drm/vboxvideo/vbox_hgsmi.c

0001 // SPDX-License-Identifier: MIT
0002 /*
0003  * Copyright (C) 2017 Oracle Corporation
0004  * Authors: Hans de Goede <hdegoede@redhat.com>
0005  */
0006
0007 #include "vbox_drv.h"
0008 #include "vboxvideo_vbe.h"
0009 #include "hgsmi_defs.h"
0010
0011 /* One-at-a-Time Hash from https://www.burtleburtle.net/bob/hash/doobs.html */
0012 static u32 hgsmi_hash_process(u32 hash, const u8 *data, int size)
0013 {
0014     while (size--) {
0015         hash += *data++;
0016         hash += (hash << 10);
0017         hash ^= (hash >> 6);
0018     }
0019
0020     return hash;
0021 }
0022
0023 static u32 hgsmi_hash_end(u32 hash)
0024 {
0025     hash += (hash << 3);
0026     hash ^= (hash >> 11);
0027     hash += (hash << 15);
0028
0029     return hash;
0030 }
0031
0032 /* Not really a checksum but that is the naming used in all vbox code */
0033 static u32 hgsmi_checksum(u32 offset,
0034               const struct hgsmi_buffer_header *header,
0035               const struct hgsmi_buffer_tail *tail)
0036 {
0037     u32 checksum;
0038
0039     checksum = hgsmi_hash_process(0, (u8 *)&offset, sizeof(offset));
0040     checksum = hgsmi_hash_process(checksum, (u8 *)header, sizeof(*header));
0041     /* 4 -> Do not checksum the checksum itself */
0042     checksum = hgsmi_hash_process(checksum, (u8 *)tail, 4);
0043
0044     return hgsmi_hash_end(checksum);
0045 }
0046
0047 void *hgsmi_buffer_alloc(struct gen_pool *guest_pool, size_t size,
0048              u8 channel, u16 channel_info)
0049 {
0050     struct hgsmi_buffer_header *h;
0051     struct hgsmi_buffer_tail *t;
0052     size_t total_size;
0053     dma_addr_t offset;
0054
0055     total_size = size + sizeof(*h) + sizeof(*t);
0056     h = gen_pool_dma_alloc(guest_pool, total_size, &offset);
0057     if (!h)
0058         return NULL;
0059
0060     t = (struct hgsmi_buffer_tail *)((u8 *)h + sizeof(*h) + size);
0061
0062     h->flags = HGSMI_BUFFER_HEADER_F_SEQ_SINGLE;
0063     h->data_size = size;
0064     h->channel = channel;
0065     h->channel_info = channel_info;
0066     memset(&h->u.header_data, 0, sizeof(h->u.header_data));
0067
0068     t->reserved = 0;
0069     t->checksum = hgsmi_checksum(offset, h, t);
0070
0071     return (u8 *)h + sizeof(*h);
0072 }
0073
0074 void hgsmi_buffer_free(struct gen_pool *guest_pool, void *buf)
0075 {
0076     struct hgsmi_buffer_header *h =
0077         (struct hgsmi_buffer_header *)((u8 *)buf - sizeof(*h));
0078     size_t total_size = h->data_size + sizeof(*h) +
0079                          sizeof(struct hgsmi_buffer_tail);
0080
0081     gen_pool_free(guest_pool, (unsigned long)h, total_size);
0082 }
0083
0084 int hgsmi_buffer_submit(struct gen_pool *guest_pool, void *buf)
0085 {
0086     phys_addr_t offset;
0087
0088     offset = gen_pool_virt_to_phys(guest_pool, (unsigned long)buf -
0089                        sizeof(struct hgsmi_buffer_header));
0090     outl(offset, VGA_PORT_HGSMI_GUEST);
0091     /* Make the compiler aware that the host has changed memory. */
0092     mb();
0093
0094     return 0;
0095 }