LXR qemu/hw/mem/sparse-mem.c

   1/*
   2 * A sparse memory device. Useful for fuzzing
   3 *
   4 * Copyright Red Hat Inc., 2021
   5 *
   6 * Authors:
   7 *  Alexander Bulekov   <alxndr@bu.edu>
   8 *
   9 * This work is licensed under the terms of the GNU GPL, version 2 or later.
  10 * See the COPYING file in the top-level directory.
  11 */
  12
  13#include "qemu/osdep.h"
  14#include "qemu/error-report.h"
  15
  16#include "hw/qdev-properties.h"
  17#include "hw/sysbus.h"
  18#include "qapi/error.h"
  19#include "qemu/units.h"
  20#include "sysemu/qtest.h"
  21#include "hw/mem/sparse-mem.h"
  22
  23#define SPARSE_MEM(obj) OBJECT_CHECK(SparseMemState, (obj), TYPE_SPARSE_MEM)
  24#define SPARSE_BLOCK_SIZE 0x1000
  25
  26typedef struct SparseMemState {
  27    SysBusDevice parent_obj;
  28    MemoryRegion mmio;
  29    uint64_t baseaddr;
  30    uint64_t length;
  31    uint64_t size_used;
  32    uint64_t maxsize;
  33    GHashTable *mapped;
  34} SparseMemState;
  35
  36typedef struct sparse_mem_block {
  37    uint8_t data[SPARSE_BLOCK_SIZE];
  38} sparse_mem_block;
  39
  40static uint64_t sparse_mem_read(void *opaque, hwaddr addr, unsigned int size)
  41{
  42    SparseMemState *s = opaque;
  43    uint64_t ret = 0;
  44    size_t pfn = addr / SPARSE_BLOCK_SIZE;
  45    size_t offset = addr % SPARSE_BLOCK_SIZE;
  46    sparse_mem_block *block;
  47
  48    block = g_hash_table_lookup(s->mapped, (void *)pfn);
  49    if (block) {
  50        assert(offset + size <= sizeof(block->data));
  51        memcpy(&ret, block->data + offset, size);
  52    }
  53    return ret;
  54}
  55
  56static void sparse_mem_write(void *opaque, hwaddr addr, uint64_t v,
  57                             unsigned int size)
  58{
  59    SparseMemState *s = opaque;
  60    size_t pfn = addr / SPARSE_BLOCK_SIZE;
  61    size_t offset = addr % SPARSE_BLOCK_SIZE;
  62    sparse_mem_block *block;
  63
  64    if (!g_hash_table_lookup(s->mapped, (void *)pfn) &&
  65        s->size_used + SPARSE_BLOCK_SIZE < s->maxsize && v) {
  66        g_hash_table_insert(s->mapped, (void *)pfn,
  67                            g_new0(sparse_mem_block, 1));
  68        s->size_used += sizeof(block->data);
  69    }
  70    block = g_hash_table_lookup(s->mapped, (void *)pfn);
  71    if (!block) {
  72        return;
  73    }
  74
  75    assert(offset + size <= sizeof(block->data));
  76
  77    memcpy(block->data + offset, &v, size);
  78
  79}
  80
  81static void sparse_mem_enter_reset(Object *obj, ResetType type)
  82{
  83    SparseMemState *s = SPARSE_MEM(obj);
  84    g_hash_table_remove_all(s->mapped);
  85    return;
  86}
  87
  88static const MemoryRegionOps sparse_mem_ops = {
  89    .read = sparse_mem_read,
  90    .write = sparse_mem_write,
  91    .endianness = DEVICE_LITTLE_ENDIAN,
  92    .valid = {
  93            .min_access_size = 1,
  94            .max_access_size = 8,
  95            .unaligned = false,
  96        },
  97};
  98
  99static Property sparse_mem_properties[] = {
 100    /* The base address of the memory */
 101    DEFINE_PROP_UINT64("baseaddr", SparseMemState, baseaddr, 0x0),
 102    /* The length of the sparse memory region */
 103    DEFINE_PROP_UINT64("length", SparseMemState, length, UINT64_MAX),
 104    /* Max amount of actual memory that can be used to back the sparse memory */
 105    DEFINE_PROP_UINT64("maxsize", SparseMemState, maxsize, 10 * MiB),
 106    DEFINE_PROP_END_OF_LIST(),
 107};
 108
 109MemoryRegion *sparse_mem_init(uint64_t addr, uint64_t length)
 110{
 111    DeviceState *dev;
 112
 113    dev = qdev_new(TYPE_SPARSE_MEM);
 114    qdev_prop_set_uint64(dev, "baseaddr", addr);
 115    qdev_prop_set_uint64(dev, "length", length);
 116    sysbus_realize_and_unref(SYS_BUS_DEVICE(dev), &error_fatal);
 117    sysbus_mmio_map_overlap(SYS_BUS_DEVICE(dev), 0, addr, -10000);
 118    return &SPARSE_MEM(dev)->mmio;
 119}
 120
 121static void sparse_mem_realize(DeviceState *dev, Error **errp)
 122{
 123    SparseMemState *s = SPARSE_MEM(dev);
 124    SysBusDevice *sbd = SYS_BUS_DEVICE(dev);
 125
 126    if (!qtest_enabled()) {
 127        error_setg(errp, "sparse_mem device should only be used "
 128                         "for testing with QTest");
 129        return;
 130    }
 131
 132    assert(s->baseaddr + s->length > s->baseaddr);
 133
 134    s->mapped = g_hash_table_new_full(NULL, NULL, NULL,
 135                                      (GDestroyNotify)g_free);
 136    memory_region_init_io(&s->mmio, OBJECT(s), &sparse_mem_ops, s,
 137                          "sparse-mem", s->length);
 138    sysbus_init_mmio(sbd, &s->mmio);
 139}
 140
 141static void sparse_mem_class_init(ObjectClass *klass, void *data)
 142{
 143    ResettableClass *rc = RESETTABLE_CLASS(klass);
 144    DeviceClass *dc = DEVICE_CLASS(klass);
 145
 146    device_class_set_props(dc, sparse_mem_properties);
 147
 148    dc->desc = "Sparse Memory Device";
 149    dc->realize = sparse_mem_realize;
 150
 151    rc->phases.enter = sparse_mem_enter_reset;
 152}
 153
 154static const TypeInfo sparse_mem_types[] = {
 155    {
 156        .name = TYPE_SPARSE_MEM,
 157        .parent = TYPE_SYS_BUS_DEVICE,
 158        .instance_size = sizeof(SparseMemState),
 159        .class_init = sparse_mem_class_init,
 160    },
 161};
 162DEFINE_TYPES(sparse_mem_types);
 163