lib/iommu-common.c

   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/iommu-common.h>
  12 #include <linux/dma-mapping.h>
  13 #include <linux/hash.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 EXPORT_SYMBOL(iommu_tbl_pool_init);
  97
  98 unsigned long iommu_tbl_range_alloc(struct device *dev,
  99                                 struct iommu_map_table *iommu,
 100                                 unsigned long npages,
 101                                 unsigned long *handle,
 102                                 unsigned long mask,
 103                                 unsigned int align_order)
 104 {
 105         unsigned int pool_hash = __this_cpu_read(iommu_hash_common);
 106         unsigned long n, end, start, limit, boundary_size;
 107         struct iommu_pool *pool;
 108         int pass = 0;
 109         unsigned int pool_nr;
 110         unsigned int npools = iommu->nr_pools;
 111         unsigned long flags;
 112         bool large_pool = ((iommu->flags & IOMMU_HAS_LARGE_POOL) != 0);
 113         bool largealloc = (large_pool && npages > iommu_large_alloc);
 114         unsigned long shift;
 115         unsigned long align_mask = 0;
 116
 117         if (align_order > 0)
 118                 align_mask = ~0ul >> (BITS_PER_LONG - align_order);
 119
 120         /* Sanity check */
 121         if (unlikely(npages == 0)) {
 122                 WARN_ON_ONCE(1);
 123                 return IOMMU_ERROR_CODE;
 124         }
 125
 126         if (largealloc) {
 127                 pool = &(iommu->large_pool);
 128                 pool_nr = 0; /* to keep compiler happy */
 129         } else {
 130                 /* pick out pool_nr */
 131                 pool_nr =  pool_hash & (npools - 1);
 132                 pool = &(iommu->pools[pool_nr]);
 133         }
 134         spin_lock_irqsave(&pool->lock, flags);
 135
 136  again:
 137         if (pass == 0 && handle && *handle &&
 138             (*handle >= pool->start) && (*handle < pool->end))
 139                 start = *handle;
 140         else
 141                 start = pool->hint;
 142
 143         limit = pool->end;
 144
 145         /* The case below can happen if we have a small segment appended
 146          * to a large, or when the previous alloc was at the very end of
 147          * the available space. If so, go back to the beginning. If a
 148          * flush is needed, it will get done based on the return value
 149          * from iommu_area_alloc() below.
 150          */
 151         if (start >= limit)
 152                 start = pool->start;
 153         shift = iommu->table_map_base >> iommu->table_shift;
 154         if (limit + shift > mask) {
 155                 limit = mask - shift + 1;
 156                 /* If we're constrained on address range, first try
 157                  * at the masked hint to avoid O(n) search complexity,
 158                  * but on second pass, start at 0 in pool 0.
 159                  */
 160                 if ((start & mask) >= limit || pass > 0) {
 161                         spin_unlock(&(pool->lock));
 162                         pool = &(iommu->pools[0]);
 163                         spin_lock(&(pool->lock));
 164                         start = pool->start;
 165                 } else {
 166                         start &= mask;
 167                 }
 168         }
 169
 170         if (dev)
 171                 boundary_size = ALIGN(dma_get_seg_boundary(dev) + 1,
 172                                       1 << iommu->table_shift);
 173         else
 174                 boundary_size = ALIGN(1ULL << 32, 1 << iommu->table_shift);
 175
 176         boundary_size = boundary_size >> iommu->table_shift;
 177         /*
 178          * if the skip_span_boundary_check had been set during init, we set
 179          * things up so that iommu_is_span_boundary() merely checks if the
 180          * (index + npages) < num_tsb_entries
 181          */
 182         if ((iommu->flags & IOMMU_NO_SPAN_BOUND) != 0) {
 183                 shift = 0;
 184                 boundary_size = iommu->poolsize * iommu->nr_pools;
 185         }
 186         n = iommu_area_alloc(iommu->map, limit, start, npages, shift,
 187                              boundary_size, align_mask);
 188         if (n == -1) {
 189                 if (likely(pass == 0)) {
 190                         /* First failure, rescan from the beginning.  */
 191                         pool->hint = pool->start;
 192                         set_flush(iommu);
 193                         pass++;
 194                         goto again;
 195                 } else if (!largealloc && pass <= iommu->nr_pools) {
 196                         spin_unlock(&(pool->lock));
 197                         pool_nr = (pool_nr + 1) & (iommu->nr_pools - 1);
 198                         pool = &(iommu->pools[pool_nr]);
 199                         spin_lock(&(pool->lock));
 200                         pool->hint = pool->start;
 201                         set_flush(iommu);
 202                         pass++;
 203                         goto again;
 204                 } else {
 205                         /* give up */
 206                         n = IOMMU_ERROR_CODE;
 207                         goto bail;
 208                 }
 209         }
 210         if (iommu->lazy_flush &&
 211             (n < pool->hint || need_flush(iommu))) {
 212                 clear_flush(iommu);
 213                 iommu->lazy_flush(iommu);
 214         }
 215
 216         end = n + npages;
 217         pool->hint = end;
 218
 219         /* Update handle for SG allocations */
 220         if (handle)
 221                 *handle = end;
 222 bail:
 223         spin_unlock_irqrestore(&(pool->lock), flags);
 224
 225         return n;
 226 }
 227 EXPORT_SYMBOL(iommu_tbl_range_alloc);
 228
 229 static struct iommu_pool *get_pool(struct iommu_map_table *tbl,
 230                                    unsigned long entry)
 231 {
 232         struct iommu_pool *p;
 233         unsigned long largepool_start = tbl->large_pool.start;
 234         bool large_pool = ((tbl->flags & IOMMU_HAS_LARGE_POOL) != 0);
 235
 236         /* The large pool is the last pool at the top of the table */
 237         if (large_pool && entry >= largepool_start) {
 238                 p = &tbl->large_pool;
 239         } else {
 240                 unsigned int pool_nr = entry / tbl->poolsize;
 241
 242                 BUG_ON(pool_nr >= tbl->nr_pools);
 243                 p = &tbl->pools[pool_nr];
 244         }
 245         return p;
 246 }
 247
 248 /* Caller supplies the index of the entry into the iommu map table
 249  * itself when the mapping from dma_addr to the entry is not the
 250  * default addr->entry mapping below.
 251  */
 252 void iommu_tbl_range_free(struct iommu_map_table *iommu, u64 dma_addr,
 253                           unsigned long npages, unsigned long entry)
 254 {
 255         struct iommu_pool *pool;
 256         unsigned long flags;
 257         unsigned long shift = iommu->table_shift;
 258
 259         if (entry == IOMMU_ERROR_CODE) /* use default addr->entry mapping */
 260                 entry = (dma_addr - iommu->table_map_base) >> shift;
 261         pool = get_pool(iommu, entry);
 262
 263         spin_lock_irqsave(&(pool->lock), flags);
 264         bitmap_clear(iommu->map, entry, npages);
 265         spin_unlock_irqrestore(&(pool->lock), flags);
 266 }
 267 EXPORT_SYMBOL(iommu_tbl_range_free);