palacios/src/palacios/vmm_emulator.c

   1 #include <palacios/vmm.h>
   2 #include <palacios/vmm_emulator.h>
   3 #include <palacios/vm_guest_mem.h>
   4 #include <palacios/vmm_decoder.h>
   5
   6 static const char VMMCALL[3] = {0x0f, 0x01, 0xd9};
   7
   8 int init_emulator(struct guest_info * info) {
   9   struct emulation_state * emulator = &(info->emulator);
  10
  11   emulator->num_emulated_pages = 0;
  12   INIT_LIST_HEAD(&(emulator->emulated_pages));
  13
  14
  15   emulator->num_saved_pages = 0;
  16   INIT_LIST_HEAD(&(emulator->saved_pages));
  17
  18   emulator->num_write_regions = 0;
  19   INIT_LIST_HEAD(&(emulator->write_regions));
  20
  21   emulator->running = 0;
  22   emulator->instr_length = 0;
  23
  24   return 0;
  25 }
  26
  27 static addr_t get_new_page() {
  28   void * page = V3_AllocPages(1);
  29   memset(page, 0, PAGE_SIZE);
  30
  31   return (addr_t)page;
  32 }
  33
  34
  35 static int setup_code_page(struct guest_info * info, char * instr, struct basic_instr_info * instr_info ) {
  36   addr_t code_page_offset = PT32_PAGE_OFFSET(info->rip);
  37   addr_t code_page = get_new_page();
  38   struct emulated_page * new_code_page = V3_Malloc(sizeof(struct emulated_page));
  39   struct saved_page * saved_code_page = V3_Malloc(sizeof(struct saved_page));
  40
  41
  42   saved_code_page->va = PT32_PAGE_ADDR(info->rip);
  43
  44   new_code_page->page_addr = code_page;
  45   new_code_page->va = PT32_PAGE_ADDR(info->rip);
  46
  47   new_code_page->pte.present = 1;
  48   new_code_page->pte.writable = 0;
  49   new_code_page->pte.user_page = 1;
  50   new_code_page->pte.page_base_addr = PT32_BASE_ADDR(code_page);
  51
  52   memcpy((void *)(code_page + code_page_offset), instr, instr_info->instr_length);
  53   memcpy((void *)(code_page + code_page_offset + instr_info->instr_length), VMMCALL, 3);
  54
  55   PrintDebug("New Instr Stream:\n");
  56   PrintTraceMemDump((void *)(code_page + code_page_offset), 32);
  57   PrintDebug("rip =%x\n", info->rip);
  58
  59
  60
  61
  62   v3_replace_shdw_page32(info, new_code_page->va, &(new_code_page->pte), &(saved_code_page->pte));
  63
  64
  65   list_add(&(new_code_page->page_list), &(info->emulator.emulated_pages));
  66   info->emulator.num_emulated_pages++;
  67
  68   list_add(&(saved_code_page->page_list), &(info->emulator.saved_pages));
  69   info->emulator.num_saved_pages++;
  70
  71   return 0;
  72 }
  73
  74
  75 // get the current instr
  76 // check if rep + remove
  77 // put into new page, vmexit after
  78 // replace new page with current eip page
  79 //
  80 int v3_emulate_memory_read(struct guest_info * info, addr_t read_gva,
  81                            int (*read)(addr_t read_addr, void * dst, uint_t length, void * priv_data),
  82                            addr_t read_gpa, void * private_data) {
  83   struct basic_instr_info instr_info;
  84   char instr[15];
  85   int ret;
  86   struct emulated_page * data_page = V3_Malloc(sizeof(struct emulated_page));
  87   addr_t data_addr_offset = PT32_PAGE_OFFSET(read_gva);
  88   pte32_t saved_pte;
  89
  90   PrintDebug("Emulating Read\n");
  91
  92   if (info->mem_mode == PHYSICAL_MEM) {
  93     ret = read_guest_pa_memory(info, get_addr_linear(info, info->rip, &(info->segments.cs)), 15, instr);
  94   } else {
  95     ret = read_guest_va_memory(info, get_addr_linear(info, info->rip, &(info->segments.cs)), 15, instr);
  96   }
  97
  98   PrintDebug("Instr (15 bytes) at %x:\n", instr);
  99   PrintTraceMemDump(instr, 15);
 100
 101   if (v3_basic_mem_decode(info, (addr_t)instr, &instr_info) == -1) {
 102     PrintError("Could not do a basic memory instruction decode\n");
 103     V3_Free(data_page);
 104     return -1;
 105   }
 106
 107   if (instr_info.has_rep == 1) {
 108     PrintError("We currently don't handle rep* instructions\n");
 109     V3_Free(data_page);
 110     return -1;
 111   }
 112
 113
 114   data_page->page_addr = get_new_page();
 115   data_page->va = PT32_PAGE_ADDR(read_gva);
 116   data_page->pte.present = 1;
 117   data_page->pte.writable = 0;
 118   data_page->pte.user_page = 1;
 119   data_page->pte.page_base_addr = PT32_BASE_ADDR(data_page->page_addr);
 120
 121
 122   // Read the data directly onto the emulated page
 123   if (read(read_gpa, (void *)(data_page->page_addr + data_addr_offset), instr_info.op_size, private_data) != instr_info.op_size) {
 124     PrintError("Read error in emulator\n");
 125     V3_FreePage((void *)(data_page->page_addr));
 126     V3_Free(data_page);
 127     return -1;
 128   }
 129
 130   v3_replace_shdw_page32(info, data_page->va, &(data_page->pte), &saved_pte);
 131
 132
 133   list_add(&(data_page->page_list), &(info->emulator.emulated_pages));
 134   info->emulator.num_emulated_pages++;
 135
 136   if (saved_pte.present == 1) {
 137     struct saved_page * saved_data_page = V3_Malloc(sizeof(struct saved_page));
 138     saved_data_page->pte = saved_pte;
 139     saved_data_page->va = PT32_PAGE_ADDR(read_gva);
 140
 141     list_add(&(saved_data_page->page_list), &(info->emulator.saved_pages));
 142     info->emulator.num_saved_pages++;
 143   }
 144
 145
 146   setup_code_page(info, instr, &instr_info);
 147
 148   info->emulator.running = 1;
 149   info->run_state = VM_EMULATING;
 150   info->emulator.instr_length = instr_info.instr_length;
 151
 152   return 0;
 153 }
 154
 155
 156
 157 int v3_emulate_memory_write(struct guest_info * info, addr_t write_gva,
 158                             int (*write)(addr_t write_addr, void * src, uint_t length, void * priv_data),
 159                             addr_t write_gpa, void * private_data) {
 160
 161   struct basic_instr_info instr_info;
 162   char instr[15];
 163   int ret;
 164   struct write_region * write_op = V3_Malloc(sizeof(struct write_region ));
 165   struct emulated_page * data_page = V3_Malloc(sizeof(struct emulated_page));
 166   addr_t data_addr_offset = PT32_PAGE_OFFSET(write_gva);
 167   pte32_t saved_pte;
 168
 169   PrintDebug("Emulating Write\n");
 170
 171   if (info->mem_mode == PHYSICAL_MEM) {
 172     ret = read_guest_pa_memory(info, get_addr_linear(info, info->rip, &(info->segments.cs)), 15, instr);
 173   } else {
 174     ret = read_guest_va_memory(info, get_addr_linear(info, info->rip, &(info->segments.cs)), 15, instr);
 175   }
 176
 177   if (v3_basic_mem_decode(info, (addr_t)instr, &instr_info) == -1) {
 178     PrintError("Could not do a basic memory instruction decode\n");
 179     V3_Free(write_op);
 180     V3_Free(data_page);
 181     return -1;
 182   }
 183
 184   if (instr_info.has_rep == 1) {
 185     PrintError("We currently don't handle rep* instructions\n");
 186     V3_Free(write_op);
 187     V3_Free(data_page);
 188     return -1;
 189   }
 190
 191
 192   data_page->page_addr = get_new_page();
 193   data_page->va = PT32_PAGE_ADDR(write_gva);
 194   data_page->pte.present = 1;
 195   data_page->pte.writable = 1;
 196   data_page->pte.user_page = 1;
 197   data_page->pte.page_base_addr = PT32_BASE_ADDR(data_page->page_addr);
 198
 199
 200
 201   write_op->write = write;
 202   write_op->write_addr = write_gpa;
 203   write_op->length = instr_info.op_size;
 204   write_op->private_data = private_data;
 205
 206   write_op->write_data = (void *)(data_page->page_addr + data_addr_offset);
 207
 208   list_add(&(write_op->write_list), &(info->emulator.write_regions));
 209   info->emulator.num_write_regions--;
 210
 211   v3_replace_shdw_page32(info, data_page->va, &(data_page->pte), &saved_pte);
 212
 213
 214   list_add(&(data_page->page_list), &(info->emulator.emulated_pages));
 215   info->emulator.num_emulated_pages++;
 216
 217   if (saved_pte.present == 1) {
 218     struct saved_page * saved_data_page = V3_Malloc(sizeof(struct saved_page));
 219     saved_data_page->pte = saved_pte;
 220     saved_data_page->va = PT32_PAGE_ADDR(write_gva);
 221
 222     list_add(&(saved_data_page->page_list), &(info->emulator.saved_pages));
 223     info->emulator.num_saved_pages++;
 224   }
 225
 226
 227   if (info->emulator.running == 0) {
 228     setup_code_page(info, instr, &instr_info);
 229     info->emulator.running = 1;
 230     info->run_state = VM_EMULATING;
 231     info->emulator.instr_length = instr_info.instr_length;
 232   }
 233
 234   return 0;
 235 }
 236
 237
 238 // end emulation
 239 int v3_emulation_exit_handler(struct guest_info * info) {
 240   struct saved_page * svpg, * p_svpg;
 241   struct emulated_page * empg, * p_empg;
 242   struct write_region * wr_reg, * p_wr_reg;
 243   pte32_t dummy_pte;
 244
 245   // Complete the writes
 246   // delete writes
 247   // swap out emulated pages with blank dummies
 248   // swap in saved pages
 249   // increment rip
 250
 251   PrintDebug("V3 Emulation Exit Handler\n");
 252
 253   list_for_each_entry_safe(wr_reg, p_wr_reg, &(info->emulator.write_regions), write_list) {
 254     wr_reg->write(wr_reg->write_addr, wr_reg->write_data, wr_reg->length, wr_reg->private_data);
 255     PrintDebug("Writing \n");
 256
 257     list_del(&(wr_reg->write_list));
 258     V3_Free(wr_reg);
 259
 260   }
 261   info->emulator.num_write_regions = 0;
 262
 263
 264   *(uint_t *)&dummy_pte = 0;
 265
 266   list_for_each_entry_safe(empg, p_empg, &(info->emulator.emulated_pages), page_list) {
 267     pte32_t empte32_t;
 268
 269     PrintDebug("wiping page %x\n", empg->va);
 270
 271     v3_replace_shdw_page32(info, empg->va, &dummy_pte, &empte32_t);
 272     V3_FreePage((void *)(empg->page_addr));
 273
 274     list_del(&(empg->page_list));
 275     V3_Free(empg);
 276   }
 277   info->emulator.num_emulated_pages = 0;
 278
 279   list_for_each_entry_safe(svpg, p_svpg, &(info->emulator.saved_pages), page_list) {
 280
 281     PrintDebug("Setting Saved page %x back\n", svpg->va);
 282     v3_replace_shdw_page32(info, empg->va, &(svpg->pte), &dummy_pte);
 283
 284     list_del(&(svpg->page_list));
 285     V3_Free(svpg);
 286   }
 287   info->emulator.num_saved_pages = 0;
 288
 289   info->run_state = VM_RUNNING;
 290   info->emulator.running = 0;
 291   //info->rip += info->emulator.instr_length;
 292
 293   info->emulator.instr_length = 0;
 294
 295   PrintDebug("returning from emulation\n");
 296
 297   return 0;
 298 }