LXR linux/arch/powerpc/platforms/pseries/vphn.c

   1// SPDX-License-Identifier: GPL-2.0
   2#include <asm/byteorder.h>
   3#include <asm/lppaca.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 */
  25static 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                        /*
  46                         * Let's concatenate the 16 bits of this field to the
  47                         * 15 lower bits of the previous field
  48                         */
  49                        unpacked[++nr_assoc_doms] =
  50                                cpu_to_be32(last << 16 | new);
  51                        is_32bit = false;
  52                } else if (new == VPHN_FIELD_UNUSED)
  53                        /* This is the list terminator */
  54                        break;
  55                else if (new & VPHN_FIELD_MSB) {
  56                        /* Data is in the lower 15 bits of this field */
  57                        unpacked[++nr_assoc_doms] =
  58                                cpu_to_be32(new & VPHN_FIELD_MASK);
  59                } else {
  60                        /*
  61                         * Data is in the lower 15 bits of this field
  62                         * concatenated with the next 16 bit field
  63                         */
  64                        last = new;
  65                        is_32bit = true;
  66                }
  67        }
  68
  69        /* The first cell contains the length of the property */
  70        unpacked[0] = cpu_to_be32(nr_assoc_doms);
  71
  72        return nr_assoc_doms;
  73}
  74
  75/* NOTE: This file is included by a selftest and built in userspace. */
  76#ifdef __KERNEL__
  77#include <asm/hvcall.h>
  78
  79long hcall_vphn(unsigned long cpu, u64 flags, __be32 *associativity)
  80{
  81        long rc;
  82        long retbuf[PLPAR_HCALL9_BUFSIZE] = {0};
  83
  84        rc = plpar_hcall9(H_HOME_NODE_ASSOCIATIVITY, retbuf, flags, cpu);
  85        if (rc == H_SUCCESS)
  86                vphn_unpack_associativity(retbuf, associativity);
  87
  88        return rc;
  89}
  90#endif
  91