1// SPDX-License-Identifier: MIT
2/*
3 * Copyright (C) 2017 Oracle Corporation
4 * Authors: Hans de Goede <hdegoede@redhat.com>
5 */
6
7#include "vbox_drv.h"
8#include "vboxvideo_vbe.h"
9#include "hgsmi_defs.h"
10
11/* One-at-a-Time Hash from https://www.burtleburtle.net/bob/hash/doobs.html */
12static u32 hgsmi_hash_process(u32 hash, const u8 *data, int size)
13{
14	while (size--) {
15		hash += *data++;
16		hash += (hash << 10);
17		hash ^= (hash >> 6);
18	}
19
20	return hash;
21}
22
23static u32 hgsmi_hash_end(u32 hash)
24{
25	hash += (hash << 3);
26	hash ^= (hash >> 11);
27	hash += (hash << 15);
28
29	return hash;
30}
31
32/* Not really a checksum but that is the naming used in all vbox code */
33static u32 hgsmi_checksum(u32 offset,
34			  const struct hgsmi_buffer_header *header,
35			  const struct hgsmi_buffer_tail *tail)
36{
37	u32 checksum;
38
39	checksum = hgsmi_hash_process(0, (u8 *)&offset, sizeof(offset));
40	checksum = hgsmi_hash_process(checksum, (u8 *)header, sizeof(*header));
41	/* 4 -> Do not checksum the checksum itself */
42	checksum = hgsmi_hash_process(checksum, (u8 *)tail, 4);
43
44	return hgsmi_hash_end(checksum);
45}
46
47void *hgsmi_buffer_alloc(struct gen_pool *guest_pool, size_t size,
48			 u8 channel, u16 channel_info)
49{
50	struct hgsmi_buffer_header *h;
51	struct hgsmi_buffer_tail *t;
52	size_t total_size;
53	dma_addr_t offset;
54
55	total_size = size + sizeof(*h) + sizeof(*t);
56	h = gen_pool_dma_alloc(guest_pool, total_size, &offset);
57	if (!h)
58		return NULL;
59
60	t = (struct hgsmi_buffer_tail *)((u8 *)h + sizeof(*h) + size);
61
62	h->flags = HGSMI_BUFFER_HEADER_F_SEQ_SINGLE;
63	h->data_size = size;
64	h->channel = channel;
65	h->channel_info = channel_info;
66	memset(&h->u.header_data, 0, sizeof(h->u.header_data));
67
68	t->reserved = 0;
69	t->checksum = hgsmi_checksum(offset, h, t);
70
71	return (u8 *)h + sizeof(*h);
72}
73
74void hgsmi_buffer_free(struct gen_pool *guest_pool, void *buf)
75{
76	struct hgsmi_buffer_header *h =
77		(struct hgsmi_buffer_header *)((u8 *)buf - sizeof(*h));
78	size_t total_size = h->data_size + sizeof(*h) +
79					     sizeof(struct hgsmi_buffer_tail);
80
81	gen_pool_free(guest_pool, (unsigned long)h, total_size);
82}
83
84int hgsmi_buffer_submit(struct gen_pool *guest_pool, void *buf)
85{
86	phys_addr_t offset;
87
88	offset = gen_pool_virt_to_phys(guest_pool, (unsigned long)buf -
89				       sizeof(struct hgsmi_buffer_header));
90	outl(offset, VGA_PORT_HGSMI_GUEST);
91	/* Make the compiler aware that the host has changed memory. */
92	mb();
93
94	return 0;
95}
96