d)					\
+	(((pfn) << (d)->pg_shift) & ((1ULL << ARM_LPAE_MAX_ADDR_BITS) - 1))
+
+struct arm_lpae_io_pgtable {
+	struct io_pgtable	iop;
+
+	int			levels;
+	size_t			pgd_size;
+	unsigned long		pg_shift;
+	unsigned long		bits_per_level;
+
+	void			*pgd;
+};
+
+typedef u64 arm_lpae_iopte;
+
+static int arm_lpae_init_pte(struct arm_lpae_io_pgtable *data,
+			     unsigned long iova, phys_addr_t paddr,
+			     arm_lpae_iopte prot, int lvl,
+			     arm_lpae_iopte *ptep)
+{
+	arm_lpae_iopte pte = prot;
+
+	/* We require an unmap first */
+	if (WARN_ON(iopte_leaf(*ptep, lvl)))
+		return -EEXIST;
+
+	if (lvl == ARM_LPAE_MAX_LEVELS - 1)
+		pte |= ARM_LPAE_PTE_TYPE_PAGE;
+	else
+		pte |= ARM_LPAE_PTE_TYPE_BLOCK;
+
+	pte |= ARM_LPAE_PTE_AF | ARM_LPAE_PTE_SH_IS;
+	pte |= pfn_to_iopte(paddr >> data->pg_shift, data);
+
+	*ptep = pte;
+	data->iop.cfg.tlb->flush_pgtable(ptep, sizeof(*ptep), data->iop.cookie);
+	return 0;
+}
+
+static int __arm_lpae_map(struct arm_lpae_io_pgtable *data, unsigned long iova,
+			  phys_addr_t paddr, size_t size, arm_lpae_iopte prot,
+			  int lvl, arm_lpae_iopte *ptep)
+{
+	arm_lpae_iopte *cptep, pte;
+	void *cookie = data->iop.cookie;
+	size_t block_size = ARM_LPAE_BLOCK_SIZE(lvl, data);
+
+	/* Find our entry at the current level */
+	ptep += ARM_LPAE_LVL_IDX(iova, lvl, data);
+
+	/* If we can install a leaf entry at this level, then do so */
+	if (size == block_size && (size & data->iop.cfg.pgsize_bitmap))
+		return arm_lpae_init_pte(data, iova, paddr, prot, lvl, ptep);
+
+	/* We can't allocate tables at the final level */
+	if (WARN_ON(lvl >= ARM_LPAE_MAX_LEVELS - 1))
+		return -EINVAL;
+
+	/* Grab a pointer to the next level */
+	pte = *ptep;
+	if (!pte) {
+		cptep = alloc_pages_exact(1UL << data->pg_shift,
+					 GFP_ATOMIC | __GFP_ZERO);
+		if (!cptep)
+			return -ENOMEM;
+
+		data->iop.cfg.tlb->flush_pgtable(cptep, 1UL << data->pg_shift,
+						 cookie);
+		pte = __pa(cptep) | ARM_LPAE_PTE_TYPE_TABLE;
+		*ptep = pte;
+		data->iop.cfg.tlb->flush_pgtable(ptep, sizeof(*ptep), cookie);
+	} else {
+		cptep = iopte_deref(pte, data);
+	}
+
+	/* Rinse, repeat */
+	return __arm_lpae_map(data, iova, paddr, size, prot, lvl + 1, cptep);
+}
+
+static arm_lpae_iopte arm_lpae_prot_to_pte(struct arm_lpae_io_pgtable *data,
+					   int prot)
+{
+	arm_lpae_iopte pte;
+
+	if (data->iop.fmt == ARM_64_LPAE_S1 ||
+	    data->iop.fmt == ARM_32_LPAE_S1) {
+		pte = ARM_LPAE_PTE_AP_UNPRIV | ARM_LPAE_PTE_nG;
+
+		if (!(prot & IOMMU_WRITE) && (prot & IOMMU_READ))
+			pte |= ARM_LPAE_PTE_AP_RDONLY;
+
+		if (prot & IOMMU_CACHE)
+			pte |= (ARM_LPAE_MAIR_ATTR_IDX_CACHE
+				<< ARM_LPAE_PTE_ATTRINDX_SHIFT);
+	} else {
+		pte = ARM_LPAE_PTE_HAP_FAULT;
+		if (prot & IOMMU_READ)
+			pte |= ARM_LPAE_PTE_HAP_READ;
+		if (prot & IOMMU_WRITE)
+			pte |= ARM_LPAE_PTE_HAP_WRITE;
+		if (prot & IOMMU_CACHE)
+			pte |= ARM_LPAE_PTE_MEMATTR_OIWB;
+		else
+			pte |= ARM_LPAE_PTE_MEMATTR_NC;
+	}
+
+	if (prot & IOMMU_NOEXEC)
+		pte |= ARM_LPAE_PTE_XN;
+
+	return pte;
+}
+
+static int arm_lpae_map(struct io_pgtable_ops *ops, unsigned long iova,
+			phys_addr_t paddr, size_t size, int iommu_prot)
+{
+	struct arm_lpae_io_pgtable *data = io_pgtable_ops_to_data(ops);
+	arm_lpae_iopte *ptep = data->pgd;
+	int lvl = ARM_LPAE_START_LVL(data);
+	arm_lpae_iopte prot;
+
+	/* If no access, then nothing to do */
+	if (!(iommu_prot & (IOMMU_READ | IOMMU_WRITE)))
+		return 0;
+
+	prot = arm_lpae_prot_to_pte(data, iommu_prot);
+	return __arm_lpae_map(data, iova, paddr, size, prot, lvl, ptep);
+}
+
+static void __arm_lpae_free_pgtable(struct arm_lpae_io_pgtable *data, int lvl,
+				    arm_lpae_iopte *ptep)
+{
+	arm_lpae_iopte *start, *end;
+	unsigned long table_size;
+
+	/* Only leaf entries at the last level */
+	if (lvl == ARM_LPAE_MAX_LEVELS - 1)
+		return;
+
+	if (lvl == ARM_LPAE_START_LVL(data))
+		table_size = data->pgd_size;
+	else
+		table_size = 1UL << data->pg_shift;
+
+	start = ptep;
+	end = (void *)ptep + table_size;
+
+	while (ptep != end) {
+		arm_lpae_iopte pte = *ptep++;
+
+		if (!pte || iopte_leaf(pte, lvl))
+			continue;
+
+		__arm_lpae_free_pgtable(data, lvl + 1, iopte_deref(pte, data));
+	}
+
+	free_pages_exact(start, table_size);
+}
+
+static void arm_lpae_free_pgtable(struct io_pgtable *iop)
+{
+	struct arm_lpae_io_pgtable *data = io_pgtable_to_data(iop);
+
+	__arm_lpae_free_pgtable(data, ARM_LPAE_START_LVL(data), data->pgd);
+	kfree(data);
+}
+
+static int arm_lpae_split_blk_unmap(struct arm_lpae_io_pgtable *data,
+				    unsigned long iova, size_t size,
+				    arm_lpae_iopte prot, int lvl,
+				    arm_lpae_iopte *ptep, size_t blk_size)
+{
+	unsigned long blk_start, blk_end;
+	phys_addr_t blk_paddr;
+	arm_lpae_iopte table = 0;
+	void *cookie = data->iop.cookie;
+	const struct iommu_gather_ops *tlb = data->iop.cfg.tlb;
+
+	blk_start = iova & ~(blk_size - 1);
+	blk_end = blk_start + blk_size;
+	blk_paddr = iopte_to_pfn(*ptep, data) << data->pg_shift;
+
+	for (; blk_start < blk_end; blk_start += size, blk_paddr += size) {
+		arm_lpae_iopte *tablep;
+
+		/* Unmap! */
+		if (blk_start == iova)
+			continue;
+
+		/* __arm_lpae_map expects a pointer to the start of the table */
+		tablep = &table - ARM_LPAE_LVL_IDX(blk_start, lvl, data);
+		if (__arm_lpae_map(data, blk_start, blk_paddr, size, prot, lvl,
+				   tablep) < 0) {
+			if (table) {
+				/* Free the table we allocated */
+				tablep = iopte_deref(table, data);
+				__arm_lpae_free_pgtable(data, lvl + 1, tablep);
+			}
+			return 0; /* Bytes unmapped */
+		}
+	}
+
+	*ptep = table;
+	tlb->flush_pgtable(ptep, sizeof(*ptep), cookie);
+	iova &= ~(blk_size - 1);
+	tlb->tlb_add_flush(iova, blk_size, true, cookie);
+	return size;
+}
+
+static int __arm_lpae_unmap(struct arm_lpae_io_pgtable *data,
+			    unsigned long iova, size_t size, int lvl,
+			    arm_lpae_iopte *ptep)
+{
+	arm_lpae_iopte pte;
+	const struct iommu_gather_ops *tlb = data->iop.cfg.tlb;
+	void *cookie = data->iop.cookie;
+	size_t blk_size = ARM_LPAE_BLOCK_SIZE(lvl, data);
+
+	ptep += ARM_LPAE_LVL_IDX(iova, lvl, data);
+	pte = *ptep;
+
+	/* Something went horribly wrong and we ran out of page table */
+	if (WARN_ON(!pte || (lvl == ARM_LPAE_MAX_LEVELS)))
+		return 0;
+
+	/* If the size matches this level, we're in the right place */
+	if (size == blk_size) {
+		*ptep = 0;
+		tlb->flush_pgtable(ptep, sizeof(*ptep), cookie);
+
+		if (!iopte_leaf(pte, lvl)) {
+			/* Also flush any partial walks */
+			tlb->tlb_add_flush(iova, size, false, cookie);
+			tlb->tlb_sync(data->iop.cookie);
+			ptep = iopte_deref(pte, data);
+			__arm_lpae_free_pgtable(data, lvl + 1, ptep);
+		} else {
+			tlb->tlb_add_flush(iova, size, true, cookie);
+		}
+
+		return size;
+	} else if (iopte_leaf(pte, lvl)) {
+		/*
+		 * Insert a table at the next level to map the old region,
+		 * minus the part we want to unmap
+		 */
+		return arm_lpae_split_blk_unmap(data, iova, size,
+						iopte_prot(pte), lvl, ptep,
+						blk_size);
+	}
+
+	/* Keep on walkin' */
+	ptep = iopte_deref(pte, data);
+	return __arm_lpae_unmap(data, iova, size, lvl + 1, ptep);
+}
+
+static int arm_lpae_unmap(struct io_pgtable_ops *ops, unsigned long iova,
+			  size_t size)
+{
+	size_t unmapped;
+	struct arm_lpae_io_pgtable *data = io_pgtable_ops_to_data(ops);
+	struct io_pgtable *iop = &data->iop;
+	arm_lpae_iopte *ptep = data->pgd;
+	int lvl = ARM_LPAE_START_LVL(data);
+
+	unmapped = __arm_lpae_unmap(data, iova, size, lvl, ptep);
+	if (unmapped)
+		iop->cfg.tlb->tlb_sync(iop->cookie);
+
+	return unmapped;
+}
+
+static phys_addr_t arm_lpae_iova_to_phys(struct io_pgtable_ops *ops,
+					 unsigned long iova)
+{
+	struct arm_lpae_io_pgtable *data = io_pgtable_ops_to_data(ops);
+	arm_lpae_iopte pte, *ptep = data->pgd;
+	int lvl = ARM_LPAE_START_LVL(data);
+
+	do {
+		/* Valid IOPTE pointer? */
+		if (!ptep)
+			return 0;
+
+		/* Grab the IOPTE we're interested in */
+		pte = *(ptep + ARM_LPAE_LVL_IDX(iova, lvl, data));
+
+		/* Valid entry? */
+		if (!pte)
+			return 0;
+
+		/* Leaf entry? */
+		if (iopte_leaf(pte,lvl))
+			goto found_translation;
+
+		/* Take it to the next level */
+		ptep = iopte_deref(pte, data);
+	} while (++lvl < ARM_LPAE_MAX_LEVELS);
+
+	/* Ran out of page tables to walk */
+	return 0;
+
+found_translation:
+	iova &= ((1 << data->pg_shift) - 1);
+	return ((phys_addr_t)iopte_to_pfn(pte,data) << data->pg_shift) | iova;
+}
+
+static void arm_lpae_restrict_pgsizes(struct io_pgtable_cfg *cfg)
+{
+	unsigned long granule;
+
+	/*
+	 * We need to restrict the supported page sizes to match the
+	 * translation regime for a particular granule. Aim to match
+	 * the CPU page size if possible, otherwise prefer smaller sizes.
+	 * While we're at it, restrict the block sizes to match the
+	 * chosen granule.
+	 */
+	if (cfg->pgsize_bitmap & PAGE_SIZE)
+		granule = PAGE_SIZE;
+	else if (cfg->pgsize_bitmap & ~PAGE_MASK)
+		granule = 1UL << __fls(cfg->pgsize_bitmap & ~PAGE_MASK);
+	else if (cfg->pgsize_bitmap & PAGE_MASK)
+		granule = 1UL << __ffs(cfg->pgsize_bitmap & PAGE_MASK);
+	else
+		granule = 0;
+
+	switch (granule) {
+	case SZ_4K:
+		cfg->pgsize_bitmap &= (SZ_4K | SZ_2M | SZ_1G);
+		break;
+	case SZ_16K:
+		cfg->pgsize_bitmap &= (SZ_16K | SZ_32M);
+		break;
+	case SZ_64K:
+		cfg->pgsize_bitmap &= (SZ_64K | SZ_512M);
+		break;
+	default:
+		cfg->pgsize_bitmap = 0;
+	}
+}
+
+static struct arm_lpae_io_pgtable *
+arm_lpae_alloc_pgtable(struct io_pgtable_cfg *cfg)
+{
+	unsigned long va_bits, pgd_bits;
+	struct arm_lpae_io_pgtable *data;
+
+	arm_lpae_restrict_pgsizes(cfg);
+
+	if (!(cfg->pgsize_bitmap & (SZ_4K | SZ_16K | SZ_64K)))
+		return NULL;
+
+	if (cfg->ias > ARM_LPAE_MAX_ADDR_BITS)
+		return NULL;
+
+	if (cfg->oas > ARM_LPAE_MAX_ADDR_BITS)
+		return NULL;
+
+	data = kmalloc(sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return NULL;
+
+	data->pg_shift = __ffs(cfg->pgsize_bitmap);
+	data->bits_per_level = data->pg_shift - ilog2(sizeof(arm_lpae_iopte));
+
+	va_bits = cfg->ias - data->pg_shift;
+	data->levels = DIV_ROUND_UP(va_bits, data->bits_per_level);
+
+	/* Calculate the actual size of our pgd (without concatenation) */
+	pgd_bits = va_bits - (data->bits_per_level * (data->levels - 1));
+	data->pgd_size = 1UL << (pgd_bits + ilog2(sizeof(arm_lpae_iopte)));
+
+	data->iop.ops = (struct io_pgtable_ops) {
+		.map		= arm_lpae_map,
+		.unmap		= arm_lpae_unmap,
+		.iova_to_phys	= arm_lpae_iova_to_phys,
+	};
+
+	return data;
+}
+
+static struct io_pgtable *
+arm_64_lpae_alloc_pgtable_s1(struct io_pgtable_cfg *cfg, void *cookie)
+{
+	u64 reg;
+	struct arm_lpae_io_pgtable *data = arm_lpae_alloc_pgtable(cfg);
+
+	if (!data)
+		return NULL;
+
+	/* TCR */
+	reg = (ARM_LPAE_TCR_SH_IS << ARM_LPAE_TCR_SH0_SHIFT) |
+	      (ARM_LPAE_TCR_RGN_WBWA << ARM_LPAE_TCR_IRGN0_SHIFT) |
+	      (ARM_LPAE_TCR_RGN_WBWA << ARM_LPAE_TCR_ORGN0_SHIFT);
+
+	switch (1 << data->pg_shift) {
+	case SZ_4K:
+		reg |= ARM_LPAE_TCR_TG0_4K;
+		break;
+	case SZ_16K:
+		reg |= ARM_LPAE_TCR_TG0_16K;
+		break;
+	case SZ_64K:
+		reg |= ARM_LPAE_TCR_TG0_64K;
+		break;
+	}
+
+	switch (cfg->oas) {
+	case 32:
+		reg |= (ARM_LPAE_TCR_PS_32_BIT << ARM_LPAE_TCR_IPS_SHIFT);
+		break;
+	case 36:
+		reg |= (ARM_LPAE_TCR_PS_36_BIT << ARM_LPAE_TCR_IPS_SHIFT);
+		break;
+	case 40:
+		reg |= (ARM_LPAE_TCR_PS_40_BIT << ARM_LPAE_TCR_IPS_SHIFT);
+		break;
+	case 42:
+		reg |= (ARM_LPAE_TCR_PS_42_BIT << ARM_LPAE_TCR_IPS_SHIFT);
+		break;
+	case 44:
+		reg |= (ARM_LPAE_TCR_PS_44_BIT << ARM_LPAE_TCR_IPS_SHIFT);
+		break;
+	case 48:
+		reg |= (ARM_LPAE_TCR_PS_48_BIT << ARM_LPAE_TCR_IPS_SHIFT);
+		break;
+	default:
+		goto out_free_data;
+	}
+
+	reg |= (64ULL - cfg->ias) << ARM_LPAE_TCR_T0SZ_SHIFT;
+	cfg->arm_lpae_s1_cfg.tcr = reg;
+
+	/* MAIRs */
+	reg = (ARM_LPAE_MAIR_ATTR_NC
+	       << ARM_LPAE_MAIR_ATTR_SHIFT(ARM_LPAE_MAIR_ATTR_IDX_NC)) |
+	      (ARM_LPAE_MAIR_ATTR_WBRWA
+	       << ARM_LPAE_MAIR_ATTR_SHIFT(ARM_LPAE_MAIR_ATTR_IDX_CACHE)) |
+	      (ARM_LPAE_MAIR_ATTR_DEVICE
+	       << ARM_LPAE_MAIR_ATTR_SHIFT(ARM_LPAE_MAIR_ATTR_IDX_DEV));
+
+	cfg->arm_lpae_s1_cfg.mair[0] = reg;
+	cfg->arm_lpae_s1_cfg.mair[1] = 0;
+
+	/* Looking good; allocate a pgd */
+	data->pgd = alloc_pages_exact(data->pgd_size, GFP_KERNEL | __GFP_ZERO);
+	if (!data->pgd)
+		goto out_free_data;
+
+	cfg->tlb->flush_pgtable(data->pgd, data->pgd_size, cookie);
+
+	/* TTBRs */
+	cfg->arm_lpae_s1_cfg.ttbr[0] = virt_to_phys(data->pgd);
+	cfg->arm_lpae_s1_cfg.ttbr[1] = 0;
+	return &data->iop;
+
+out_free_data:
+	kfree(data);
+	return NULL;
+}
+
+static struct io_pgtable *
+arm_64_lpae_alloc_pgtable_s2(struct io_pgtable_cfg *cfg, void *cookie)
+{
+	u64 reg, sl;
+	struct arm_lpae_io_pgtable *data = arm_lpae_alloc_pgtable(cfg);
+
+	if (!data)
+		return NULL;
+
+	/*
+	 * Concatenate PGDs at level 1 if possible in order to reduce
+	 * the depth of the stage-2 walk.
+	 */
+	if (data->levels == ARM_LPAE_MAX_LEVELS) {
+		unsigned long pgd_pages;
+
+		pgd_pages = data->pgd_size >> ilog2(sizeof(arm_lpae_iopte));
+		if (pgd_pages <= ARM_LPAE_S2_MAX_CONCAT_PAGES) {
+			data->pgd_size = pgd_pages << data->pg_shift;
+			data->levels--;
+		}
+	}
+
+	/* VTCR */
+	reg = ARM_64_LPAE_S2_TCR_RES1 |
+	     (ARM_LPAE_TCR_SH_IS << ARM_LPAE_TCR_SH0_SHIFT) |
+	     (ARM_LPAE_TCR_RGN_WBWA << ARM_LPAE_TCR_IRGN0_SHIFT) |
+	     (ARM_LPAE_TCR_RGN_WBWA << ARM_LPAE_TCR_ORGN0_SHIFT);
+
+	sl = ARM_LPAE_START_LVL(data);
+
+	switch (1 << data->pg_shift) {
+	case SZ_4K:
+		reg |= ARM_LPAE_TCR_TG0_4K;
+		sl++; /* SL0 format is different for 4K granule size */
+		break;
+	case SZ_16K:
+		reg |= ARM_LPAE_TCR_TG0_16K;
+		break;
+	case SZ_64K:
+		reg |= ARM_LPAE_TCR_TG0_64K;
+		break;
+	}
+
+	switch (cfg->oas) {
+	case 32:
+		reg |= (ARM_LPAE_TCR_PS_32_BIT << ARM_LPAE_TCR_PS_SHIFT);
+		break;
+	case 36:
+		reg |= (ARM_LPAE_TCR_PS_36_BIT << ARM_LPAE_TCR_PS_SHIFT);
+		break;
+	case 40:
+		reg |= (ARM_LPAE_TCR_PS_40_BIT << ARM_LPAE_TCR_PS_SHIFT);
+		break;
+	case 42:
+		reg |= (ARM_LPAE_TCR_PS_42_BIT << ARM_LPAE_TCR_PS_SHIFT);
+		break;
+	case 44:
+		reg |= (ARM_LPAE_TCR_PS_44_BIT << ARM_LPAE_TCR_PS_SHIFT);
+		break;
+	case 48:
+		reg |= (ARM_LPAE_TCR_PS_48_BIT << ARM_LPAE_TCR_PS_SHIFT);
+		break;
+	default:
+		goto out_free_data;
+	}
+
+	reg |= (64ULL - cfg->ias) << ARM_LPAE_TCR_T0SZ_SHIFT;
+	reg |= (~sl & ARM_LPAE_TCR_SL0_MASK) << ARM_LPAE_TCR_SL0_SHIFT;
+	cfg->arm_lpae_s2_cfg.vtcr = reg;
+
+	/* Allocate pgd pages */
+	data->pgd = alloc_pages_exact(data->pgd_size, GFP_KERNEL | __GFP_ZERO);
+	if (!data->pgd)
+		goto out_free_data;
+
+	cfg->tlb->flush_pgtable(data->pgd, data->pgd_size, cookie);
+
+	/* VTTBR */
+	cfg->arm_lpae_s2_cfg.vttbr = virt_to_phys(data->pgd);
+	return &data->iop;
+
+out_free_data:
+	kfree(data);
+	return NULL;
+}
+
+static struct io_pgtable *
+arm_32_lpae_alloc_pgtable_s1(struct io_pgtable_cfg *cfg, void *cookie)
+{
+	struct io_pgtable *iop;
+
+	if (cfg->ias > 32 || cfg->oas > 40)
+		return NULL;
+
+	cfg->pgsize_bitmap &= (SZ_4K | SZ_2M | SZ_1G);
+	iop = arm_64_lpae_alloc_pgtable_s1(cfg, cookie);
+	if (iop) {
+		cfg->arm_lpae_s1_cfg.tcr |= ARM_32_LPAE_TCR_EAE;
+		cfg->arm_lpae_s1_cfg.tcr &= 0xffffffff;
+	}
+
+	return iop;
+}
+
+static struct io_pgtable *
+arm_32_lpae_alloc_pgtable_s2(struct io_pgtable_cfg *cfg, void *cookie)
+{
+	struct io_pgtable *iop;
+
+	if (cfg->ias > 40 || cfg->oas > 40)
+		return NULL;
+
+	cfg->pgsize_bitmap &= (SZ_4K | SZ_2M | SZ_1G);
+	iop = arm_64_lpae_alloc_pgtable_s2(cfg, cookie);
+	if (iop)
+		cfg->arm_lpae_s2_cfg.vtcr &= 0xffffffff;
+
+	return iop;
+}
+
+struct io_pgtable_init_fns io_pgtable_arm_64_lpae_s1_init_fns = {
+	.alloc	= arm_64_lpae_alloc_pgtable_s1,
+	.free	= arm_lpae_free_pgtable,
+};
+
+struct io_pgtable_init_fns io_pgtable_arm_64_lpae_s2_init_fns = {
+	.alloc	= arm_64_lpae_alloc_pgtable_s2,
+	.free	= arm_lpae_free_pgtable,
+};
+
+struct io_pgtable_init_fns io_pgtable_arm_32_lpae_s1_init_fns = {
+	.alloc	= arm_32_lpae_alloc_pgtable_s1,
+	.free	= arm_lpae_free_pgtable,
+};
+
+struct io_pgtable_init_fns io_pgtable_arm_32_lpae_s2_init_fns = {
+	.alloc	= arm_32_lpae_alloc_pgtable_s2,
+	.free	= arm_lpae_free_pgtable,
+};