lib/iommu-common.c

   1 /*
   2  * IOMMU mmap management and range allocation functions.
   3  * Based almost entirely upon the powerpc iommu allocator.
   4  */
   5
   6 #include <linux/export.h>
   7 #include <linux/bitmap.h>
   8 #include <linux/bug.h>
   9 #include <linux/iommu-helper.h>
  10 #include <linux/iommu-common.h>
  11 #include <linux/dma-mapping.h>
  12 #include <linux/hash.h>
  13
  14 #ifndef DMA_ERROR_CODE
  15 #define DMA_ERROR_CODE (~(dma_addr_t)0x0)
  16 #endif
  17
  18 static unsigned long iommu_large_alloc = 15;
  19
  20 static  DEFINE_PER_CPU(unsigned int, iommu_hash_common);
  21
  22 static inline bool need_flush(struct iommu_map_table *iommu)
  23 {
  24         return (iommu->lazy_flush != NULL &&
  25                 (iommu->flags & IOMMU_NEED_FLUSH) != 0);
  26 }
  27
  28 static inline void set_flush(struct iommu_map_table *iommu)
  29 {
  30         iommu->flags |= IOMMU_NEED_FLUSH;
  31 }
  32
  33 static inline void clear_flush(struct iommu_map_table *iommu)
  34 {
  35         iommu->flags &= ~IOMMU_NEED_FLUSH;
  36 }
  37
  38 static void setup_iommu_pool_hash(void)
  39 {
  40         unsigned int i;
  41         static bool do_once;
  42
  43         if (do_once)
  44                 return;
  45         do_once = true;
  46         for_each_possible_cpu(i)
  47                 per_cpu(iommu_hash_common, i) = hash_32(i, IOMMU_POOL_HASHBITS);
  48 }
  49
  50 /*
  51  * Initialize iommu_pool entries for the iommu_map_table. `num_entries'
  52  * is the number of table entries. If `large_pool' is set to true,
  53  * the top 1/4 of the table will be set aside for pool allocations
  54  * of more than iommu_large_alloc pages.
  55  */
  56 void iommu_tbl_pool_init(struct iommu_map_table *iommu,
  57                          unsigned long num_entries,
  58                          u32 table_shift,
  59                          void (*lazy_flush)(struct iommu_map_table *),
  60                          bool large_pool, u32 npools,
  61                          bool skip_span_boundary_check)
  62 {
  63         unsigned int start, i;
  64         struct iommu_pool *p = &(iommu->large_pool);
  65
  66         setup_iommu_pool_hash();
  67         if (npools == 0)
  68                 iommu->nr_pools = IOMMU_NR_POOLS;
  69         else
  70                 iommu->nr_pools = npools;
  71         BUG_ON(npools > IOMMU_NR_POOLS);
  72
  73         iommu->table_shift = table_shift;
  74         iommu->lazy_flush = lazy_flush;
  75         start = 0;
  76         if (skip_span_boundary_check)
  77                 iommu->flags |= IOMMU_NO_SPAN_BOUND;
  78         if (large_pool)
  79                 iommu->flags |= IOMMU_HAS_LARGE_POOL;
  80
  81         if (!large_pool)
  82                 iommu->poolsize = num_entries/iommu->nr_pools;
  83         else
  84                 iommu->poolsize = (num_entries * 3 / 4)/iommu->nr_pools;
  85         for (i = 0; i < iommu->nr_pools; i++) {
  86                 spin_lock_init(&(iommu->pools[i].lock));
  87                 iommu->pools[i].start = start;
  88                 iommu->pools[i].hint = start;
  89                 start += iommu->poolsize; /* start for next pool */
  90                 iommu->pools[i].end = start - 1;
  91         }
  92         if (!large_pool)
  93                 return;
  94         /* initialize large_pool */
  95         spin_lock_init(&(p->lock));
  96         p->start = start;
  97         p->hint = p->start;
  98         p->end = num_entries;
  99 }
 100 EXPORT_SYMBOL(iommu_tbl_pool_init);
 101
 102 unsigned long iommu_tbl_range_alloc(struct device *dev,
 103                                 struct iommu_map_table *iommu,
 104                                 unsigned long npages,
 105                                 unsigned long *handle,
 106                                 unsigned long mask,
 107                                 unsigned int align_order)
 108 {
 109         unsigned int pool_hash = __this_cpu_read(iommu_hash_common);
 110         unsigned long n, end, start, limit, boundary_size;
 111         struct iommu_pool *pool;
 112         int pass = 0;
 113         unsigned int pool_nr;
 114         unsigned int npools = iommu->nr_pools;
 115         unsigned long flags;
 116         bool large_pool = ((iommu->flags & IOMMU_HAS_LARGE_POOL) != 0);
 117         bool largealloc = (large_pool && npages > iommu_large_alloc);
 118         unsigned long shift;
 119         unsigned long align_mask = 0;
 120
 121         if (align_order > 0)
 122                 align_mask = ~0ul >> (BITS_PER_LONG - align_order);
 123
 124         /* Sanity check */
 125         if (unlikely(npages == 0)) {
 126                 WARN_ON_ONCE(1);
 127                 return DMA_ERROR_CODE;
 128         }
 129
 130         if (largealloc) {
 131                 pool = &(iommu->large_pool);
 132                 pool_nr = 0; /* to keep compiler happy */
 133         } else {
 134                 /* pick out pool_nr */
 135                 pool_nr =  pool_hash & (npools - 1);
 136                 pool = &(iommu->pools[pool_nr]);
 137         }
 138         spin_lock_irqsave(&pool->lock, flags);
 139
 140  again:
 141         if (pass == 0 && handle && *handle &&
 142             (*handle >= pool->start) && (*handle < pool->end))
 143                 start = *handle;
 144         else
 145                 start = pool->hint;
 146
 147         limit = pool->end;
 148
 149         /* The case below can happen if we have a small segment appended
 150          * to a large, or when the previous alloc was at the very end of
 151          * the available space. If so, go back to the beginning. If a
 152          * flush is needed, it will get done based on the return value
 153          * from iommu_area_alloc() below.
 154          */
 155         if (start >= limit)
 156                 start = pool->start;
 157         shift = iommu->table_map_base >> iommu->table_shift;
 158         if (limit + shift > mask) {
 159                 limit = mask - shift + 1;
 160                 /* If we're constrained on address range, first try
 161                  * at the masked hint to avoid O(n) search complexity,
 162                  * but on second pass, start at 0 in pool 0.
 163                  */
 164                 if ((start & mask) >= limit || pass > 0) {
 165                         spin_unlock(&(pool->lock));
 166                         pool = &(iommu->pools[0]);
 167                         spin_lock(&(pool->lock));
 168                         start = pool->start;
 169                 } else {
 170                         start &= mask;
 171                 }
 172         }
 173
 174         if (dev)
 175                 boundary_size = ALIGN(dma_get_seg_boundary(dev) + 1,
 176                                       1 << iommu->table_shift);
 177         else
 178                 boundary_size = ALIGN(1ULL << 32, 1 << iommu->table_shift);
 179
 180         boundary_size = boundary_size >> iommu->table_shift;
 181         /*
 182          * if the skip_span_boundary_check had been set during init, we set
 183          * things up so that iommu_is_span_boundary() merely checks if the
 184          * (index + npages) < num_tsb_entries
 185          */
 186         if ((iommu->flags & IOMMU_NO_SPAN_BOUND) != 0) {
 187                 shift = 0;
 188                 boundary_size = iommu->poolsize * iommu->nr_pools;
 189         }
 190         n = iommu_area_alloc(iommu->map, limit, start, npages, shift,
 191                              boundary_size, align_mask);
 192         if (n == -1) {
 193                 if (likely(pass == 0)) {
 194                         /* First failure, rescan from the beginning.  */
 195                         pool->hint = pool->start;
 196                         set_flush(iommu);
 197                         pass++;
 198                         goto again;
 199                 } else if (!largealloc && pass <= iommu->nr_pools) {
 200                         spin_unlock(&(pool->lock));
 201                         pool_nr = (pool_nr + 1) & (iommu->nr_pools - 1);
 202                         pool = &(iommu->pools[pool_nr]);
 203                         spin_lock(&(pool->lock));
 204                         pool->hint = pool->start;
 205                         set_flush(iommu);
 206                         pass++;
 207                         goto again;
 208                 } else {
 209                         /* give up */
 210                         n = DMA_ERROR_CODE;
 211                         goto bail;
 212                 }
 213         }
 214         if (n < pool->hint || need_flush(iommu)) {
 215                 clear_flush(iommu);
 216                 iommu->lazy_flush(iommu);
 217         }
 218
 219         end = n + npages;
 220         pool->hint = end;
 221
 222         /* Update handle for SG allocations */
 223         if (handle)
 224                 *handle = end;
 225 bail:
 226         spin_unlock_irqrestore(&(pool->lock), flags);
 227
 228         return n;
 229 }
 230 EXPORT_SYMBOL(iommu_tbl_range_alloc);
 231
 232 static struct iommu_pool *get_pool(struct iommu_map_table *tbl,
 233                                    unsigned long entry)
 234 {
 235         struct iommu_pool *p;
 236         unsigned long largepool_start = tbl->large_pool.start;
 237         bool large_pool = ((tbl->flags & IOMMU_HAS_LARGE_POOL) != 0);
 238
 239         /* The large pool is the last pool at the top of the table */
 240         if (large_pool && entry >= largepool_start) {
 241                 p = &tbl->large_pool;
 242         } else {
 243                 unsigned int pool_nr = entry / tbl->poolsize;
 244
 245                 BUG_ON(pool_nr >= tbl->nr_pools);
 246                 p = &tbl->pools[pool_nr];
 247         }
 248         return p;
 249 }
 250
 251 /* Caller supplies the index of the entry into the iommu map table
 252  * itself when the mapping from dma_addr to the entry is not the
 253  * default addr->entry mapping below.
 254  */
 255 void iommu_tbl_range_free(struct iommu_map_table *iommu, u64 dma_addr,
 256                           unsigned long npages, unsigned long entry)
 257 {
 258         struct iommu_pool *pool;
 259         unsigned long flags;
 260         unsigned long shift = iommu->table_shift;
 261
 262         if (entry == DMA_ERROR_CODE) /* use default addr->entry mapping */
 263                 entry = (dma_addr - iommu->table_map_base) >> shift;
 264         pool = get_pool(iommu, entry);
 265
 266         spin_lock_irqsave(&(pool->lock), flags);
 267         bitmap_clear(iommu->map, entry, npages);
 268         spin_unlock_irqrestore(&(pool->lock), flags);
 269 }
 270 EXPORT_SYMBOL(iommu_tbl_range_free);