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 */
12 static 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 
23 static 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 */
33 static 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 
47 void *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 
74 void 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 
84 int 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