diff options
Diffstat (limited to 'drivers/iommu/io-pgtable-dart.c')
| -rw-r--r-- | drivers/iommu/io-pgtable-dart.c | 483 |
1 files changed, 483 insertions, 0 deletions
diff --git a/drivers/iommu/io-pgtable-dart.c b/drivers/iommu/io-pgtable-dart.c new file mode 100644 index 000000000000..54d287cc0dd1 --- /dev/null +++ b/drivers/iommu/io-pgtable-dart.c @@ -0,0 +1,483 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Apple DART page table allocator. + * + * Copyright (C) 2022 The Asahi Linux Contributors + * + * Based on io-pgtable-arm. + * + * Copyright (C) 2014 ARM Limited + * + * Author: Will Deacon <will.deacon@arm.com> + */ + +#define pr_fmt(fmt) "dart io-pgtable: " fmt + +#include <linux/atomic.h> +#include <linux/bitfield.h> +#include <linux/bitops.h> +#include <linux/io-pgtable.h> +#include <linux/kernel.h> +#include <linux/sizes.h> +#include <linux/slab.h> +#include <linux/types.h> + +#include <asm/barrier.h> +#include "iommu-pages.h" + +#define DART1_MAX_ADDR_BITS 36 + +#define DART_MAX_TABLE_BITS 2 +#define DART_MAX_TABLES BIT(DART_MAX_TABLE_BITS) +#define DART_MAX_LEVELS 4 /* Includes TTBR level */ + +/* Struct accessors */ +#define io_pgtable_to_data(x) \ + container_of((x), struct dart_io_pgtable, iop) + +#define io_pgtable_ops_to_data(x) \ + io_pgtable_to_data(io_pgtable_ops_to_pgtable(x)) + +#define DART_GRANULE(d) \ + (sizeof(dart_iopte) << (d)->bits_per_level) +#define DART_PTES_PER_TABLE(d) \ + (DART_GRANULE(d) >> ilog2(sizeof(dart_iopte))) + +#define APPLE_DART_PTE_SUBPAGE_START GENMASK_ULL(63, 52) +#define APPLE_DART_PTE_SUBPAGE_END GENMASK_ULL(51, 40) + +#define APPLE_DART1_PADDR_MASK GENMASK_ULL(35, 12) +#define APPLE_DART2_PADDR_MASK GENMASK_ULL(37, 10) +#define APPLE_DART2_PADDR_SHIFT (4) + +/* Apple DART1 protection bits */ +#define APPLE_DART1_PTE_PROT_NO_READ BIT(8) +#define APPLE_DART1_PTE_PROT_NO_WRITE BIT(7) +#define APPLE_DART1_PTE_PROT_SP_DIS BIT(1) + +/* Apple DART2 protection bits */ +#define APPLE_DART2_PTE_PROT_NO_READ BIT(3) +#define APPLE_DART2_PTE_PROT_NO_WRITE BIT(2) +#define APPLE_DART2_PTE_PROT_NO_CACHE BIT(1) + +/* marks PTE as valid */ +#define APPLE_DART_PTE_VALID BIT(0) + +/* IOPTE accessors */ +#define iopte_deref(pte, d) __va(iopte_to_paddr(pte, d)) + +struct dart_io_pgtable { + struct io_pgtable iop; + + int levels; + int tbl_bits; + int bits_per_level; + + void *pgd[DART_MAX_TABLES]; +}; + +typedef u64 dart_iopte; + + +static dart_iopte paddr_to_iopte(phys_addr_t paddr, + struct dart_io_pgtable *data) +{ + dart_iopte pte; + + if (data->iop.fmt == APPLE_DART) + return paddr & APPLE_DART1_PADDR_MASK; + + /* format is APPLE_DART2 */ + pte = paddr >> APPLE_DART2_PADDR_SHIFT; + pte &= APPLE_DART2_PADDR_MASK; + + return pte; +} + +static phys_addr_t iopte_to_paddr(dart_iopte pte, + struct dart_io_pgtable *data) +{ + u64 paddr; + + if (data->iop.fmt == APPLE_DART) + return pte & APPLE_DART1_PADDR_MASK; + + /* format is APPLE_DART2 */ + paddr = pte & APPLE_DART2_PADDR_MASK; + paddr <<= APPLE_DART2_PADDR_SHIFT; + + return paddr; +} + +static int dart_init_pte(struct dart_io_pgtable *data, + unsigned long iova, phys_addr_t paddr, + dart_iopte prot, int num_entries, + dart_iopte *ptep) +{ + int i; + dart_iopte pte = prot; + size_t sz = data->iop.cfg.pgsize_bitmap; + + for (i = 0; i < num_entries; i++) + if (ptep[i] & APPLE_DART_PTE_VALID) { + /* We require an unmap first */ + WARN_ON(ptep[i] & APPLE_DART_PTE_VALID); + return -EEXIST; + } + + /* subpage protection: always allow access to the entire page */ + pte |= FIELD_PREP(APPLE_DART_PTE_SUBPAGE_START, 0); + pte |= FIELD_PREP(APPLE_DART_PTE_SUBPAGE_END, 0xfff); + + pte |= APPLE_DART_PTE_VALID; + + for (i = 0; i < num_entries; i++) + ptep[i] = pte | paddr_to_iopte(paddr + i * sz, data); + + return 0; +} + +static dart_iopte dart_install_table(dart_iopte *table, + dart_iopte *ptep, + dart_iopte curr, + struct dart_io_pgtable *data) +{ + dart_iopte old, new; + + new = paddr_to_iopte(__pa(table), data) | APPLE_DART_PTE_VALID; + + /* + * 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 = cmpxchg64_relaxed(ptep, curr, new); + + return old; +} + +static int dart_get_index(struct dart_io_pgtable *data, unsigned long iova, int level) +{ + return (iova >> (level * data->bits_per_level + ilog2(sizeof(dart_iopte)))) & + ((1 << data->bits_per_level) - 1); +} + +static int dart_get_last_index(struct dart_io_pgtable *data, unsigned long iova) +{ + + return (iova >> (data->bits_per_level + ilog2(sizeof(dart_iopte)))) & + ((1 << data->bits_per_level) - 1); +} + +static dart_iopte *dart_get_last(struct dart_io_pgtable *data, unsigned long iova) +{ + dart_iopte pte, *ptep; + int level = data->levels; + int tbl = dart_get_index(data, iova, level); + + if (tbl >= (1 << data->tbl_bits)) + return NULL; + + ptep = data->pgd[tbl]; + if (!ptep) + return NULL; + + while (--level > 1) { + ptep += dart_get_index(data, iova, level); + pte = READ_ONCE(*ptep); + + /* Valid entry? */ + if (!pte) + return NULL; + + /* Deref to get next level table */ + ptep = iopte_deref(pte, data); + } + + return ptep; +} + +static dart_iopte dart_prot_to_pte(struct dart_io_pgtable *data, + int prot) +{ + dart_iopte pte = 0; + + if (data->iop.fmt == APPLE_DART) { + pte |= APPLE_DART1_PTE_PROT_SP_DIS; + if (!(prot & IOMMU_WRITE)) + pte |= APPLE_DART1_PTE_PROT_NO_WRITE; + if (!(prot & IOMMU_READ)) + pte |= APPLE_DART1_PTE_PROT_NO_READ; + } + if (data->iop.fmt == APPLE_DART2) { + if (!(prot & IOMMU_WRITE)) + pte |= APPLE_DART2_PTE_PROT_NO_WRITE; + if (!(prot & IOMMU_READ)) + pte |= APPLE_DART2_PTE_PROT_NO_READ; + if (!(prot & IOMMU_CACHE)) + pte |= APPLE_DART2_PTE_PROT_NO_CACHE; + } + + return pte; +} + +static int dart_map_pages(struct io_pgtable_ops *ops, unsigned long iova, + phys_addr_t paddr, size_t pgsize, size_t pgcount, + int iommu_prot, gfp_t gfp, size_t *mapped) +{ + struct dart_io_pgtable *data = io_pgtable_ops_to_data(ops); + struct io_pgtable_cfg *cfg = &data->iop.cfg; + size_t tblsz = DART_GRANULE(data); + int ret = 0, tbl, num_entries, max_entries, map_idx_start; + dart_iopte pte, *cptep, *ptep; + dart_iopte prot; + int level = data->levels; + + if (WARN_ON(pgsize != cfg->pgsize_bitmap)) + return -EINVAL; + + if (WARN_ON(paddr >> cfg->oas)) + return -ERANGE; + + if (!(iommu_prot & (IOMMU_READ | IOMMU_WRITE))) + return -EINVAL; + + tbl = dart_get_index(data, iova, level); + + if (tbl >= (1 << data->tbl_bits)) + return -ENOMEM; + + ptep = data->pgd[tbl]; + while (--level > 1) { + ptep += dart_get_index(data, iova, level); + pte = READ_ONCE(*ptep); + + /* no table present */ + if (!pte) { + cptep = iommu_alloc_pages_sz(gfp, tblsz); + if (!cptep) + return -ENOMEM; + + pte = dart_install_table(cptep, ptep, 0, data); + if (pte) + iommu_free_pages(cptep); + + /* L2 table is present (now) */ + pte = READ_ONCE(*ptep); + } + + ptep = iopte_deref(pte, data); + } + + /* install a leaf entries into L2 table */ + prot = dart_prot_to_pte(data, iommu_prot); + map_idx_start = dart_get_last_index(data, iova); + max_entries = DART_PTES_PER_TABLE(data) - map_idx_start; + num_entries = min_t(int, pgcount, max_entries); + ptep += map_idx_start; + ret = dart_init_pte(data, iova, paddr, prot, num_entries, ptep); + if (!ret && mapped) + *mapped += num_entries * 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 size_t dart_unmap_pages(struct io_pgtable_ops *ops, unsigned long iova, + size_t pgsize, size_t pgcount, + struct iommu_iotlb_gather *gather) +{ + struct dart_io_pgtable *data = io_pgtable_ops_to_data(ops); + struct io_pgtable_cfg *cfg = &data->iop.cfg; + int i = 0, num_entries, max_entries, unmap_idx_start; + dart_iopte pte, *ptep; + + if (WARN_ON(pgsize != cfg->pgsize_bitmap || !pgcount)) + return 0; + + ptep = dart_get_last(data, iova); + + /* Valid L2 IOPTE pointer? */ + if (WARN_ON(!ptep)) + return 0; + + unmap_idx_start = dart_get_last_index(data, iova); + ptep += unmap_idx_start; + + max_entries = DART_PTES_PER_TABLE(data) - unmap_idx_start; + num_entries = min_t(int, pgcount, max_entries); + + while (i < num_entries) { + pte = READ_ONCE(*ptep); + if (WARN_ON(!pte)) + break; + + /* clear pte */ + *ptep = 0; + + if (!iommu_iotlb_gather_queued(gather)) + io_pgtable_tlb_add_page(&data->iop, gather, + iova + i * pgsize, pgsize); + + ptep++; + i++; + } + + return i * pgsize; +} + +static phys_addr_t dart_iova_to_phys(struct io_pgtable_ops *ops, + unsigned long iova) +{ + struct dart_io_pgtable *data = io_pgtable_ops_to_data(ops); + dart_iopte pte, *ptep; + + ptep = dart_get_last(data, iova); + + /* Valid L2 IOPTE pointer? */ + if (!ptep) + return 0; + + ptep += dart_get_last_index(data, iova); + + pte = READ_ONCE(*ptep); + /* Found translation */ + if (pte) { + iova &= (data->iop.cfg.pgsize_bitmap - 1); + return iopte_to_paddr(pte, data) | iova; + } + + /* Ran out of page tables to walk */ + return 0; +} + +static struct dart_io_pgtable * +dart_alloc_pgtable(struct io_pgtable_cfg *cfg) +{ + struct dart_io_pgtable *data; + int levels, max_tbl_bits, tbl_bits, bits_per_level, va_bits, pg_shift; + + /* + * Old 4K page DARTs can use up to 4 top-level tables. + * Newer ones only ever use a maximum of 1. + */ + if (cfg->pgsize_bitmap == SZ_4K) + max_tbl_bits = DART_MAX_TABLE_BITS; + else + max_tbl_bits = 0; + + pg_shift = __ffs(cfg->pgsize_bitmap); + bits_per_level = pg_shift - ilog2(sizeof(dart_iopte)); + + va_bits = cfg->ias - pg_shift; + + levels = max_t(int, 2, (va_bits - max_tbl_bits + bits_per_level - 1) / bits_per_level); + + if (levels > (DART_MAX_LEVELS - 1)) + return NULL; + + tbl_bits = max_t(int, 0, va_bits - (bits_per_level * levels)); + + if (tbl_bits > max_tbl_bits) + return NULL; + + data = kzalloc(sizeof(*data), GFP_KERNEL); + if (!data) + return NULL; + + data->levels = levels + 1; /* Table level counts as one level */ + data->tbl_bits = tbl_bits; + data->bits_per_level = bits_per_level; + + data->iop.ops = (struct io_pgtable_ops) { + .map_pages = dart_map_pages, + .unmap_pages = dart_unmap_pages, + .iova_to_phys = dart_iova_to_phys, + }; + + return data; +} + +static struct io_pgtable * +apple_dart_alloc_pgtable(struct io_pgtable_cfg *cfg, void *cookie) +{ + struct dart_io_pgtable *data; + int i; + + if (!cfg->coherent_walk) + return NULL; + + if (cfg->oas != 36 && cfg->oas != 42) + return NULL; + + if (cfg->ias > cfg->oas) + return NULL; + + if (!(cfg->pgsize_bitmap == SZ_4K || cfg->pgsize_bitmap == SZ_16K)) + return NULL; + + data = dart_alloc_pgtable(cfg); + if (!data) + return NULL; + + cfg->apple_dart_cfg.n_ttbrs = 1 << data->tbl_bits; + cfg->apple_dart_cfg.n_levels = data->levels; + + for (i = 0; i < cfg->apple_dart_cfg.n_ttbrs; ++i) { + data->pgd[i] = + iommu_alloc_pages_sz(GFP_KERNEL, DART_GRANULE(data)); + if (!data->pgd[i]) + goto out_free_data; + cfg->apple_dart_cfg.ttbr[i] = virt_to_phys(data->pgd[i]); + } + + return &data->iop; + +out_free_data: + while (--i >= 0) { + iommu_free_pages(data->pgd[i]); + } + kfree(data); + return NULL; +} + +static void apple_dart_free_pgtables(struct dart_io_pgtable *data, dart_iopte *ptep, int level) +{ + dart_iopte *end; + dart_iopte *start = ptep; + + if (level > 1) { + end = (void *)ptep + DART_GRANULE(data); + + while (ptep != end) { + dart_iopte pte = *ptep++; + + if (pte) + apple_dart_free_pgtables(data, iopte_deref(pte, data), level - 1); + } + } + iommu_free_pages(start); +} + +static void apple_dart_free_pgtable(struct io_pgtable *iop) +{ + struct dart_io_pgtable *data = io_pgtable_to_data(iop); + int i; + + for (i = 0; i < (1 << data->tbl_bits) && data->pgd[i]; ++i) + apple_dart_free_pgtables(data, data->pgd[i], data->levels - 1); + + kfree(data); +} + +struct io_pgtable_init_fns io_pgtable_apple_dart_init_fns = { + .alloc = apple_dart_alloc_pgtable, + .free = apple_dart_free_pgtable, +}; |