Subject: [PATCH 2/4] iommu: add ARM LPAE page table allocator

From: [email-masked] (Laurent Pinchart)
Date: Mon, 01 Dec 2014 01:29:46 +0200

Hi Will,

Thank you for the patch.

On Thursday 27 November 2014 11:51:16 Will Deacon wrote:
> 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.
> 
> Signed-off-by: Will Deacon <[email-masked]>
> ---
>  MAINTAINERS                    |   1 +
>  drivers/iommu/Kconfig          |   9 +
>  drivers/iommu/Makefile         |   1 +
>  drivers/iommu/io-pgtable-arm.c | 735 ++++++++++++++++++++++++++++++++++++++
>  drivers/iommu/io-pgtable.c     |   7 +
>  drivers/iommu/io-pgtable.h     |  12 +
>  6 files changed, 765 insertions(+)
>  create mode 100644 drivers/iommu/io-pgtable-arm.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 0ff630de8a6d..d3ca31b7c960 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -1562,6 +1562,7 @@ M:	Will Deacon <[email-masked]>
>  L:	linux-arm-kernel at lists.infradead.org (moderated for non-subscribers)
>  S:	Maintained
>  F:	drivers/iommu/arm-smmu.c
> +F:	drivers/iommu/io-pgtable-arm.c
> 
>  ARM64 PORT (AARCH64 ARCHITECTURE)
>  M:	Catalin Marinas <[email-masked]>
> diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
> index 0f10554e7114..e1742a0146f8 100644
> --- a/drivers/iommu/Kconfig
> +++ b/drivers/iommu/Kconfig
> @@ -19,6 +19,15 @@ menu "Generic IOMMU Pagetable Support"
>  config IOMMU_IO_PGTABLE
>  	bool
> 
> +config IOMMU_IO_PGTABLE_LPAE
> +	bool "ARMv7/v8 Long Descriptor Format"
> +	select IOMMU_IO_PGTABLE
> +	help
> +	  Enable support for the ARM long descriptor pagetable format.
> +	  This allocator supports 4K/2M/1G, 16K/32M and 64K/512M page
> +	  sizes at both stage-1 and stage-2, as well as address spaces
> +	  up to 48-bits in size.
> +
>  endmenu
> 
>  config OF_IOMMU
> diff --git a/drivers/iommu/Makefile b/drivers/iommu/Makefile
> index aff244c78181..269cdd82b672 100644
> --- a/drivers/iommu/Makefile
> +++ b/drivers/iommu/Makefile
> @@ -2,6 +2,7 @@ obj-$(CONFIG_IOMMU_API) += iommu.o
>  obj-$(CONFIG_IOMMU_API) += iommu-traces.o
>  obj-$(CONFIG_IOMMU_API) += iommu-sysfs.o
>  obj-$(CONFIG_IOMMU_IO_PGTABLE) += io-pgtable.o
> +obj-$(CONFIG_IOMMU_IO_PGTABLE_LPAE) += io-pgtable-arm.o
>  obj-$(CONFIG_OF_IOMMU)	+= of_iommu.o
>  obj-$(CONFIG_MSM_IOMMU) += msm_iommu.o msm_iommu_dev.o
>  obj-$(CONFIG_AMD_IOMMU) += amd_iommu.o amd_iommu_init.o
> diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c
> new file mode 100644
> index 000000000000..9dbaa2e48424
> --- /dev/null
> +++ b/drivers/iommu/io-pgtable-arm.c
> @@ -0,0 +1,735 @@
> +/*
> + * 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 <[email-masked]>
> + */
> +
> +#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)
> +
> +/*
> + * 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((d)->pages_per_pgd) : 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_LPAE_TCR_EAE		(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;
> +	int			pages_per_pgd;
> +	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 (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_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);

In my case I'll need to manage the NS bit (here and when allocating tables in 
__arm_lpae_map). The exact requirements are not exactly clear@the moment 
I'm afraid, the datasheet doesn't clearly document secure behaviour, but tests 
showed that setting the NS was necessary.

Given that arm_lpae_init_pte() will unconditionally set the AF and SH_IS bits 
you could set them here too, but that shouldn't make a big difference.

> +	} 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;

Shouldn't this create a faulting entry instead ?

> +	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;
> +
> +	table_size = 1UL << data->pg_shift;
> +	if (lvl == ARM_LPAE_START_LVL(data))
> +		table_size *= data->pages_per_pgd;
> +
> +	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;
> +	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;
> +	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;
> +	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->pages_per_pgd = 1;
> +	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);
> +
> +	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_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_EAE |
> +	     (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(1UL << data->pg_shift,
> +				      GFP_KERNEL | __GFP_ZERO);

data->pg_shift is computed as __ffs(cfg->pgsize_bitmap). 1UL << data->pg_shift 
will thus be equal to the smallest page size supported by the IOMMU. This will 
thus allocate 4kB, 16kB or 64kB depending on the IOMMU configuration. However, 
if I'm not mistaken the top-level directory needs to store one entry per 
largest supported page size. That's 4, 128 or 8 entries depending on the 
configuration. You're thus over-allocating.

> +	if (!data->pgd)
> +		goto out_free_data;
> +
> +	cfg->tlb->flush_pgtable(data->pgd, (1UL << data->pg_shift), 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_lpae_alloc_pgtable_s2(struct io_pgtable_cfg
> *cfg,
> +						    void *cookie)
> +{
> +	u64 reg, sl;
> +	size_t pgd_size;
> +	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_bits, pgd_pages;
> +		unsigned long va_bits = cfg->ias - data->pg_shift;
> +
> +		pgd_bits = data->bits_per_level * (data->levels - 1);
> +		pgd_pages = 1 << (va_bits - pgd_bits);
> +		if (pgd_pages <= ARM_LPAE_S2_MAX_CONCAT_PAGES) {
> +			data->pages_per_pgd = pgd_pages;
> +			data->levels--;
> +		}
> +	}
> +
> +	/* VTCR */
> +	reg = ARM_LPAE_TCR_EAE |
> +	     (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 */
> +	pgd_size = data->pages_per_pgd * (1UL << data->pg_shift);
> +	data->pgd = alloc_pages_exact(pgd_size, GFP_KERNEL | __GFP_ZERO);
> +	if (!data->pgd)
> +		goto out_free_data;
> +
> +	cfg->tlb->flush_pgtable(data->pgd, 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;
> +}
> +
> +struct io_pgtable_init_fns io_pgtable_arm_lpae_s1_init_fns = {
> +	.alloc	= arm_lpae_alloc_pgtable_s1,
> +	.free	= arm_lpae_free_pgtable,
> +};
> +
> +struct io_pgtable_init_fns io_pgtable_arm_lpae_s2_init_fns = {
> +	.alloc	= arm_lpae_alloc_pgtable_s2,
> +	.free	= arm_lpae_free_pgtable,
> +};
> diff --git a/drivers/iommu/io-pgtable.c b/drivers/iommu/io-pgtable.c
> index 82e39a0db94b..d0a2016efcb4 100644
> --- a/drivers/iommu/io-pgtable.c
> +++ b/drivers/iommu/io-pgtable.c
> @@ -25,8 +25,15 @@
> 
>  #include "io-pgtable.h"
> 
> +extern struct io_pgtable_init_fns io_pgtable_arm_lpae_s1_init_fns;
> +extern struct io_pgtable_init_fns io_pgtable_arm_lpae_s2_init_fns;
> +
>  static struct io_pgtable_init_fns
> *io_pgtable_init_table[IO_PGTABLE_NUM_FMTS] = {
> +#ifdef CONFIG_IOMMU_IO_PGTABLE_LPAE
> +	[ARM_LPAE_S1] = &io_pgtable_arm_lpae_s1_init_fns,
> +	[ARM_LPAE_S2] = &io_pgtable_arm_lpae_s2_init_fns,
> +#endif
>  };
> 
>  struct io_pgtable_ops *alloc_io_pgtable_ops(enum io_pgtable_fmt fmt,
> diff --git a/drivers/iommu/io-pgtable.h b/drivers/iommu/io-pgtable.h
> index 5ae75d9cae50..c1cff3d045db 100644
> --- a/drivers/iommu/io-pgtable.h
> +++ b/drivers/iommu/io-pgtable.h
> @@ -33,10 +33,22 @@ struct io_pgtable_cfg {
> 
>  	/* Low-level data specific to the table format */
>  	union {
> +		struct {
> +			u64	ttbr[2];
> +			u64	tcr;
> +			u64	mair[2];
> +		} arm_lpae_s1_cfg;
> +
> +		struct {
> +			u64	vttbr;
> +			u64	vtcr;
> +		} arm_lpae_s2_cfg;
>  	};
>  };
> 
>  enum io_pgtable_fmt {
> +	ARM_LPAE_S1,
> +	ARM_LPAE_S2,
>  	IO_PGTABLE_NUM_FMTS,
>  };

-- 
Regards,

Laurent Pinchart