Palacios Public Git Repository

To checkout Palacios execute

  git clone http://v3vee.org/palacios/palacios.web/palacios.git
This will give you the master branch. You probably want the devel branch or one of the release branches. To switch to the devel branch, simply execute
  cd palacios
  git checkout --track -b devel origin/devel
The other branches are similar.


working instruction emulation
[palacios.git] / palacios / src / palacios / vmm_emulator.c
index 97549eb..bb67a5f 100644 (file)
 #include <palacios/vmm_emulator.h>
 #include <palacios/vm_guest_mem.h>
 #include <palacios/vmm_decoder.h>
-#include <palacios/vmm_debug.h>
-#include <palacios/vmcb.h>
-#include <palacios/vmm_ctrl_regs.h>
-
-static const char VMMCALL[3] = {0x0f, 0x01, 0xd9};
+#include <palacios/vmm_paging.h>
+#include <palacios/vmm_instr_emulator.h>
 
 #ifndef DEBUG_EMULATOR
 #undef PrintDebug
@@ -33,120 +30,121 @@ static const char VMMCALL[3] = {0x0f, 0x01, 0xd9};
 #endif
 
 
-int v3_init_emulator(struct guest_info * info) {
-  struct emulation_state * emulator = &(info->emulator);
-
-  emulator->num_emulated_pages = 0;
-  INIT_LIST_HEAD(&(emulator->emulated_pages));
-
 
-  emulator->num_saved_pages = 0;
-  INIT_LIST_HEAD(&(emulator->saved_pages));
-  
-  emulator->num_write_regions = 0;
-  INIT_LIST_HEAD(&(emulator->write_regions));
 
-  emulator->running = 0;
-  emulator->instr_length = 0;
 
-  emulator->tf_enabled = 0;
 
-  return 0;
-}
+// We emulate up to the next 4KB page boundry
+static int emulate_string_write_op(struct guest_info * info, struct x86_instr * dec_instr, 
+                                  addr_t write_gva, addr_t write_gpa, addr_t * dst_addr) {
+  uint_t emulation_length = 0;
+  addr_t tmp_rcx = 0;
+  addr_t src_addr = 0;
 
-static addr_t get_new_page() {
-  void * page = V3_VAddr(V3_AllocPages(1));
-  memset(page, 0, PAGE_SIZE);
+  if (dec_instr->op_type == V3_OP_MOVS) {
+    PrintDebug("MOVS emulation\n");
 
-  return (addr_t)page;
-}
+    if (dec_instr->dst_operand.operand != write_gva) {
+      PrintError("Inconsistency between Pagefault and Instruction Decode XED_ADDR=%p, PF_ADDR=%p\n",
+                (void *)dec_instr->dst_operand.operand, (void *)write_gva);
+      return -1;
+    }
 
-/*
-static int setup_code_page(struct guest_info * info, char * instr, struct basic_instr_info * instr_info ) {
-  addr_t code_page_offset = PT32_PAGE_OFFSET(info->rip);
-  addr_t code_page = get_new_page();
-  struct emulated_page * new_code_page = V3_Malloc(sizeof(struct emulated_page));
-  struct saved_page * saved_code_page = V3_Malloc(sizeof(struct saved_page));
+    emulation_length = ( (dec_instr->str_op_length  < (0x1000 - PAGE_OFFSET_4KB(write_gva))) ? 
+                        dec_instr->str_op_length :
+                        (0x1000 - PAGE_OFFSET_4KB(write_gva)));
+    /* ** Fix emulation length so that it doesn't overrun over the src page either ** */
 
 
-  saved_code_page->va = PT32_PAGE_ADDR(info->rip);
-
-  new_code_page->page_addr = code_page; 
-  new_code_page->va = PT32_PAGE_ADDR(info->rip);
-
-  new_code_page->pte.present = 1;
-  new_code_page->pte.writable = 0;
-  new_code_page->pte.user_page = 1;
-  new_code_page->pte.page_base_addr = PT32_BASE_ADDR(code_page);
-
-  memcpy((void *)(code_page + code_page_offset), instr, instr_info->instr_length);
-  memcpy((void *)(code_page + code_page_offset + instr_info->instr_length), VMMCALL, 3);
-
-#ifdef DEBUG_EMULATOR
-  PrintDebug("New Instr Stream:\n");
-  PrintTraceMemDump((void *)(code_page + code_page_offset), 32);
-  PrintDebug("rip =%x\n", info->rip);
-#endif
+    PrintDebug("STR_OP_LEN: %d, Page Len: %d\n", 
+              (uint_t)dec_instr->str_op_length, 
+              (uint_t)(0x1000 - PAGE_OFFSET_4KB(write_gva)));
+    PrintDebug("Emulation length: %d\n", emulation_length);
+    tmp_rcx = emulation_length;
+    if (guest_pa_to_host_va(info, write_gpa, dst_addr) == -1) {
+      PrintError("Could not translate write destination to host VA\n");
+      return -1;
+    }
 
+    // figure out addresses here....
+    if (info->mem_mode == PHYSICAL_MEM) {
+      if (guest_pa_to_host_va(info, dec_instr->src_operand.operand, &src_addr) == -1) {
+       PrintError("Could not translate write Source (Physical) to host VA\n");
+       return -1;
+      }
+    } else {
+      if (guest_va_to_host_va(info, dec_instr->src_operand.operand, &src_addr) == -1) {
+       PrintError("Could not translate write Source (Virtual) to host VA\n");
+       return -1;
+      }
+    }
 
 
-  v3_replace_shdw_page32(info, new_code_page->va, &(new_code_page->pte), &(saved_code_page->pte));
+    PrintDebug("Dst Operand: %p (size=%d), Src Operand: %p\n", 
+              (void *)dec_instr->dst_operand.operand, 
+              dec_instr->dst_operand.size,
+              (void *)dec_instr->src_operand.operand);
+    PrintDebug("Dst Addr: %p, Src Addr: %p\n", (void *)(addr_t *)*dst_addr, (void *)src_addr);
 
+    //return -1;
 
-  list_add(&(new_code_page->page_list), &(info->emulator.emulated_pages));
-  info->emulator.num_emulated_pages++;
 
-  list_add(&(saved_code_page->page_list), &(info->emulator.saved_pages));
-  info->emulator.num_saved_pages++;
 
-  return 0;
-}
-*/
 
+    if (dec_instr->dst_operand.size == 1) {
+      movs8(dst_addr, &src_addr, &tmp_rcx, (addr_t *)&(info->ctrl_regs.rflags));
+    } else if (dec_instr->dst_operand.size == 2) {
+      movs16(dst_addr, &src_addr, &tmp_rcx, (addr_t *)&(info->ctrl_regs.rflags));
+    } else if (dec_instr->dst_operand.size == 4) {
+      movs32(dst_addr, &src_addr, &tmp_rcx, (addr_t *)&(info->ctrl_regs.rflags));
+    } else {
+      PrintError("Invalid operand length\n");
+      return -1;
+    }
 
-static int set_stepping(struct guest_info * info) {
-  vmcb_ctrl_t * ctrl_area = GET_VMCB_CTRL_AREA((vmcb_t*)(info->vmm_data));
-  ctrl_area->exceptions.db = 1;
 
-  info->emulator.tf_enabled = ((struct rflags *)&(info->ctrl_regs.rflags))->tf;
 
-  ((struct rflags *)&(info->ctrl_regs.rflags))->tf = 1;
 
-  return 0;
-}
 
+    PrintDebug("RDI=%p, RSI=%p, RCX=%p\n", 
+              (void *)*(addr_t *)&(info->vm_regs.rdi), 
+              (void *)*(addr_t *)&(info->vm_regs.rsi), 
+              (void *)*(addr_t *)&(info->vm_regs.rcx)); 
 
-static int unset_stepping(struct guest_info * info) {
-  vmcb_ctrl_t * ctrl_area = GET_VMCB_CTRL_AREA((vmcb_t*)(info->vmm_data));
-  ctrl_area->exceptions.db = 0;
+    info->vm_regs.rdi += emulation_length;
+    info->vm_regs.rsi += emulation_length;
+    info->vm_regs.rcx -= emulation_length;
+    
+    PrintDebug("RDI=%p, RSI=%p, RCX=%p\n", 
+              (void *)*(addr_t *)&(info->vm_regs.rdi), 
+              (void *)*(addr_t *)&(info->vm_regs.rsi), 
+              (void *)*(addr_t *)&(info->vm_regs.rcx)); 
 
-  ((struct rflags *)&(info->ctrl_regs.rflags))->tf = info->emulator.tf_enabled;
+    if (emulation_length == dec_instr->str_op_length) {
+      info->rip += dec_instr->instr_length;
+    }
 
-  if (info->emulator.tf_enabled) {
-    // Inject breakpoint exception into guest
+    return emulation_length;
   }
 
-  return 0;
+  
+
 
+  return -1;
 }
 
 
-// get the current instr
-// check if rep + remove
-// put into new page, vmexit after
-// replace new page with current eip page
-// 
-int v3_emulate_memory_read(struct guest_info * info, addr_t read_gva, 
-                          int (*read)(addr_t read_addr, void * dst, uint_t length, void * priv_data), 
-                          addr_t read_gpa, void * private_data) {
-  struct basic_instr_info instr_info;
+int v3_emulate_write_op(struct guest_info * info, addr_t write_gva, addr_t write_gpa, addr_t * dst_addr) {
+  struct x86_instr dec_instr;
   uchar_t instr[15];
-  int ret;
-  struct emulated_page * data_page = V3_Malloc(sizeof(struct emulated_page));
-  addr_t data_addr_offset = PAGE_OFFSET(read_gva);
-  pte32_t saved_pte;
+  int ret = 0;
+  addr_t src_addr = 0;
+
 
-  PrintDebug("Emulating Read\n");
+  PrintDebug("Emulating Write for instruction at %p\n", (void *)(addr_t)(info->rip));
+  PrintDebug("GPA=%p, GVA=%p\n", (void *)write_gpa, (void *)write_gva);
 
   if (info->mem_mode == PHYSICAL_MEM) { 
     ret = read_guest_pa_memory(info, get_addr_linear(info, info->rip, &(info->segments.cs)), 15, instr);
@@ -155,233 +153,258 @@ int v3_emulate_memory_read(struct guest_info * info, addr_t read_gva,
   }
 
   if (ret == -1) {
-    PrintError("Could not read guest memory\n");
     return -1;
   }
 
-#ifdef DEBUG_EMULATOR
-  PrintDebug("Instr (15 bytes) at %p:\n", (void *)(addr_t)instr);
-  PrintTraceMemDump(instr, 15);
-#endif  
 
-
-  if (v3_basic_mem_decode(info, (addr_t)instr, &instr_info) == -1) {
-    PrintError("Could not do a basic memory instruction decode\n");
-    V3_Free(data_page);
+  if (guest_pa_to_host_va(info, write_gpa, dst_addr) == -1) {
+    PrintError("Could not translate write destination to host VA\n");
     return -1;
   }
 
-  /*
-  if (instr_info.has_rep == 1) {
-    PrintError("We currently don't handle rep* instructions\n");
-    V3_Free(data_page);
+  if (v3_decode(info, (addr_t)instr, &dec_instr) == -1) {
+    PrintError("Decoding Error\n");
+    // Kick off single step emulator
     return -1;
   }
-  */
-
-  data_page->page_addr = get_new_page();
-  data_page->va = PAGE_ADDR(read_gva);
-  data_page->pte.present = 1;
-  data_page->pte.writable = 0;
-  data_page->pte.user_page = 1;
-  data_page->pte.page_base_addr = PAGE_BASE_ADDR((addr_t)V3_PAddr((void *)(addr_t)(data_page->page_addr)));
-
-
-  // Read the data directly onto the emulated page
-  ret = read(read_gpa, (void *)(data_page->page_addr + data_addr_offset), instr_info.op_size, private_data);
-  if ((ret == -1) || ((uint_t)ret != instr_info.op_size)) {
-    PrintError("Read error in emulator\n");
-    V3_FreePage((void *)V3_PAddr((void *)(data_page->page_addr)));
-    V3_Free(data_page);
-    return -1;
+  
+  if (dec_instr.is_str_op) {
+    return emulate_string_write_op(info, &dec_instr, write_gva, write_gpa, dst_addr);
   }
 
-  v3_replace_shdw_page32(info, data_page->va, &(data_page->pte), &saved_pte);
-
-
-  list_add(&(data_page->page_list), &(info->emulator.emulated_pages));
-  info->emulator.num_emulated_pages++;
 
-  if (saved_pte.present == 1) {
-    struct saved_page * saved_data_page = V3_Malloc(sizeof(struct saved_page));
-    saved_data_page->pte = saved_pte;
-    saved_data_page->va = PAGE_ADDR(read_gva);
-
-    list_add(&(saved_data_page->page_list), &(info->emulator.saved_pages));
-    info->emulator.num_saved_pages++;
+  if ((dec_instr.dst_operand.type != MEM_OPERAND) ||
+      (dec_instr.dst_operand.operand != write_gva)) {
+    PrintError("Inconsistency between Pagefault and Instruction Decode XED_ADDR=%p, PF_ADDR=%p\n",
+              (void *)dec_instr.dst_operand.operand, (void *)write_gva);
+    return -1;
   }
 
 
-  // setup_code_page(info, instr, &instr_info);
-  set_stepping(info);
-
-  info->emulator.running = 1;
-  info->run_state = VM_EMULATING;
-  info->emulator.instr_length = instr_info.instr_length;
-
-  return 0;
-}
-
-
-
-int v3_emulate_memory_write(struct guest_info * info, addr_t write_gva,
-                           int (*write)(addr_t write_addr, void * src, uint_t length, void * priv_data), 
-                           addr_t write_gpa, void * private_data) {
-
-  struct basic_instr_info instr_info;
-  uchar_t instr[15];
-  int ret;
-  struct write_region * write_op = V3_Malloc(sizeof(struct write_region ));
-  struct emulated_page * data_page = V3_Malloc(sizeof(struct emulated_page));
-  addr_t data_addr_offset = PAGE_OFFSET(write_gva);
-  pte32_t saved_pte;
-  int i;
-
-  PrintDebug("Emulating Write for instruction at 0x%p\n", (void *)(addr_t)(info->rip));
-
-  if (info->mem_mode == PHYSICAL_MEM) { 
-    ret = read_guest_pa_memory(info, get_addr_linear(info, info->rip, &(info->segments.cs)), 15, instr);
-  } else { 
-    ret = read_guest_va_memory(info, get_addr_linear(info, info->rip, &(info->segments.cs)), 15, instr);
+  if (dec_instr.src_operand.type == MEM_OPERAND) {
+    if (info->mem_mode == PHYSICAL_MEM) {
+      if (guest_pa_to_host_va(info, dec_instr.src_operand.operand, &src_addr) == -1) {
+       PrintError("Could not translate write Source (Physical) to host VA\n");
+       return -1;
+      }
+    } else {
+      if (guest_va_to_host_va(info, dec_instr.src_operand.operand, &src_addr) == -1) {
+       PrintError("Could not translate write Source (Virtual) to host VA\n");
+       return -1;
+      }
+    }
+  } else if (dec_instr.src_operand.type == REG_OPERAND) {
+    src_addr = dec_instr.src_operand.operand;
+  } else {
+    src_addr = (addr_t)&(dec_instr.src_operand.operand);
   }
 
 
-  PrintDebug("Instruction is");
-  for (i=0;i<15;i++) { PrintDebug(" 0x%x",instr[i]); } 
-  PrintDebug("\n");
-  
-  if (v3_basic_mem_decode(info, (addr_t)instr, &instr_info) == -1) {
-    PrintError("Could not do a basic memory instruction decode\n");
-    V3_Free(write_op);
-    V3_Free(data_page);
+  PrintDebug("Dst_Addr Ptr = %p (val=%p), SRC operand = %p\n", 
+            (void *)dst_addr, (void *)*dst_addr, (void *)src_addr);
+
+
+  if (dec_instr.dst_operand.size == 1) {
+
+    switch (dec_instr.op_type) {
+    case V3_OP_ADC:
+      adc8((addr_t *)*dst_addr, (addr_t *)src_addr, (addr_t *)&(info->ctrl_regs.rflags));
+      break;
+    case V3_OP_ADD:
+      add8((addr_t *)*dst_addr, (addr_t *)src_addr, (addr_t *)&(info->ctrl_regs.rflags));
+      break;
+    case V3_OP_AND:
+      and8((addr_t *)*dst_addr, (addr_t *)src_addr, (addr_t *)&(info->ctrl_regs.rflags));
+      break;
+    case V3_OP_OR:
+      or8((addr_t *)*dst_addr, (addr_t *)src_addr, (addr_t *)&(info->ctrl_regs.rflags));
+      break;
+    case V3_OP_XOR:
+      xor8((addr_t *)*dst_addr, (addr_t *)src_addr, (addr_t *)&(info->ctrl_regs.rflags));
+      break;
+    case V3_OP_SUB:
+      sub8((addr_t *)*dst_addr, (addr_t *)src_addr, (addr_t *)&(info->ctrl_regs.rflags));
+      break;
+
+    case V3_OP_MOV:
+      mov8((addr_t *)*dst_addr, (addr_t *)src_addr);
+      break;
+    case V3_OP_NOT:
+      not8((addr_t *)*dst_addr);
+      break;
+    case V3_OP_XCHG:
+      xchg8((addr_t *)*dst_addr, (addr_t *)src_addr);
+      break;
+      
+
+    case V3_OP_INC:
+      inc8((addr_t *)*dst_addr, (addr_t *)&(info->ctrl_regs.rflags));
+      break;
+    case V3_OP_DEC:
+      dec8((addr_t *)*dst_addr, (addr_t *)&(info->ctrl_regs.rflags));
+      break;
+    case V3_OP_NEG:
+      neg8((addr_t *)*dst_addr, (addr_t *)&(info->ctrl_regs.rflags));
+      break;
+    case V3_OP_SETB:
+      setb8((addr_t *)*dst_addr, (addr_t *)&(info->ctrl_regs.rflags));
+      break;
+    case V3_OP_SETBE:
+      setbe8((addr_t *)*dst_addr, (addr_t *)&(info->ctrl_regs.rflags));
+      break;
+    case V3_OP_SETL:
+      setl8((addr_t *)*dst_addr, (addr_t *)&(info->ctrl_regs.rflags));
+      break;
+    case V3_OP_SETLE:
+      setle8((addr_t *)*dst_addr, (addr_t *)&(info->ctrl_regs.rflags));
+      break;
+    case V3_OP_SETNB:
+      setnb8((addr_t *)*dst_addr, (addr_t *)&(info->ctrl_regs.rflags));
+      break;
+    case V3_OP_SETNBE:
+      setnbe8((addr_t *)*dst_addr, (addr_t *)&(info->ctrl_regs.rflags));
+      break;
+    case V3_OP_SETNL:
+      setnl8((addr_t *)*dst_addr, (addr_t *)&(info->ctrl_regs.rflags));
+      break;
+    case V3_OP_SETNLE:
+      setnle8((addr_t *)*dst_addr, (addr_t *)&(info->ctrl_regs.rflags));
+      break;
+    case V3_OP_SETNO:
+      setno8((addr_t *)*dst_addr, (addr_t *)&(info->ctrl_regs.rflags));
+      break;
+    case V3_OP_SETNP:
+      setnp8((addr_t *)*dst_addr, (addr_t *)&(info->ctrl_regs.rflags));
+      break;
+    case V3_OP_SETNS:
+      setns8((addr_t *)*dst_addr, (addr_t *)&(info->ctrl_regs.rflags));
+      break;
+    case V3_OP_SETNZ:
+      setnz8((addr_t *)*dst_addr, (addr_t *)&(info->ctrl_regs.rflags));
+      break;
+    case V3_OP_SETO:
+      seto8((addr_t *)*dst_addr, (addr_t *)&(info->ctrl_regs.rflags));
+      break;
+    case V3_OP_SETP:
+      setp8((addr_t *)*dst_addr, (addr_t *)&(info->ctrl_regs.rflags));
+      break;
+    case V3_OP_SETS:
+      sets8((addr_t *)*dst_addr, (addr_t *)&(info->ctrl_regs.rflags));
+      break;
+    case V3_OP_SETZ:
+      setz8((addr_t *)*dst_addr, (addr_t *)&(info->ctrl_regs.rflags));
+      break;
+
+    default:
+      PrintError("Unknown 8 bit instruction\n");
+      return -1;
+    }
+
+  } else if (dec_instr.dst_operand.size == 2) {
+
+    switch (dec_instr.op_type) {
+    case V3_OP_ADC:
+      adc16((addr_t *)*dst_addr, (addr_t *)src_addr, (addr_t *)&(info->ctrl_regs.rflags));
+      break;
+    case V3_OP_ADD:
+      add16((addr_t *)*dst_addr, (addr_t *)src_addr, (addr_t *)&(info->ctrl_regs.rflags));
+      break;
+    case V3_OP_AND:
+      and16((addr_t *)*dst_addr, (addr_t *)src_addr, (addr_t *)&(info->ctrl_regs.rflags));
+      break;
+    case V3_OP_OR:
+      or16((addr_t *)*dst_addr, (addr_t *)src_addr, (addr_t *)&(info->ctrl_regs.rflags));
+      break;
+    case V3_OP_XOR:
+      xor16((addr_t *)*dst_addr, (addr_t *)src_addr, (addr_t *)&(info->ctrl_regs.rflags));
+      break;
+    case V3_OP_SUB:
+      sub16((addr_t *)*dst_addr, (addr_t *)src_addr, (addr_t *)&(info->ctrl_regs.rflags));
+      break;
+
+
+    case V3_OP_INC:
+      inc16((addr_t *)*dst_addr, (addr_t *)&(info->ctrl_regs.rflags));
+      break;
+    case V3_OP_DEC:
+      dec16((addr_t *)*dst_addr, (addr_t *)&(info->ctrl_regs.rflags));
+      break;
+    case V3_OP_NEG:
+      neg16((addr_t *)*dst_addr, (addr_t *)&(info->ctrl_regs.rflags));
+      break;
+
+    case V3_OP_MOV:
+      mov16((addr_t *)*dst_addr, (addr_t *)src_addr);
+      break;
+    case V3_OP_NOT:
+      not16((addr_t *)*dst_addr);
+      break;
+    case V3_OP_XCHG:
+      xchg16((addr_t *)*dst_addr, (addr_t *)src_addr);
+      break;
+      
+    default:
+      PrintError("Unknown 16 bit instruction\n");
+      return -1;
+    }
+
+  } else if (dec_instr.dst_operand.size == 4) {
+
+    switch (dec_instr.op_type) {
+    case V3_OP_ADC:
+      adc32((addr_t *)*dst_addr, (addr_t *)src_addr, (addr_t *)&(info->ctrl_regs.rflags));
+      break;
+    case V3_OP_ADD:
+      add32((addr_t *)*dst_addr, (addr_t *)src_addr, (addr_t *)&(info->ctrl_regs.rflags));
+      break;
+    case V3_OP_AND:
+      and32((addr_t *)*dst_addr, (addr_t *)src_addr, (addr_t *)&(info->ctrl_regs.rflags));
+      break;
+    case V3_OP_OR:
+      or32((addr_t *)*dst_addr, (addr_t *)src_addr, (addr_t *)&(info->ctrl_regs.rflags));
+      break;
+    case V3_OP_XOR:
+      xor32((addr_t *)*dst_addr, (addr_t *)src_addr, (addr_t *)&(info->ctrl_regs.rflags));
+      break;
+    case V3_OP_SUB:
+      sub32((addr_t *)*dst_addr, (addr_t *)src_addr, (addr_t *)&(info->ctrl_regs.rflags));
+      break;
+
+    case V3_OP_INC:
+      inc32((addr_t *)*dst_addr, (addr_t *)&(info->ctrl_regs.rflags));
+      break;
+    case V3_OP_DEC:
+      dec32((addr_t *)*dst_addr, (addr_t *)&(info->ctrl_regs.rflags));
+      break;
+    case V3_OP_NEG:
+      neg32((addr_t *)*dst_addr, (addr_t *)&(info->ctrl_regs.rflags));
+      break;
+
+    case V3_OP_MOV:
+      mov32((addr_t *)*dst_addr, (addr_t *)src_addr);
+      break;
+    case V3_OP_NOT:
+      not32((addr_t *)*dst_addr);
+      break;
+    case V3_OP_XCHG:
+      xchg32((addr_t *)*dst_addr, (addr_t *)src_addr);
+      break;
+      
+    default:
+      PrintError("Unknown 32 bit instruction\n");
+      return -1;
+    }
+
+  } else if (dec_instr.dst_operand.size == 8) {
+    PrintError("64 bit instructions not handled\n");
     return -1;
-  }
-
-  if (instr_info.has_rep==1) { 
-    PrintDebug("Emulated instruction has rep\n");
-  }
-
-  /*
-  if (instr_info.has_rep == 1) {
-    PrintError("We currently don't handle rep* instructions\n");
-    V3_Free(write_op);
-    V3_Free(data_page);
+  } else {
+    PrintError("Invalid Operation Size\n");
     return -1;
   }
-  */
 
-  data_page->page_addr = get_new_page();
-  data_page->va = PAGE_ADDR(write_gva);
-  data_page->pte.present = 1;
-  data_page->pte.writable = 1;
-  data_page->pte.user_page = 1;
-  data_page->pte.page_base_addr = PAGE_BASE_ADDR((addr_t)V3_PAddr((void *)(addr_t)(data_page->page_addr)));
+  info->rip += dec_instr.instr_length;
 
-
-
-  write_op->write = write;
-  write_op->write_addr = write_gpa;
-  write_op->length = instr_info.op_size;
-  write_op->private_data = private_data;
-
-  write_op->write_data = (void *)(data_page->page_addr + data_addr_offset);
-
-  list_add(&(write_op->write_list), &(info->emulator.write_regions));
-  info->emulator.num_write_regions--;
-
-  v3_replace_shdw_page32(info, data_page->va, &(data_page->pte), &saved_pte);
-
-
-  list_add(&(data_page->page_list), &(info->emulator.emulated_pages));
-  info->emulator.num_emulated_pages++;
-
-  if (saved_pte.present == 1) {
-    struct saved_page * saved_data_page = V3_Malloc(sizeof(struct saved_page));
-    saved_data_page->pte = saved_pte;
-    saved_data_page->va = PAGE_ADDR(write_gva);
-
-    list_add(&(saved_data_page->page_list), &(info->emulator.saved_pages));
-    info->emulator.num_saved_pages++;
-  }
-
-
-  if (info->emulator.running == 0) {
-    //    setup_code_page(info, instr, &instr_info);
-    set_stepping(info);
-    info->emulator.running = 1;
-    info->run_state = VM_EMULATING;
-    info->emulator.instr_length = instr_info.instr_length;
-  }
-
-  return 0;
+  return dec_instr.dst_operand.size;
 }
 
-
-// end emulation
-int v3_emulation_exit_handler(struct guest_info * info) {
-  struct saved_page * svpg, * p_svpg;
-  struct emulated_page * empg, * p_empg;
-  struct write_region * wr_reg, * p_wr_reg;
-  pte32_t dummy_pte;
-
-  // Complete the writes
-  // delete writes
-  // swap out emulated pages with blank dummies
-  // swap in saved pages
-  // increment rip
-  
-  PrintDebug("V3 Emulation Exit Handler\n");
-
-  list_for_each_entry_safe(wr_reg, p_wr_reg, &(info->emulator.write_regions), write_list) {
-    wr_reg->write(wr_reg->write_addr, wr_reg->write_data, wr_reg->length, wr_reg->private_data);
-    PrintDebug("Writing \n");
-    
-    list_del(&(wr_reg->write_list));
-    V3_Free(wr_reg);
-
-  }
-  info->emulator.num_write_regions = 0;
-
-
-  *(uint_t *)&dummy_pte = 0;
-  
-  list_for_each_entry_safe(empg, p_empg, &(info->emulator.emulated_pages), page_list) {
-    pte32_t empte32_t;
-
-    PrintDebug("wiping page %p\n", (void *)(addr_t)(empg->va)); 
-
-    v3_replace_shdw_page32(info, empg->va, &dummy_pte, &empte32_t);
-    V3_FreePage((void *)(V3_PAddr((void *)(empg->page_addr))));
-
-    list_del(&(empg->page_list));
-    V3_Free(empg);
-  }
-  info->emulator.num_emulated_pages = 0;
-
-  list_for_each_entry_safe(svpg, p_svpg, &(info->emulator.saved_pages), page_list) {
-
-    PrintDebug("Setting Saved page %p back\n", (void *)(addr_t)(svpg->va)); 
-    v3_replace_shdw_page32(info, empg->va, &(svpg->pte), &dummy_pte);
-    
-    list_del(&(svpg->page_list));
-    V3_Free(svpg);
-  }
-  info->emulator.num_saved_pages = 0;
-
-  info->run_state = VM_RUNNING;
-  info->emulator.running = 0;
-  //info->rip += info->emulator.instr_length;
-
-
-  PrintDebug("Returning to rip: 0x%p\n", (void *)(addr_t)(info->rip));
-
-  info->emulator.instr_length = 0;
-  
-  
-  unset_stepping(info);
-
-
-  PrintDebug("returning from emulation\n");
-
-  return 0;
-}