iommu/io-pgtable: Add ARMv7 short descriptor support

Add a nearly-complete ARMv7 short descriptor implementation, omitting
only a few legacy and CPU-centric aspects which shouldn't be necessary
for IOMMU API use anyway.
Reviewed-by: Yong Wu <yong.wu@mediatek.com>
Tested-by: Yong Wu <yong.wu@mediatek.com>
Signed-off-by: Yong Wu <yong.wu@mediatek.com>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

drivers/iommu/Kconfig

@@ -39,6 +39,25 @@ config IOMMU_IO_PGTABLE_LPAE_SELFTEST
 
 	  If unsure, say N here.
 
+config IOMMU_IO_PGTABLE_ARMV7S
+	bool "ARMv7/v8 Short Descriptor Format"
+	select IOMMU_IO_PGTABLE
+	depends on HAS_DMA && (ARM || ARM64 || COMPILE_TEST)
+	help
+	  Enable support for the ARM Short-descriptor pagetable format.
+	  This supports 32-bit virtual and physical addresses mapped using
+	  2-level tables with 4KB pages/1MB sections, and contiguous entries
+	  for 64KB pages/16MB supersections if indicated by the IOMMU driver.
+
+config IOMMU_IO_PGTABLE_ARMV7S_SELFTEST
+	bool "ARMv7s selftests"
+	depends on IOMMU_IO_PGTABLE_ARMV7S
+	help
+	  Enable self-tests for ARMv7s page table allocator. This performs
+	  a series of page-table consistency checks during boot.
+
+	  If unsure, say N here.
+
 endmenu
 
 config IOMMU_IOVA

drivers/iommu/Makefile

@@ -3,6 +3,7 @@ obj-$(CONFIG_IOMMU_API) += iommu-traces.o
 obj-$(CONFIG_IOMMU_API) += iommu-sysfs.o
 obj-$(CONFIG_IOMMU_DMA) += dma-iommu.o
 obj-$(CONFIG_IOMMU_IO_PGTABLE) += io-pgtable.o
+obj-$(CONFIG_IOMMU_IO_PGTABLE_ARMV7S) += io-pgtable-arm-v7s.o
 obj-$(CONFIG_IOMMU_IO_PGTABLE_LPAE) += io-pgtable-arm.o
 obj-$(CONFIG_IOMMU_IOVA) += iova.o
 obj-$(CONFIG_OF_IOMMU)	+= of_iommu.o

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

+/*
+ * 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
+ *
+ * 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) 2014-2015 ARM Limited
+ * Copyright (c) 2014-2015 MediaTek Inc.
+ */
+
+#define pr_fmt(fmt)	"arm-v7s io-pgtable: " fmt
+
+#include <linux/dma-mapping.h>
+#include <linux/gfp.h>
+#include <linux/iommu.h>
+#include <linux/kernel.h>
+#include <linux/kmemleak.h>
+#include <linux/sizes.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+
+#include <asm/barrier.h>
+
+#include "io-pgtable.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. With some carefully-chosen coefficients we can
+ * hide the ugly inconsistencies behind these macros and at least let the
+ * rest of the code pretend to be somewhat sane.
+ */
+#define ARM_V7S_ADDR_BITS		32
+#define _ARM_V7S_LVL_BITS(lvl)		(16 - (lvl) * 4)
+#define ARM_V7S_LVL_SHIFT(lvl)		(ARM_V7S_ADDR_BITS - (4 + 8 * (lvl)))
+#define ARM_V7S_TABLE_SHIFT		10
+
+#define ARM_V7S_PTES_PER_LVL(lvl)	(1 << _ARM_V7S_LVL_BITS(lvl))
+#define ARM_V7S_TABLE_SIZE(lvl)						\
+	(ARM_V7S_PTES_PER_LVL(lvl) * 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)		(ARM_V7S_PTES_PER_LVL(lvl) - 1)
+#define ARM_V7S_LVL_IDX(addr, lvl)	({				\
+	int _l = lvl;							\
+	((u32)(addr) >> ARM_V7S_LVL_SHIFT(_l)) & _ARM_V7S_IDX_MASK(_l); \
+})
+
+/*
+ * 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) & 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)
+
+/* *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))
+
+#define ARM_V7S_TCR_PD1			BIT(5)
+
+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 dma_addr_t __arm_v7s_dma_addr(void *pages)
+{
+	return (dma_addr_t)virt_to_phys(pages);
+}
+
+static arm_v7s_iopte *iopte_deref(arm_v7s_iopte pte, int lvl)
+{
+	if (ARM_V7S_PTE_IS_TABLE(pte, lvl))
+		pte &= ARM_V7S_TABLE_MASK;
+	else
+		pte &= ARM_V7S_LVL_MASK(lvl);
+	return phys_to_virt(pte);
+}
+
+static void *__arm_v7s_alloc_table(int lvl, gfp_t gfp,
+				   struct arm_v7s_io_pgtable *data)
+{
+	struct device *dev = data->iop.cfg.iommu_dev;
+	dma_addr_t dma;
+	size_t size = ARM_V7S_TABLE_SIZE(lvl);
+	void *table = NULL;
+
+	if (lvl == 1)
+		table = (void *)__get_dma_pages(__GFP_ZERO, get_order(size));
+	else if (lvl == 2)
+		table = kmem_cache_zalloc(data->l2_tables, gfp);
+	if (table && !selftest_running) {
+		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 != virt_to_phys(table))
+			goto out_unmap;
+	}
+	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 device *dev = data->iop.cfg.iommu_dev;
+	size_t size = ARM_V7S_TABLE_SIZE(lvl);
+
+	if (!selftest_running)
+		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 (selftest_running)
+		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 |
+			    ARM_V7S_ATTR_TEX(1);
+
+	if (ap) {
+		pte |= ARM_V7S_PTE_AF | 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_CACHE)
+		pte |= ARM_V7S_ATTR_B | ARM_V7S_ATTR_C;
+
+	return pte;
+}
+
+static int arm_v7s_pte_to_prot(arm_v7s_iopte pte, int lvl)
+{
+	int prot = IOMMU_READ;
+
+	if (pte & (ARM_V7S_PTE_AP_RDONLY << ARM_V7S_ATTR_SHIFT(lvl)))
+		prot |= IOMMU_WRITE;
+	if (pte & ARM_V7S_ATTR_C)
+		prot |= IOMMU_CACHE;
+
+	return prot;
+}
+
+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 arm_v7s_iopte arm_v7s_cont_to_pte(arm_v7s_iopte pte, int lvl)
+{
+	if (lvl == 1) {
+		pte &= ~ARM_V7S_CONT_SECTION;
+	} else if (lvl == 2) {
+		arm_v7s_iopte xn = pte & BIT(ARM_V7S_CONT_PAGE_XN_SHIFT);
+		arm_v7s_iopte tex = pte & (ARM_V7S_CONT_PAGE_TEX_MASK <<
+					   ARM_V7S_CONT_PAGE_TEX_SHIFT);
+
+		pte ^= xn | tex | ARM_V7S_PTE_TYPE_CONT_PAGE;
+		pte |= (xn >> ARM_V7S_CONT_PAGE_XN_SHIFT) |
+		       (tex >> ARM_V7S_CONT_PAGE_TEX_SHIFT) |
+		       ARM_V7S_PTE_TYPE_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 int __arm_v7s_unmap(struct arm_v7s_io_pgtable *, 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 = arm_v7s_prot_to_pte(prot, lvl, cfg);
+	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);
+			if (WARN_ON(__arm_v7s_unmap(data, 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_PTE_TYPE_PAGE;
+	if (lvl == 1 && (cfg->quirks & IO_PGTABLE_QUIRK_ARM_NS))
+		pte |= ARM_V7S_ATTR_NS_SECTION;
+
+	if (num_entries > 1)
+		pte = arm_v7s_pte_to_cont(pte, lvl);
+
+	pte |= paddr & ARM_V7S_LVL_MASK(lvl);
+
+	__arm_v7s_set_pte(ptep, pte, num_entries, cfg);
+	return 0;
+}
+
+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)
+{
+	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);
+
+	/* 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 = *ptep;
+	if (!pte) {
+		cptep = __arm_v7s_alloc_table(lvl + 1, GFP_ATOMIC, data);
+		if (!cptep)
+			return -ENOMEM;
+
+		pte = virt_to_phys(cptep) | ARM_V7S_PTE_TYPE_TABLE;
+		if (cfg->quirks & IO_PGTABLE_QUIRK_ARM_NS)
+			pte |= ARM_V7S_ATTR_NS_TABLE;
+
+		__arm_v7s_set_pte(ptep, pte, 1, cfg);
+	} else {
+		cptep = iopte_deref(pte, lvl);
+	}
+
+	/* Rinse, repeat */
+	return __arm_v7s_map(data, iova, paddr, size, prot, lvl + 1, cptep);
+}
+
+static int arm_v7s_map(struct io_pgtable_ops *ops, unsigned long iova,
+			phys_addr_t paddr, size_t size, int prot)
+{
+	struct arm_v7s_io_pgtable *data = io_pgtable_ops_to_data(ops);
+	struct io_pgtable_cfg *cfg = &data->iop.cfg;
+	const struct iommu_gather_ops *tlb = cfg->tlb;
+	void *cookie = data->iop.cookie;
+	int ret;
+
+	/* If no access, then nothing to do */
+	if (!(prot & (IOMMU_READ | IOMMU_WRITE)))
+		return 0;
+
+	ret = __arm_v7s_map(data, iova, paddr, size, prot, 1, data->pgd);
+	/*
+	 * 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.
+	 */
+	if (cfg->quirks & IO_PGTABLE_QUIRK_TLBI_ON_MAP) {
+		tlb->tlb_add_flush(iova, size, ARM_V7S_BLOCK_SIZE(2), false,
+				   cookie);
+		tlb->tlb_sync(cookie);
+	} else {
+		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); i++) {
+		arm_v7s_iopte pte = data->pgd[i];
+
+		if (ARM_V7S_PTE_IS_TABLE(pte, 1))
+			__arm_v7s_free_table(iopte_deref(pte, 1), 2, data);
+	}
+	__arm_v7s_free_table(data->pgd, 1, data);
+	kmem_cache_destroy(data->l2_tables);
+	kfree(data);
+}
+
+static void arm_v7s_split_cont(struct arm_v7s_io_pgtable *data,
+			       unsigned long iova, int idx, int lvl,
+			       arm_v7s_iopte *ptep)
+{
+	struct io_pgtable_cfg *cfg = &data->iop.cfg;
+	void *cookie = data->iop.cookie;
+	arm_v7s_iopte pte;
+	size_t size = ARM_V7S_BLOCK_SIZE(lvl);
+	int i;
+
+	ptep -= idx & (ARM_V7S_CONT_PAGES - 1);
+	pte = arm_v7s_cont_to_pte(*ptep, lvl);
+	for (i = 0; i < ARM_V7S_CONT_PAGES; i++) {
+		ptep[i] = pte;
+		pte += size;
+	}
+
+	__arm_v7s_pte_sync(ptep, ARM_V7S_CONT_PAGES, cfg);
+
+	size *= ARM_V7S_CONT_PAGES;
+	cfg->tlb->tlb_add_flush(iova, size, size, true, cookie);
+	cfg->tlb->tlb_sync(cookie);
+}
+
+static int arm_v7s_split_blk_unmap(struct arm_v7s_io_pgtable *data,
+				   unsigned long iova, size_t size,
+				   arm_v7s_iopte *ptep)
+{
+	unsigned long blk_start, blk_end, blk_size;
+	phys_addr_t blk_paddr;
+	arm_v7s_iopte table = 0;
+	struct io_pgtable_cfg *cfg = &data->iop.cfg;
+	int prot = arm_v7s_pte_to_prot(*ptep, 1);
+
+	blk_size = ARM_V7S_BLOCK_SIZE(1);
+	blk_start = iova & ARM_V7S_LVL_MASK(1);
+	blk_end = blk_start + ARM_V7S_BLOCK_SIZE(1);
+	blk_paddr = *ptep & ARM_V7S_LVL_MASK(1);
+
+	for (; blk_start < blk_end; blk_start += size, blk_paddr += size) {
+		arm_v7s_iopte *tablep;
+
+		/* Unmap! */
+		if (blk_start == iova)
+			continue;
+
+		/* __arm_v7s_map expects a pointer to the start of the table */
+		tablep = &table - ARM_V7S_LVL_IDX(blk_start, 1);
+		if (__arm_v7s_map(data, blk_start, blk_paddr, size, prot, 1,
+				  tablep) < 0) {
+			if (table) {
+				/* Free the table we allocated */
+				tablep = iopte_deref(table, 1);
+				__arm_v7s_free_table(tablep, 2, data);
+			}
+			return 0; /* Bytes unmapped */
+		}
+	}
+
+	__arm_v7s_set_pte(ptep, table, 1, cfg);
+	iova &= ~(blk_size - 1);
+	cfg->tlb->tlb_add_flush(iova, blk_size, blk_size, true, data->iop.cookie);
+	return size;
+}
+
+static int __arm_v7s_unmap(struct arm_v7s_io_pgtable *data,
+			    unsigned long iova, size_t size, int lvl,
+			    arm_v7s_iopte *ptep)
+{
+	arm_v7s_iopte pte[ARM_V7S_CONT_PAGES];
+	struct io_pgtable_cfg *cfg = &data->iop.cfg;
+	const struct iommu_gather_ops *tlb = cfg->tlb;
+	void *cookie = data->iop.cookie;
+	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);
+	ptep += idx;
+	do {
+		if (WARN_ON(!ARM_V7S_PTE_IS_VALID(ptep[i])))
+			return 0;
+		pte[i] = ptep[i];
+	} 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.
+	 */
+	if (num_entries <= 1 && arm_v7s_pte_is_cont(pte[0], lvl))
+		arm_v7s_split_cont(data, iova, idx, lvl, ptep);
+
+	/* 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, cfg);
+
+		for (i = 0; i < num_entries; i++) {
+			if (ARM_V7S_PTE_IS_TABLE(pte[i], lvl)) {
+				/* Also flush any partial walks */
+				tlb->tlb_add_flush(iova, blk_size,
+						   ARM_V7S_BLOCK_SIZE(lvl + 1),
+						   false, cookie);
+				tlb->tlb_sync(cookie);
+				ptep = iopte_deref(pte[i], lvl);
+				__arm_v7s_free_table(ptep, lvl + 1, data);
+			} else {
+				tlb->tlb_add_flush(iova, blk_size, blk_size,
+						   true, cookie);
+			}
+			iova += blk_size;
+		}
+		return size;
+	} else if (lvl == 1 && !ARM_V7S_PTE_IS_TABLE(pte[0], lvl)) {
+		/*
+		 * Insert a table at the next level to map the old region,
+		 * minus the part we want to unmap
+		 */
+		return arm_v7s_split_blk_unmap(data, iova, size, ptep);
+	}
+
+	/* Keep on walkin' */
+	ptep = iopte_deref(pte[0], lvl);
+	return __arm_v7s_unmap(data, iova, size, lvl + 1, ptep);
+}
+
+static int arm_v7s_unmap(struct io_pgtable_ops *ops, unsigned long iova,
+			 size_t size)
+{
+	size_t unmapped;
+	struct arm_v7s_io_pgtable *data = io_pgtable_ops_to_data(ops);
+	struct io_pgtable *iop = &data->iop;
+
+	unmapped = __arm_v7s_unmap(data, iova, size, 1, data->pgd);
+	if (unmapped)
+		iop->cfg.tlb->tlb_sync(iop->cookie);
+
+	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 {
+		pte = ptep[ARM_V7S_LVL_IDX(iova, ++lvl)];
+		ptep = iopte_deref(pte, lvl);
+	} 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 (pte & mask) | (iova & ~mask);
+}
+
+static struct io_pgtable *arm_v7s_alloc_pgtable(struct io_pgtable_cfg *cfg,
+						void *cookie)
+{
+	struct arm_v7s_io_pgtable *data;
+
+	if (cfg->ias > ARM_V7S_ADDR_BITS || cfg->oas > ARM_V7S_ADDR_BITS)
+		return NULL;
+
+	data = kmalloc(sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return NULL;
+
+	data->l2_tables = kmem_cache_create("io-pgtable_armv7s_l2",
+					    ARM_V7S_TABLE_SIZE(2),
+					    ARM_V7S_TABLE_SIZE(2),
+					    SLAB_CACHE_DMA, NULL);
+	if (!data->l2_tables)
+		goto out_free_data;
+
+	data->iop.ops = (struct io_pgtable_ops) {
+		.map		= arm_v7s_map,
+		.unmap		= arm_v7s_unmap,
+		.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, disable TTBR1 */
+	cfg->arm_v7s_cfg.tcr = ARM_V7S_TCR_PD1;
+
+	/*
+	 * 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();
+
+	/* TTBRs */
+	cfg->arm_v7s_cfg.ttbr[0] = virt_to_phys(data->pgd) |
+				   ARM_V7S_TTBR_S | ARM_V7S_TTBR_NOS |
+				   ARM_V7S_TTBR_IRGN_ATTR(ARM_V7S_RGN_WBWA) |
+				   ARM_V7S_TTBR_ORGN_ATTR(ARM_V7S_RGN_WBWA);
+	cfg->arm_v7s_cfg.ttbr[1] = 0;
+	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;
+
+static void dummy_tlb_flush_all(void *cookie)
+{
+	WARN_ON(cookie != cfg_cookie);
+}
+
+static void dummy_tlb_add_flush(unsigned long iova, size_t size,
+				size_t granule, bool leaf, void *cookie)
+{
+	WARN_ON(cookie != cfg_cookie);
+	WARN_ON(!(size & cfg_cookie->pgsize_bitmap));
+}
+
+static void dummy_tlb_sync(void *cookie)
+{
+	WARN_ON(cookie != cfg_cookie);
+}
+
+static struct iommu_gather_ops dummy_tlb_ops = {
+	.tlb_flush_all	= dummy_tlb_flush_all,
+	.tlb_add_flush	= dummy_tlb_add_flush,
+	.tlb_sync	= dummy_tlb_sync,
+};
+
+#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,
+		.quirks = IO_PGTABLE_QUIRK_ARM_NS,
+		.pgsize_bitmap = SZ_4K | SZ_64K | SZ_1M | SZ_16M,
+	};
+	unsigned int iova, size, iova_start;
+	unsigned int i, loopnr = 0;
+
+	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;
+	i = find_first_bit(&cfg.pgsize_bitmap, BITS_PER_LONG);
+	while (i != BITS_PER_LONG) {
+		size = 1UL << i;
+		if (ops->map(ops, iova, iova, size, IOMMU_READ |
+						    IOMMU_WRITE |
+						    IOMMU_NOEXEC |
+						    IOMMU_CACHE))
+			return __FAIL(ops);
+
+		/* Overlapping mappings */
+		if (!ops->map(ops, iova, iova + size, size,
+			      IOMMU_READ | IOMMU_NOEXEC))
+			return __FAIL(ops);
+
+		if (ops->iova_to_phys(ops, iova + 42) != (iova + 42))
+			return __FAIL(ops);
+
+		iova += SZ_16M;
+		i++;
+		i = find_next_bit(&cfg.pgsize_bitmap, BITS_PER_LONG, i);
+		loopnr++;
+	}
+
+	/* Partial unmap */
+	i = 1;
+	size = 1UL << __ffs(cfg.pgsize_bitmap);
+	while (i < loopnr) {
+		iova_start = i * SZ_16M;
+		if (ops->unmap(ops, iova_start + size, size) != size)
+			return __FAIL(ops);
+
+		/* Remap of partial unmap */
+		if (ops->map(ops, iova_start + size, size, size, IOMMU_READ))
+			return __FAIL(ops);
+
+		if (ops->iova_to_phys(ops, iova_start + size + 42)
+		    != (size + 42))
+			return __FAIL(ops);
+		i++;
+	}
+
+	/* Full unmap */
+	iova = 0;
+	i = find_first_bit(&cfg.pgsize_bitmap, BITS_PER_LONG);
+	while (i != BITS_PER_LONG) {
+		size = 1UL << i;
+
+		if (ops->unmap(ops, iova, size) != size)
+			return __FAIL(ops);
+
+		if (ops->iova_to_phys(ops, iova + 42))
+			return __FAIL(ops);
+
+		/* Remap full block */
+		if (ops->map(ops, iova, iova, size, IOMMU_WRITE))
+			return __FAIL(ops);
+
+		if (ops->iova_to_phys(ops, iova + 42) != (iova + 42))
+			return __FAIL(ops);
+
+		iova += SZ_16M;
+		i++;
+		i = find_next_bit(&cfg.pgsize_bitmap, BITS_PER_LONG, i);
+	}
+
+	free_io_pgtable_ops(ops);
+
+	selftest_running = false;
+
+	pr_info("self test ok\n");
+	return 0;
+}
+subsys_initcall(arm_v7s_do_selftests);
+#endif

drivers/iommu/io-pgtable.c

@@ -33,6 +33,9 @@ io_pgtable_init_table[IO_PGTABLE_NUM_FMTS] =
 	[ARM_64_LPAE_S1] = &io_pgtable_arm_64_lpae_s1_init_fns,
 	[ARM_64_LPAE_S2] = &io_pgtable_arm_64_lpae_s2_init_fns,
 #endif
+#ifdef CONFIG_IOMMU_IO_PGTABLE_ARMV7S
+	[ARM_V7S] = &io_pgtable_arm_v7s_init_fns,
+#endif
 };
 
 struct io_pgtable_ops *alloc_io_pgtable_ops(enum io_pgtable_fmt fmt,

drivers/iommu/io-pgtable.h

 #ifndef __IO_PGTABLE_H
 #define __IO_PGTABLE_H
+#include <linux/bitops.h>
 
 /*
  * Public API for use by IOMMU drivers
@@ -9,6 +10,7 @@ enum io_pgtable_fmt {
 	ARM_32_LPAE_S2,
 	ARM_64_LPAE_S1,
 	ARM_64_LPAE_S2,
+	ARM_V7S,
 	IO_PGTABLE_NUM_FMTS,
 };
 
@@ -45,7 +47,9 @@ struct iommu_gather_ops {
  *                 page table walker.
  */
 struct io_pgtable_cfg {
-	#define IO_PGTABLE_QUIRK_ARM_NS	(1 << 0)	/* Set NS bit in PTEs */
+	#define IO_PGTABLE_QUIRK_ARM_NS		BIT(0) /* Set NS bit in PTEs */
+	#define IO_PGTABLE_QUIRK_NO_PERMS	BIT(1) /* No AP/XN bits */
+	#define IO_PGTABLE_QUIRK_TLBI_ON_MAP	BIT(2) /* TLB Inv. on map */
 	int				quirks;
 	unsigned long			pgsize_bitmap;
 	unsigned int			ias;
@@ -65,6 +69,13 @@ struct io_pgtable_cfg {
 			u64	vttbr;
 			u64	vtcr;
 		} arm_lpae_s2_cfg;
+
+		struct {
+			u32	ttbr[2];
+			u32	tcr;
+			u32	nmrr;
+			u32	prrr;
+		} arm_v7s_cfg;
 	};
 };
 
@@ -149,5 +160,6 @@ extern struct io_pgtable_init_fns io_pgtable_arm_32_lpae_s1_init_fns;
 extern struct io_pgtable_init_fns io_pgtable_arm_32_lpae_s2_init_fns;
 extern struct io_pgtable_init_fns io_pgtable_arm_64_lpae_s1_init_fns;
 extern struct io_pgtable_init_fns io_pgtable_arm_64_lpae_s2_init_fns;
+extern struct io_pgtable_init_fns io_pgtable_arm_v7s_init_fns;
 
 #endif /* __IO_PGTABLE_H */