1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * IOMMU mmap management and range allocation functions. 4 * Based almost entirely upon the powerpc iommu allocator. 5 */ 6 7 #include <linux/export.h> 8 #include <linux/bitmap.h> 9 #include <linux/bug.h> 10 #include <linux/iommu-helper.h> 11 #include <linux/dma-mapping.h> 12 #include <linux/hash.h> 13 #include <asm/iommu-common.h> 14 15 static unsigned long iommu_large_alloc = 15; 16 17 static DEFINE_PER_CPU(unsigned int, iommu_hash_common); 18 19 static inline bool need_flush(struct iommu_map_table *iommu) 20 { 21 return ((iommu->flags & IOMMU_NEED_FLUSH) != 0); 22 } 23 24 static inline void set_flush(struct iommu_map_table *iommu) 25 { 26 iommu->flags |= IOMMU_NEED_FLUSH; 27 } 28 29 static inline void clear_flush(struct iommu_map_table *iommu) 30 { 31 iommu->flags &= ~IOMMU_NEED_FLUSH; 32 } 33 34 static void setup_iommu_pool_hash(void) 35 { 36 unsigned int i; 37 static bool do_once; 38 39 if (do_once) 40 return; 41 do_once = true; 42 for_each_possible_cpu(i) 43 per_cpu(iommu_hash_common, i) = hash_32(i, IOMMU_POOL_HASHBITS); 44 } 45 46 /* 47 * Initialize iommu_pool entries for the iommu_map_table. `num_entries' 48 * is the number of table entries. If `large_pool' is set to true, 49 * the top 1/4 of the table will be set aside for pool allocations 50 * of more than iommu_large_alloc pages. 51 */ 52 void iommu_tbl_pool_init(struct iommu_map_table *iommu, 53 unsigned long num_entries, 54 u32 table_shift, 55 void (*lazy_flush)(struct iommu_map_table *), 56 bool large_pool, u32 npools, 57 bool skip_span_boundary_check) 58 { 59 unsigned int start, i; 60 struct iommu_pool *p = &(iommu->large_pool); 61 62 setup_iommu_pool_hash(); 63 if (npools == 0) 64 iommu->nr_pools = IOMMU_NR_POOLS; 65 else 66 iommu->nr_pools = npools; 67 BUG_ON(npools > IOMMU_NR_POOLS); 68 69 iommu->table_shift = table_shift; 70 iommu->lazy_flush = lazy_flush; 71 start = 0; 72 if (skip_span_boundary_check) 73 iommu->flags |= IOMMU_NO_SPAN_BOUND; 74 if (large_pool) 75 iommu->flags |= IOMMU_HAS_LARGE_POOL; 76 77 if (!large_pool) 78 iommu->poolsize = num_entries/iommu->nr_pools; 79 else 80 iommu->poolsize = (num_entries * 3 / 4)/iommu->nr_pools; 81 for (i = 0; i < iommu->nr_pools; i++) { 82 spin_lock_init(&(iommu->pools[i].lock)); 83 iommu->pools[i].start = start; 84 iommu->pools[i].hint = start; 85 start += iommu->poolsize; /* start for next pool */ 86 iommu->pools[i].end = start - 1; 87 } 88 if (!large_pool) 89 return; 90 /* initialize large_pool */ 91 spin_lock_init(&(p->lock)); 92 p->start = start; 93 p->hint = p->start; 94 p->end = num_entries; 95 } 96 97 unsigned long iommu_tbl_range_alloc(struct device *dev, 98 struct iommu_map_table *iommu, 99 unsigned long npages, 100 unsigned long *handle, 101 unsigned long mask, 102 unsigned int align_order) 103 { 104 unsigned int pool_hash = __this_cpu_read(iommu_hash_common); 105 unsigned long n, end, start, limit, boundary_size; 106 struct iommu_pool *pool; 107 int pass = 0; 108 unsigned int pool_nr; 109 unsigned int npools = iommu->nr_pools; 110 unsigned long flags; 111 bool large_pool = ((iommu->flags & IOMMU_HAS_LARGE_POOL) != 0); 112 bool largealloc = (large_pool && npages > iommu_large_alloc); 113 unsigned long shift; 114 unsigned long align_mask = 0; 115 116 if (align_order > 0) 117 align_mask = ~0ul >> (BITS_PER_LONG - align_order); 118 119 /* Sanity check */ 120 if (unlikely(npages == 0)) { 121 WARN_ON_ONCE(1); 122 return IOMMU_ERROR_CODE; 123 } 124 125 if (largealloc) { 126 pool = &(iommu->large_pool); 127 pool_nr = 0; /* to keep compiler happy */ 128 } else { 129 /* pick out pool_nr */ 130 pool_nr = pool_hash & (npools - 1); 131 pool = &(iommu->pools[pool_nr]); 132 } 133 spin_lock_irqsave(&pool->lock, flags); 134 135 again: 136 if (pass == 0 && handle && *handle && 137 (*handle >= pool->start) && (*handle < pool->end)) 138 start = *handle; 139 else 140 start = pool->hint; 141 142 limit = pool->end; 143 144 /* The case below can happen if we have a small segment appended 145 * to a large, or when the previous alloc was at the very end of 146 * the available space. If so, go back to the beginning. If a 147 * flush is needed, it will get done based on the return value 148 * from iommu_area_alloc() below. 149 */ 150 if (start >= limit) 151 start = pool->start; 152 shift = iommu->table_map_base >> iommu->table_shift; 153 if (limit + shift > mask) { 154 limit = mask - shift + 1; 155 /* If we're constrained on address range, first try 156 * at the masked hint to avoid O(n) search complexity, 157 * but on second pass, start at 0 in pool 0. 158 */ 159 if ((start & mask) >= limit || pass > 0) { 160 spin_unlock(&(pool->lock)); 161 pool = &(iommu->pools[0]); 162 spin_lock(&(pool->lock)); 163 start = pool->start; 164 } else { 165 start &= mask; 166 } 167 } 168 169 /* 170 * if the skip_span_boundary_check had been set during init, we set 171 * things up so that iommu_is_span_boundary() merely checks if the 172 * (index + npages) < num_tsb_entries 173 */ 174 if ((iommu->flags & IOMMU_NO_SPAN_BOUND) != 0) { 175 shift = 0; 176 boundary_size = iommu->poolsize * iommu->nr_pools; 177 } else { 178 boundary_size = dma_get_seg_boundary_nr_pages(dev, 179 iommu->table_shift); 180 } 181 n = iommu_area_alloc(iommu->map, limit, start, npages, shift, 182 boundary_size, align_mask); 183 if (n == -1) { 184 if (likely(pass == 0)) { 185 /* First failure, rescan from the beginning. */ 186 pool->hint = pool->start; 187 set_flush(iommu); 188 pass++; 189 goto again; 190 } else if (!largealloc && pass <= iommu->nr_pools) { 191 spin_unlock(&(pool->lock)); 192 pool_nr = (pool_nr + 1) & (iommu->nr_pools - 1); 193 pool = &(iommu->pools[pool_nr]); 194 spin_lock(&(pool->lock)); 195 pool->hint = pool->start; 196 set_flush(iommu); 197 pass++; 198 goto again; 199 } else { 200 /* give up */ 201 n = IOMMU_ERROR_CODE; 202 goto bail; 203 } 204 } 205 if (iommu->lazy_flush && 206 (n < pool->hint || need_flush(iommu))) { 207 clear_flush(iommu); 208 iommu->lazy_flush(iommu); 209 } 210 211 end = n + npages; 212 pool->hint = end; 213 214 /* Update handle for SG allocations */ 215 if (handle) 216 *handle = end; 217 bail: 218 spin_unlock_irqrestore(&(pool->lock), flags); 219 220 return n; 221 } 222 223 static struct iommu_pool *get_pool(struct iommu_map_table *tbl, 224 unsigned long entry) 225 { 226 struct iommu_pool *p; 227 unsigned long largepool_start = tbl->large_pool.start; 228 bool large_pool = ((tbl->flags & IOMMU_HAS_LARGE_POOL) != 0); 229 230 /* The large pool is the last pool at the top of the table */ 231 if (large_pool && entry >= largepool_start) { 232 p = &tbl->large_pool; 233 } else { 234 unsigned int pool_nr = entry / tbl->poolsize; 235 236 BUG_ON(pool_nr >= tbl->nr_pools); 237 p = &tbl->pools[pool_nr]; 238 } 239 return p; 240 } 241 242 /* Caller supplies the index of the entry into the iommu map table 243 * itself when the mapping from dma_addr to the entry is not the 244 * default addr->entry mapping below. 245 */ 246 void iommu_tbl_range_free(struct iommu_map_table *iommu, u64 dma_addr, 247 unsigned long npages, unsigned long entry) 248 { 249 struct iommu_pool *pool; 250 unsigned long flags; 251 unsigned long shift = iommu->table_shift; 252 253 if (entry == IOMMU_ERROR_CODE) /* use default addr->entry mapping */ 254 entry = (dma_addr - iommu->table_map_base) >> shift; 255 pool = get_pool(iommu, entry); 256 257 spin_lock_irqsave(&(pool->lock), flags); 258 bitmap_clear(iommu->map, entry, npages); 259 spin_unlock_irqrestore(&(pool->lock), flags); 260 } 261