arch/powerpc/mm/vphn.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <asm/byteorder.h>
   3 #include "vphn.h"
   4
   5 /*
   6  * The associativity domain numbers are returned from the hypervisor as a
   7  * stream of mixed 16-bit and 32-bit fields. The stream is terminated by the
   8  * special value of "all ones" (aka. 0xffff) and its size may not exceed 48
   9  * bytes.
  10  *
  11  *    --- 16-bit fields -->
  12  *  _________________________
  13  *  |  0  |  1  |  2  |  3  |   be_packed[0]
  14  *  ------+-----+-----+------
  15  *  _________________________
  16  *  |  4  |  5  |  6  |  7  |   be_packed[1]
  17  *  -------------------------
  18  *            ...
  19  *  _________________________
  20  *  | 20  | 21  | 22  | 23  |   be_packed[5]
  21  *  -------------------------
  22  *
  23  * Convert to the sequence they would appear in the ibm,associativity property.
  24  */
  25 int vphn_unpack_associativity(const long *packed, __be32 *unpacked)
  26 {
  27         __be64 be_packed[VPHN_REGISTER_COUNT];
  28         int i, nr_assoc_doms = 0;
  29         const __be16 *field = (const __be16 *) be_packed;
  30         u16 last = 0;
  31         bool is_32bit = false;
  32
  33 #define VPHN_FIELD_UNUSED       (0xffff)
  34 #define VPHN_FIELD_MSB          (0x8000)
  35 #define VPHN_FIELD_MASK         (~VPHN_FIELD_MSB)
  36
  37         /* Let's fix the values returned by plpar_hcall9() */
  38         for (i = 0; i < VPHN_REGISTER_COUNT; i++)
  39                 be_packed[i] = cpu_to_be64(packed[i]);
  40
  41         for (i = 1; i < VPHN_ASSOC_BUFSIZE; i++) {
  42                 u16 new = be16_to_cpup(field++);
  43
  44                 if (is_32bit) {
  45                         /* Let's concatenate the 16 bits of this field to the
  46                          * 15 lower bits of the previous field
  47                          */
  48                         unpacked[++nr_assoc_doms] =
  49                                 cpu_to_be32(last << 16 | new);
  50                         is_32bit = false;
  51                 } else if (new == VPHN_FIELD_UNUSED)
  52                         /* This is the list terminator */
  53                         break;
  54                 else if (new & VPHN_FIELD_MSB) {
  55                         /* Data is in the lower 15 bits of this field */
  56                         unpacked[++nr_assoc_doms] =
  57                                 cpu_to_be32(new & VPHN_FIELD_MASK);
  58                 } else {
  59                         /* Data is in the lower 15 bits of this field
  60                          * concatenated with the next 16 bit field
  61                          */
  62                         last = new;
  63                         is_32bit = true;
  64                 }
  65         }
  66
  67         /* The first cell contains the length of the property */
  68         unpacked[0] = cpu_to_be32(nr_assoc_doms);
  69
  70         return nr_assoc_doms;
  71 }