X-Git-Url: http://v3vee.org/palacios/gitweb/gitweb.cgi?a=blobdiff_plain;f=palacios%2Fsrc%2Fpalacios%2Fvmm_ctrl_regs.c;h=894bfc2a0c7ba5dddebba72a4ea777a8b8939d1a;hb=207e3b36648e4019ad8505c75ae6ef0778464a26;hp=90a5eab88d8ae110a424d3d662c714f280a2c17a;hpb=a901a91b64a0aa5d33ecb072a826c6e2f505380d;p=palacios.git

diff --git a/palacios/src/palacios/vmm_ctrl_regs.c b/palacios/src/palacios/vmm_ctrl_regs.c
index 90a5eab..894bfc2 100644
--- a/palacios/src/palacios/vmm_ctrl_regs.c
+++ b/palacios/src/palacios/vmm_ctrl_regs.c
@@ -41,18 +41,7 @@
 
 static int handle_lmsw(struct guest_info * info, struct x86_instr * dec_instr);
 static int handle_clts(struct guest_info * info, struct x86_instr * dec_instr);
-
 static int handle_mov_to_cr0(struct guest_info * info, struct x86_instr * dec_instr);
-static int handle_mov_to_cr0_32(struct guest_info * info, struct x86_instr * dec_instr);
-static int handle_mov_to_cr0_32pae(struct guest_info * info, struct x86_instr * dec_instr);
-static int handle_mov_to_cr0_64(struct guest_info * info, struct x86_instr * dec_instr);
-static int handle_mov_to_cr0_64compat(struct guest_info * info, struct x86_instr * dec_instr);
-
-static int handle_mov_to_cr3_32(struct guest_info * info, struct x86_instr * dec_instr);
-static int handle_mov_to_cr3_32pae(struct guest_info * info, struct x86_instr * dec_instr);
-static int handle_mov_to_cr3_64(struct guest_info * info, struct x86_instr * dec_instr);
-static int handle_mov_to_cr3_64compat(struct guest_info * info, struct x86_instr * dec_instr);
-
 
 
 // First Attempt = 494 lines
@@ -68,14 +57,6 @@ int v3_handle_cr0_write(struct guest_info * info) {
     ret = read_guest_va_memory(info, get_addr_linear(info, info->rip, &(info->segments.cs)), 15, instr);
   }
 
-  /* The IFetch will already have faulted in the necessary bytes for the full instruction
-    if (ret != 15) {
-    // I think we should inject a GPF into the guest
-    PrintError("Could not read instruction (ret=%d)\n", ret);
-    return -1;
-    }
-  */
-
   if (v3_decode(info, (addr_t)instr, &dec_instr) == -1) {
     PrintError("Could not decode instruction\n");
     return -1;
@@ -112,78 +93,64 @@ int v3_handle_cr0_write(struct guest_info * info) {
 
 
 
+// The CR0 register only has flags in the low 32 bits
+// The hardware does a format check to make sure the high bits are zero
+// Because of this we can ignore the high 32 bits here
 static int handle_mov_to_cr0(struct guest_info * info, struct x86_instr * dec_instr) {
-  PrintDebug("MOV2CR0\n");
-
-  switch (info->cpu_mode) {
-  case REAL:
-  case PROTECTED:
-    return handle_mov_to_cr0_32(info, dec_instr);    
-  case PROTECTED_PAE:
-    return handle_mov_to_cr0_32pae(info, dec_instr);
-  case LONG:
-    return handle_mov_to_cr0_64(info, dec_instr);
-  case LONG_32_COMPAT:
-    return handle_mov_to_cr0_64compat(info, dec_instr);
-  default:
-    PrintError("Invalid CPU Operating Mode: %d\n", info->cpu_mode);
-    return -1;
+  // 32 bit registers
+  struct cr0_32 * shadow_cr0 = (struct cr0_32 *)&(info->ctrl_regs.cr0);
+  struct cr0_32 * new_cr0 = (struct cr0_32 *)(dec_instr->src_operand.operand);
+  struct cr0_32 * guest_cr0 = (struct cr0_32 *)&(info->shdw_pg_state.guest_cr0);
+  uint_t paging_transition = 0;
 
-  }
-}
+  PrintDebug("MOV2CR0 (MODE=%s)\n", v3_cpu_mode_to_str(info->cpu_mode));
+  
+  PrintDebug("OperandVal = %x, length=%d\n", *(uint_t *)new_cr0, dec_instr->src_operand.size);
+  
+  PrintDebug("Old CR0=%x\n", *(uint_t *)shadow_cr0);
+  PrintDebug("Old Guest CR0=%x\n", *(uint_t *)guest_cr0);	
 
-static int handle_mov_to_cr0_32pae(struct guest_info * info, struct x86_instr * dec_instr) {
-  PrintError("32 bit PAE mov to CR0 not implemented\n");
-  return -1;
-}
 
-static int handle_mov_to_cr0_64(struct guest_info * info, struct x86_instr * dec_instr) {
-  PrintError("64 bit mov to CR0 not implemented\n");
-  return -1;
-}
+  // We detect if this is a paging transition
+  if (guest_cr0->pg != new_cr0->pg) {
+    paging_transition = 1;
+  }  
 
-static int handle_mov_to_cr0_64compat(struct guest_info * info, struct x86_instr * dec_instr) {
-  PrintError("64 bit compatibility mode move to CR0 not implemented\n");
-  return -1;
-}
+  // Guest always sees the value they wrote
+  *guest_cr0 = *new_cr0;
 
+  // This value must always be set to 1 
+  guest_cr0->et = 1;    
 
-static int handle_mov_to_cr0_32(struct guest_info * info, struct x86_instr * dec_instr) {
+  // Set the shadow register to catch non-virtualized flags
+  *shadow_cr0 = *guest_cr0;
 
-  // 32 bit registers
-  struct cr0_32 *real_cr0 = (struct cr0_32*)&(info->ctrl_regs.cr0);
-  struct cr0_32 *new_cr0= (struct cr0_32 *)(dec_instr->src_operand.operand);
-  
-  PrintDebug("OperandVal = %x, length=%d\n", *(uint_t *)new_cr0, dec_instr->src_operand.size);
-  
-  
-  PrintDebug("Old CR0=%x\n", *(uint_t *)real_cr0);
-  *real_cr0 = *new_cr0;
-  
-  
-  if (info->shdw_pg_mode == SHADOW_PAGING) {
-    struct cr0_32 * shadow_cr0 = (struct cr0_32 *)&(info->shdw_pg_state.guest_cr0);
-    
-    PrintDebug("Old Shadow CR0=%x\n", *(uint_t *)shadow_cr0);	
-    
-    real_cr0->et = 1;
-    
-    *shadow_cr0 = *new_cr0;
-    shadow_cr0->et = 1;
-    
+  // Paging is always enabled
+  shadow_cr0->pg = 1;  
+
+  // Was there a paging transition
+  // Meaning we need to change the page tables
+  if (paging_transition) {
     if (v3_get_mem_mode(info) == VIRTUAL_MEM) {
-      struct cr3_32 * shadow_cr3 = (struct cr3_32 *)&(info->shdw_pg_state.shadow_cr3);
-      PrintDebug("Setting up Shadow Page Table\n");
-      info->ctrl_regs.cr3 = *(addr_t*)shadow_cr3;
+
+      PrintDebug("Activating Shadow Page Tables\n");
+      
+      if (v3_activate_shadow_pt(info) == -1) {
+	PrintError("Failed to activate shadow page tables\n");
+	return -1;
+      }
     } else  {
-      info->ctrl_regs.cr3 = *(addr_t*)&(info->direct_map_pt);
-      real_cr0->pg = 1;
+      
+      if (v3_activate_passthrough_pt(info) == -1) {
+	PrintError("Failed to activate passthrough page tables\n");
+	return -1;
+      }
     }
-    
-    PrintDebug("New Shadow CR0=%x\n",*(uint_t *)shadow_cr0);
   }
-  PrintDebug("New CR0=%x\n", *(uint_t *)real_cr0);
-  
+
+  PrintDebug("New Guest CR0=%x\n",*(uint_t *)guest_cr0);  
+  PrintDebug("New CR0=%x\n", *(uint_t *)shadow_cr0);
+
   return 0;
 }
 
@@ -192,21 +159,21 @@ static int handle_mov_to_cr0_32(struct guest_info * info, struct x86_instr * dec
 
 static int handle_clts(struct guest_info * info, struct x86_instr * dec_instr) {
   // CLTS
-  struct cr0_32 *real_cr0 = (struct cr0_32*)&(info->ctrl_regs.cr0);
+  struct cr0_32 * real_cr0 = (struct cr0_32*)&(info->ctrl_regs.cr0);
   
   real_cr0->ts = 0;
   
   if (info->shdw_pg_mode == SHADOW_PAGING) {
-    struct cr0_32 * shadow_cr0 = (struct cr0_32 *)&(info->shdw_pg_state.guest_cr0);
-    shadow_cr0->ts = 0;
+    struct cr0_32 * guest_cr0 = (struct cr0_32 *)&(info->shdw_pg_state.guest_cr0);
+    guest_cr0->ts = 0;
   }
   return 0;
 }
 
 
 static int handle_lmsw(struct guest_info * info, struct x86_instr * dec_instr) {
- struct cr0_real *real_cr0  = (struct cr0_real*)&(info->ctrl_regs.cr0);
- struct cr0_real *new_cr0 = (struct cr0_real *)(dec_instr->src_operand.operand);	
+ struct cr0_real * real_cr0  = (struct cr0_real*)&(info->ctrl_regs.cr0);
+ struct cr0_real * new_cr0 = (struct cr0_real *)(dec_instr->src_operand.operand);	
  uchar_t new_cr0_val;
  
  PrintDebug("LMSW\n");
@@ -215,19 +182,22 @@ static int handle_lmsw(struct guest_info * info, struct x86_instr * dec_instr) {
  
  PrintDebug("OperandVal = %x\n", new_cr0_val);
  
+ // We can just copy the new value through
+ // we don't need to virtualize the lower 4 bits
  PrintDebug("Old CR0=%x\n", *(uint_t *)real_cr0);	
  *(uchar_t*)real_cr0 &= 0xf0;
  *(uchar_t*)real_cr0 |= new_cr0_val;
  PrintDebug("New CR0=%x\n", *(uint_t *)real_cr0);	
  
  
+ // If Shadow paging is enabled we push the changes to the virtualized copy of cr0
  if (info->shdw_pg_mode == SHADOW_PAGING) {
-   struct cr0_real * shadow_cr0 = (struct cr0_real*)&(info->shdw_pg_state.guest_cr0);
+   struct cr0_real * guest_cr0 = (struct cr0_real*)&(info->shdw_pg_state.guest_cr0);
    
-   PrintDebug(" Old Shadow CR0=%x\n", *(uint_t *)shadow_cr0);	
-   *(uchar_t*)shadow_cr0 &= 0xf0;
-   *(uchar_t*)shadow_cr0 |= new_cr0_val;
-   PrintDebug("New Shadow CR0=%x\n", *(uint_t *)shadow_cr0);	
+   PrintDebug("Old Guest CR0=%x\n", *(uint_t *)guest_cr0);	
+   *(uchar_t*)guest_cr0 &= 0xf0;
+   *(uchar_t*)guest_cr0 |= new_cr0_val;
+   PrintDebug("New Guest CR0=%x\n", *(uint_t *)guest_cr0);	
  }
  return 0;
 }
@@ -236,11 +206,6 @@ static int handle_lmsw(struct guest_info * info, struct x86_instr * dec_instr) {
 
 
 
-
-
-
-
-
 // First attempt = 253 lines
 // current = 51 lines
 int v3_handle_cr0_read(struct guest_info * info) {
@@ -254,13 +219,6 @@ int v3_handle_cr0_read(struct guest_info * info) {
     ret = read_guest_va_memory(info, get_addr_linear(info, info->rip, &(info->segments.cs)), 15, instr);
   }
 
-  /* The IFetch will already have faulted in the necessary bytes for the full instruction
-     if (ret != 15) {
-     // I think we should inject a GPF into the guest
-     PrintError("Could not read instruction (ret=%d)\n", ret);
-     return -1;
-     }
-  */
 
   if (v3_decode(info, (addr_t)instr, &dec_instr) == -1) {
     PrintError("Could not decode instruction\n");
@@ -268,31 +226,31 @@ int v3_handle_cr0_read(struct guest_info * info) {
   }
   
   if (v3_opcode_cmp(V3_OPCODE_MOVCR2, (const uchar_t *)(dec_instr.opcode)) == 0) {
-    struct cr0_32 * virt_cr0 = (struct cr0_32 *)(dec_instr.dst_operand.operand);
-    struct cr0_32 * real_cr0 = (struct cr0_32 *)&(info->ctrl_regs.cr0);
-    
-    PrintDebug("MOVCR2\n");
-    PrintDebug("CR0 at 0x%p\n", (void *)real_cr0);
+    struct cr0_32 * dst_reg = (struct cr0_32 *)(dec_instr.dst_operand.operand);
+    struct cr0_32 * shadow_cr0 = (struct cr0_32 *)&(info->ctrl_regs.cr0);
+
+    PrintDebug("MOVCR2 (mode=%s)\n", info->cpu_mode);
 
     if (info->shdw_pg_mode == SHADOW_PAGING) {
-      *virt_cr0 = *(struct cr0_32 *)&(info->shdw_pg_state.guest_cr0);
+      struct cr0_32 * guest_cr0 = (struct cr0_32 *)&(info->shdw_pg_state.guest_cr0);
+      *dst_reg = *guest_cr0;
     } else {
-      *virt_cr0 = *real_cr0;
+      *dst_reg = *shadow_cr0;
     }
-    
-    PrintDebug("real CR0: %x\n", *(uint_t*)real_cr0);
-    PrintDebug("returned CR0: %x\n", *(uint_t*)virt_cr0);
+
+    PrintDebug("Shadow CR0: %x\n", *(uint_t*)shadow_cr0);    
+    PrintDebug("returned CR0: %x\n", *(uint_t*)dst_reg);
   } else if (v3_opcode_cmp(V3_OPCODE_SMSW, (const uchar_t *)(dec_instr.opcode)) == 0) {
-    struct cr0_real *real_cr0= (struct cr0_real*)&(info->ctrl_regs.cr0);
-    struct cr0_real *virt_cr0 = (struct cr0_real *)(dec_instr.dst_operand.operand);
-    char cr0_val = *(char*)real_cr0 & 0x0f;
+    struct cr0_real * shadow_cr0 = (struct cr0_real *)&(info->ctrl_regs.cr0);
+    struct cr0_real * dst_reg = (struct cr0_real *)(dec_instr.dst_operand.operand);
+    char cr0_val = *(char*)shadow_cr0 & 0x0f;
     
     PrintDebug("SMSW\n");
 
-    PrintDebug("CR0 at 0x%p\n", real_cr0);
-
-    *(char *)virt_cr0 &= 0xf0;
-    *(char *)virt_cr0 |= cr0_val;
+    // The lower 4 bits of the guest/shadow CR0 are mapped through
+    // We can treat nested and shadow paging the same here
+    *(char *)dst_reg &= 0xf0;
+    *(char *)dst_reg |= cr0_val;
     
   } else {
     PrintError("Unhandled opcode in handle_cr0_read\n");
@@ -326,11 +284,15 @@ int v3_handle_cr3_write(struct guest_info * info) {
   }
 
   if (v3_opcode_cmp(V3_OPCODE_MOV2CR, (const uchar_t *)(dec_instr.opcode)) == 0) {
-    PrintDebug("MOV2CR3\n");
-
-    if (info->mem_mode == PHYSICAL_MEM) {
-      // All we do is update the guest CR3
+    PrintDebug("MOV2CR3 (cpu_mode=%s)\n", v3_cpu_mode_to_str(info->cpu_mode));
 
+    if (info->shdw_pg_mode == SHADOW_PAGING) {
+      PrintDebug("Old Shadow CR3=%p; Old Guest CR3=%p\n", 
+		 (void *)(addr_t)(info->ctrl_regs.cr3), 
+		 (void*)(addr_t)(info->shdw_pg_state.guest_cr3));
+      
+    
+      // We update the guest CR3    
       if (info->cpu_mode == LONG) {
 	struct cr3_64 * new_cr3 = (struct cr3_64 *)(dec_instr.src_operand.operand);
 	struct cr3_64 * guest_cr3 = (struct cr3_64 *)&(info->shdw_pg_state.guest_cr3);
@@ -340,30 +302,32 @@ int v3_handle_cr3_write(struct guest_info * info) {
 	struct cr3_32 * guest_cr3 = (struct cr3_32 *)&(info->shdw_pg_state.guest_cr3);
 	*guest_cr3 = *new_cr3;
       }
-
-    } else {
-
-      switch (info->cpu_mode) {
-      case PROTECTED:
-	if (handle_mov_to_cr3_32(info, &dec_instr) == -1) {
-	  return -1;
-	}
-      case PROTECTED_PAE:
-	if (handle_mov_to_cr3_32pae(info, &dec_instr) == -1) {
-	  return -1;
-	}
-      case LONG:
-	if (handle_mov_to_cr3_64(info, &dec_instr) == -1) {
-	  return -1;
-	}
-      case LONG_32_COMPAT:
-	if (handle_mov_to_cr3_64compat(info, &dec_instr) == -1) {
+      
+      // If Paging is enabled in the guest then we need to change the shadow page tables
+      if (info->mem_mode == VIRTUAL_MEM) {
+	if (v3_activate_shadow_pt(info) == -1) {
+	  PrintError("Failed to activate 32 bit shadow page table\n");
 	  return -1;
 	}
-      default:
-	PrintError("Unhandled CPU mode: %d\n", info->cpu_mode);
-	return -1;
+      } 
+ 
+      PrintDebug("New Shadow CR3=%p; New Guest CR3=%p\n", 
+		 (void *)(addr_t)(info->ctrl_regs.cr3), 
+		 (void*)(addr_t)(info->shdw_pg_state.guest_cr3));
+      
+    } else if (info->shdw_pg_mode == NESTED_PAGING) {
+ 
+     // This is just a passthrough operation which we probably don't need here
+      if (info->cpu_mode == LONG) {
+	struct cr3_64 * new_cr3 = (struct cr3_64 *)(dec_instr.src_operand.operand);
+	struct cr3_64 * guest_cr3 = (struct cr3_64 *)&(info->ctrl_regs.cr3);
+	*guest_cr3 = *new_cr3;
+      } else {
+	struct cr3_32 * new_cr3 = (struct cr3_32 *)(dec_instr.src_operand.operand);
+	struct cr3_32 * guest_cr3 = (struct cr3_32 *)&(info->ctrl_regs.cr3);
+	*guest_cr3 = *new_cr3;
       }
+
     }
   } else {
     PrintError("Unhandled opcode in handle_cr3_write\n");
@@ -377,85 +341,6 @@ int v3_handle_cr3_write(struct guest_info * info) {
 
 
 
-
-
-
-
-static int handle_mov_to_cr3_32(struct guest_info * info, struct x86_instr * dec_instr) {
-  PrintDebug("CR3 at 0x%p\n", &(info->ctrl_regs.cr3));
-
-  if (info->shdw_pg_mode == SHADOW_PAGING) {
-    struct cr3_32 * new_cr3 = (struct cr3_32 *)(dec_instr->src_operand.operand);	
-    struct cr3_32 * guest_cr3 = (struct cr3_32 *)&(info->shdw_pg_state.guest_cr3);
-    struct cr3_32 * shadow_cr3 = (struct cr3_32 *)&(info->shdw_pg_state.shadow_cr3);
-    int cached = 0;
-    
-    
-    PrintDebug("Old Shadow CR3=%x; Old Guest CR3=%x\n", 
-	       *(uint_t*)shadow_cr3, *(uint_t*)guest_cr3);
-    
-    
-    
-    cached = v3_cache_page_tables32(info, (addr_t)V3_PAddr((void *)(addr_t)CR3_TO_PDE32((void *)*(addr_t *)new_cr3)));
-    
-    if (cached == -1) {
-      PrintError("CR3 Cache failed\n");
-      return -1;
-    } else if (cached == 0) {
-      addr_t shadow_pt;
-      
-      if(info->mem_mode == VIRTUAL_MEM) {
-	PrintDebug("New CR3 is different - flushing shadow page table %p\n", shadow_cr3 );
-	delete_page_tables_32((pde32_t *)CR3_TO_PDE32(*(uint_t*)shadow_cr3));
-      }
-      
-      shadow_pt =  v3_create_new_shadow_pt();
-      
-      shadow_cr3->pdt_base_addr = (addr_t)V3_PAddr((void *)(addr_t)PD32_BASE_ADDR(shadow_pt));
-      PrintDebug( "Created new shadow page table %p\n", (void *)(addr_t)shadow_cr3->pdt_base_addr );
-      //PrintDebugPageTables( (pde32_t *)CR3_TO_PDE32(*(uint_t*)shadow_cr3) );
-      
-      
-    } else {
-      PrintDebug("Reusing cached shadow Page table\n");
-    }
-    
-    
-    shadow_cr3->pwt = new_cr3->pwt;
-    shadow_cr3->pcd = new_cr3->pcd;
-    
-    // What the hell...
-    *guest_cr3 = *new_cr3;
-    
-    PrintDebug("New Shadow CR3=%x; New Guest CR3=%x\n", 
-	       *(uint_t*)shadow_cr3, *(uint_t*)guest_cr3);
-    
-    if (info->mem_mode == VIRTUAL_MEM) {
-      // If we aren't in paged mode then we have to preserve the identity mapped CR3
-      info->ctrl_regs.cr3 = *(addr_t*)shadow_cr3;
-    }
-  }
-  return 0;
-}
-
-
-static int handle_mov_to_cr3_32pae(struct guest_info * info, struct x86_instr * dec_instr) {
-  PrintError("32 Bit PAE mode Mov to CR3 not implemented\n");
-  return -1;
-}
-
-static int handle_mov_to_cr3_64(struct guest_info * info, struct x86_instr * dec_instr) {
-  PrintError("Long mode Mov to CR3 not implemented\n");
-  return -1;
-}
-
-static int handle_mov_to_cr3_64compat(struct guest_info * info, struct x86_instr * dec_instr) {
-  PrintError("Long compatiblity mode move to CR3 not implemented\n");
-  return -1;
-}
-
-
-
 // first attempt = 156 lines
 // current = 36 lines
 int v3_handle_cr3_read(struct guest_info * info) {
@@ -469,30 +354,40 @@ int v3_handle_cr3_read(struct guest_info * info) {
     ret = read_guest_va_memory(info, get_addr_linear(info, info->rip, &(info->segments.cs)), 15, instr);
   }
 
-  /* The IFetch will already have faulted in the necessary bytes for the full instruction
-     if (ret != 15) {
-     // I think we should inject a GPF into the guest
-     PrintError("Could not read instruction (ret=%d)\n", ret);
-     return -1;
-     }
-  */
-
   if (v3_decode(info, (addr_t)instr, &dec_instr) == -1) {
     PrintError("Could not decode instruction\n");
     return -1;
   }
 
   if (v3_opcode_cmp(V3_OPCODE_MOVCR2, (const uchar_t *)(dec_instr.opcode)) == 0) {
-    PrintDebug("MOVCR32\n");
-    struct cr3_32 * virt_cr3 = (struct cr3_32 *)(dec_instr.dst_operand.operand);
-
-    PrintDebug("CR3 at 0x%p\n", &(info->ctrl_regs.cr3));
+    PrintDebug("MOVCR32 (mode=%s)\n", v3_cpu_mode_to_str(info->cpu_mode));
 
     if (info->shdw_pg_mode == SHADOW_PAGING) {
-      *virt_cr3 = *(struct cr3_32 *)&(info->shdw_pg_state.guest_cr3);
-    } else {
-      *virt_cr3 = *(struct cr3_32 *)&(info->ctrl_regs.cr3);
+
+      if (info->cpu_mode == LONG) {
+	struct cr3_64 * dst_reg = (struct cr3_64 *)(dec_instr.dst_operand.operand);
+	struct cr3_64 * guest_cr3 = (struct cr3_64 *)&(info->shdw_pg_state.guest_cr3);
+	*dst_reg = *guest_cr3;
+      } else {
+	struct cr3_32 * dst_reg = (struct cr3_32 *)(dec_instr.dst_operand.operand);
+	struct cr3_32 * guest_cr3 = (struct cr3_32 *)&(info->shdw_pg_state.guest_cr3);
+	*dst_reg = *guest_cr3;
+      }
+
+    } else if (info->shdw_pg_mode == NESTED_PAGING) {
+
+      // This is just a passthrough operation which we probably don't need here
+      if (info->cpu_mode == LONG) {
+	struct cr3_64 * dst_reg = (struct cr3_64 *)(dec_instr.dst_operand.operand);
+	struct cr3_64 * guest_cr3 = (struct cr3_64 *)&(info->ctrl_regs.cr3);
+	*dst_reg = *guest_cr3;
+      } else {
+	struct cr3_32 * dst_reg = (struct cr3_32 *)(dec_instr.dst_operand.operand);
+	struct cr3_32 * guest_cr3 = (struct cr3_32 *)&(info->ctrl_regs.cr3);
+	*dst_reg = *guest_cr3;
+      }
     }
+
   } else {
     PrintError("Unhandled opcode in handle_cr3_read\n");
     return -1;
@@ -503,9 +398,12 @@ int v3_handle_cr3_read(struct guest_info * info) {
   return 0;
 }
 
+
+// We don't need to virtualize CR4, all we need is to detect the activation of PAE
 int v3_handle_cr4_read(struct guest_info * info) {
-  PrintError("CR4 Read not handled\n");
-  return -1;
+  //  PrintError("CR4 Read not handled\n");
+  // Do nothing...
+  return 0;
 }
 
 int v3_handle_cr4_write(struct guest_info * info) {
@@ -531,18 +429,15 @@ int v3_handle_cr4_write(struct guest_info * info) {
 
   if ((info->cpu_mode == PROTECTED) || (info->cpu_mode == PROTECTED_PAE)) {
     struct cr4_32 * new_cr4 = (struct cr4_32 *)(dec_instr.src_operand.operand);
-    struct cr4_32 * old_cr4 = (struct cr4_32 *)&(info->ctrl_regs.cr4);
+    struct cr4_32 * cr4 = (struct cr4_32 *)&(info->ctrl_regs.cr4);
     
     PrintDebug("OperandVal = %x, length = %d\n", *(uint_t *)new_cr4, dec_instr.src_operand.size);
-    PrintDebug("Old CR4=%x\n", *(uint_t *)old_cr4);
-
-
-
+    PrintDebug("Old CR4=%x\n", *(uint_t *)cr4);
 
     if ((info->shdw_pg_mode == SHADOW_PAGING) && 
 	(v3_get_mem_mode(info) == PHYSICAL_MEM)) {
 
-      if ((old_cr4->pae == 0) && (new_cr4->pae == 1)) {
+      if ((cr4->pae == 0) && (new_cr4->pae == 1)) {
 	PrintDebug("Creating PAE passthrough tables\n");
 
 	// Delete the old 32 bit direct map page tables
@@ -554,16 +449,17 @@ int v3_handle_cr4_write(struct guest_info * info) {
 	// reset cr3 to new page tables
 	info->ctrl_regs.cr3 = *(addr_t*)&(info->direct_map_pt);
 
-      } else if ((old_cr4->pae == 1) && (new_cr4->pae == 0)) {
+      } else if ((cr4->pae == 1) && (new_cr4->pae == 0)) {
 	// Create passthrough standard 32bit pagetables
 	return -1;
       }
     }
 
-    *old_cr4 = *new_cr4;
-    PrintDebug("New CR4=%x\n", *(uint_t *)old_cr4);
+    *cr4 = *new_cr4;
+    PrintDebug("New CR4=%x\n", *(uint_t *)cr4);
 
   } else {
+    PrintError("CR4 write not supported in CPU_MODE: %d\n", info->cpu_mode);
     return -1;
   }
 
@@ -586,18 +482,20 @@ int v3_handle_efer_read(uint_t msr, struct v3_msr * dst, void * priv_data) {
 int v3_handle_efer_write(uint_t msr, struct v3_msr src, void * priv_data) {
   struct guest_info * info = (struct guest_info *)(priv_data);
   struct efer_64 * new_efer = (struct efer_64 *)&(src.value);
-  struct efer_64 * old_efer = (struct efer_64 *)&(info->ctrl_regs.efer);
+  struct efer_64 * shadow_efer = (struct efer_64 *)&(info->ctrl_regs.efer);
+  struct v3_msr * guest_efer = &(info->guest_efer);
 
   PrintDebug("EFER Write\n");
-  PrintDebug("Old EFER=%p\n", (void *)*(addr_t*)(old_efer));
+  PrintDebug("Old EFER=%p\n", (void *)*(addr_t*)(shadow_efer));
 
   // We virtualize the guests efer to hide the SVME and LMA bits
-  info->guest_efer.value = src.value;
+  guest_efer->value = src.value;
 
+ 
   if ((info->shdw_pg_mode == SHADOW_PAGING) && 
       (v3_get_mem_mode(info) == PHYSICAL_MEM)) {
     
-    if ((old_efer->lme == 0) && (new_efer->lme == 1)) {
+    if ((shadow_efer->lme == 0) && (new_efer->lme == 1)) {
       PrintDebug("Transition to longmode\n");
       PrintDebug("Creating Passthrough 64 bit page tables\n");
       
@@ -616,11 +514,11 @@ int v3_handle_efer_write(uint_t msr, struct v3_msr src, void * priv_data) {
       // reset cr3 to new page tables
       info->ctrl_regs.cr3 = *(addr_t*)&(info->direct_map_pt);
       
-
-      // Does this mean we will have to fully virtualize a shadow  EFER?? (yes it does)
+      // We mark the Long Mode active  because we have paging enabled
+      // We do this in new_efer because we copy the msr in full below
       new_efer->lma = 1;
       
-    } else if ((old_efer->lme == 1) && (new_efer->lme == 0)) {
+    } else if ((shadow_efer->lme == 1) && (new_efer->lme == 0)) {
       // transition out of long mode
       //((struct efer_64 *)&(info->guest_efer.value))->lme = 0;
       //((struct efer_64 *)&(info->guest_efer.value))->lma = 0;
@@ -628,9 +526,16 @@ int v3_handle_efer_write(uint_t msr, struct v3_msr src, void * priv_data) {
       return -1;
     }
 
-    *old_efer = *new_efer;
-    PrintDebug("New EFER=%p\n", (void *)*(addr_t *)(old_efer));
+    // accept all changes to the efer, but make sure that the SVME bit is set... (SVM specific)
+    *shadow_efer = *new_efer;
+    shadow_efer->svme = 1;
+    
+
+
+    PrintDebug("New EFER=%p\n", (void *)*(addr_t *)(shadow_efer));
   } else {
+    PrintError("Write to EFER in NESTED_PAGING or VIRTUAL_MEM mode not supported\n");
+    // Should probably just check for a long mode transition, and bomb out if it is
     return -1;
   }