cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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vbox_hgsmi.c (2394B)

      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}