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 15 #include "exec/address-spaces.h" 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 26 typedef 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 36 typedef struct sparse_mem_block { 37 uint8_t data[SPARSE_BLOCK_SIZE]; 38 } sparse_mem_block; 39 40 static 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 56 static 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 81 static const MemoryRegionOps sparse_mem_ops = { 82 .read = sparse_mem_read, 83 .write = sparse_mem_write, 84 .endianness = DEVICE_LITTLE_ENDIAN, 85 .valid = { 86 .min_access_size = 1, 87 .max_access_size = 8, 88 .unaligned = false, 89 }, 90 }; 91 92 static Property sparse_mem_properties[] = { 93 /* The base address of the memory */ 94 DEFINE_PROP_UINT64("baseaddr", SparseMemState, baseaddr, 0x0), 95 /* The length of the sparse memory region */ 96 DEFINE_PROP_UINT64("length", SparseMemState, length, UINT64_MAX), 97 /* Max amount of actual memory that can be used to back the sparse memory */ 98 DEFINE_PROP_UINT64("maxsize", SparseMemState, maxsize, 10 * MiB), 99 DEFINE_PROP_END_OF_LIST(), 100 }; 101 102 MemoryRegion *sparse_mem_init(uint64_t addr, uint64_t length) 103 { 104 DeviceState *dev; 105 106 dev = qdev_new(TYPE_SPARSE_MEM); 107 qdev_prop_set_uint64(dev, "baseaddr", addr); 108 qdev_prop_set_uint64(dev, "length", length); 109 sysbus_realize_and_unref(SYS_BUS_DEVICE(dev), &error_fatal); 110 sysbus_mmio_map_overlap(SYS_BUS_DEVICE(dev), 0, addr, -10000); 111 return &SPARSE_MEM(dev)->mmio; 112 } 113 114 static void sparse_mem_realize(DeviceState *dev, Error **errp) 115 { 116 SparseMemState *s = SPARSE_MEM(dev); 117 SysBusDevice *sbd = SYS_BUS_DEVICE(dev); 118 119 if (!qtest_enabled()) { 120 error_setg(errp, "sparse_mem device should only be used " 121 "for testing with QTest"); 122 return; 123 } 124 125 assert(s->baseaddr + s->length > s->baseaddr); 126 127 s->mapped = g_hash_table_new(NULL, NULL); 128 memory_region_init_io(&s->mmio, OBJECT(s), &sparse_mem_ops, s, 129 "sparse-mem", s->length); 130 sysbus_init_mmio(sbd, &s->mmio); 131 } 132 133 static void sparse_mem_class_init(ObjectClass *klass, void *data) 134 { 135 DeviceClass *dc = DEVICE_CLASS(klass); 136 137 device_class_set_props(dc, sparse_mem_properties); 138 139 dc->desc = "Sparse Memory Device"; 140 dc->realize = sparse_mem_realize; 141 } 142 143 static const TypeInfo sparse_mem_types[] = { 144 { 145 .name = TYPE_SPARSE_MEM, 146 .parent = TYPE_SYS_BUS_DEVICE, 147 .instance_size = sizeof(SparseMemState), 148 .class_init = sparse_mem_class_init, 149 }, 150 }; 151 DEFINE_TYPES(sparse_mem_types); 152