15a1ea477SNaveen N. Rao// 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