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.


Refactoring and additions to direct paging (nested and passthrough)
[palacios.git] / palacios / src / palacios / vmm_shadow_paging.c
index 6a0b3be..10ed641 100644 (file)
 
 #include <palacios/vmm_hashtable.h>
 
-#ifndef DEBUG_SHADOW_PAGING
+#include <palacios/vmm_direct_paging.h>
+
+
+
+
+#ifdef V3_CONFIG_SHADOW_PAGING_TELEMETRY
+#include <palacios/vmm_telemetry.h>
+#endif
+
+#ifdef V3_CONFIG_SYMBIOTIC_SWAP
+#include <palacios/vmm_sym_swap.h>
+#endif
+
+#ifndef V3_CONFIG_DEBUG_SHADOW_PAGING
 #undef PrintDebug
 #define PrintDebug(fmt, args...)
 #endif
 
 
-/*** 
- ***  There be dragons
- ***/
+static const char default_strategy[] = "VTLB";
 
 
-struct guest_table {
-  addr_t cr3;
-  struct list_head link;
-};
+static struct hashtable * master_shdw_pg_table = NULL;
+
 
+struct event_callback {
+    int (*callback)(struct guest_info *core, struct v3_shdw_pg_event *event, void *priv_data);
+    void *priv_data;
 
-struct backptr {
-  addr_t ptr;
-  struct list_head link;
+    struct list_head node;
 };
 
+static uint_t shdw_pg_hash_fn(addr_t key) {
+    char * name = (char *)key;
+    return v3_hash_buffer((uint8_t *)name, strlen(name));
+}
 
-struct shadow_page_data {
-  addr_t ptr;
-  addr_t guest_addr; 
+static int shdw_pg_eq_fn(addr_t key1, addr_t key2) {
+    char * name1 = (char *)key1;
+    char * name2 = (char *)key2;
 
-  struct list_head backptrs;
-  struct list_head guest_tables;
-};
+    return (strcmp(name1, name2) == 0);
+}
+
+static int have_callbacks(struct guest_info *core)
+{
+    return !list_empty(&(core->vm_info->shdw_impl.event_callback_list));
+}
+
+static void dispatch_event(struct guest_info *core, struct v3_shdw_pg_event *event)
+{
+    struct event_callback *cb,*temp;
+    
+    list_for_each_entry_safe(cb,
+                            temp,
+                            &(core->vm_info->shdw_impl.event_callback_list),
+                            node) {
+       cb->callback(core,event,cb->priv_data);
+    }
+}
 
 
+int V3_init_shdw_paging() {
+    extern struct v3_shdw_pg_impl * __start__v3_shdw_pg_impls[];
+    extern struct v3_shdw_pg_impl * __stop__v3_shdw_pg_impls[];
+    struct v3_shdw_pg_impl ** tmp_impl = __start__v3_shdw_pg_impls;
+    int i = 0;
 
+    master_shdw_pg_table = v3_create_htable(0, shdw_pg_hash_fn, shdw_pg_eq_fn);
 
-//DEFINE_HASHTABLE_INSERT(add_cr3_to_cache, addr_t, struct hashtable *);
-//DEFINE_HASHTABLE_SEARCH(find_cr3_in_cache, addr_t, struct hashtable *);
-//DEFINE_HASHTABLE_REMOVE(del_cr3_from_cache, addr_t, struct hashtable *, 0);
 
+    while (tmp_impl != __stop__v3_shdw_pg_impls) {
+       V3_Print(VM_NONE, VCORE_NONE, "Registering Shadow Paging Impl (%s)\n", (*tmp_impl)->name);
 
-DEFINE_HASHTABLE_INSERT(add_pte_map, addr_t, addr_t);
-DEFINE_HASHTABLE_SEARCH(find_pte_map, addr_t, addr_t);
-//DEFINE_HASHTABLE_REMOVE(del_pte_map, addr_t, addr_t, 0);
+       if (v3_htable_search(master_shdw_pg_table, (addr_t)((*tmp_impl)->name))) {
+           PrintError(VM_NONE, VCORE_NONE, "Multiple instances of shadow paging impl (%s)\n", (*tmp_impl)->name);
+           return -1;
+       }
 
+       if (v3_htable_insert(master_shdw_pg_table, 
+                            (addr_t)((*tmp_impl)->name),
+                            (addr_t)(*tmp_impl)) == 0) {
+           PrintError(VM_NONE, VCORE_NONE, "Could not register shadow paging impl (%s)\n", (*tmp_impl)->name);
+           return -1;
+       }
 
+       tmp_impl = &(__start__v3_shdw_pg_impls[++i]);
+    }
 
-static uint_t pte_hash_fn(addr_t key) {
-  return hash_long(key, 32);
+    return 0;
 }
 
-static int pte_equals(addr_t key1, addr_t key2) {
-  return (key1 == key2);
+int V3_deinit_shdw_paging() {
+    v3_free_htable(master_shdw_pg_table, 0, 0);
+    return 0;
 }
 
-static addr_t create_new_shadow_pt();
-static void inject_guest_pf(struct guest_info * info, addr_t fault_addr, pf_error_t error_code);
-static int is_guest_pf(pt_access_status_t guest_access, pt_access_status_t shadow_access);
 
 
-#include "vmm_shadow_paging_32.h"
-#include "vmm_shadow_paging_32pae.h"
-#include "vmm_shadow_paging_64.h"
+/*** 
+ ***  There be dragons
+ ***/
+
+
+#ifdef V3_CONFIG_SHADOW_PAGING_TELEMETRY
+static void telemetry_cb(struct v3_vm_info * vm, void * private_data, char * hdr) {
+    int i = 0;
+    for (i = 0; i < vm->num_cores; i++) {
+       struct guest_info * core = &(vm->cores[i]);
+
+       V3_Print(vm, core, "%s Guest Page faults: %d\n", hdr, core->shdw_pg_state.guest_faults);
+    }
+}
+#endif
 
 
 
-int v3_init_shadow_page_state(struct guest_info * info) {
-  struct shadow_page_state * state = &(info->shdw_pg_state);
+int v3_init_shdw_pg_state(struct guest_info * core) {
+    struct v3_shdw_pg_state * state = &(core->shdw_pg_state);
+    struct v3_shdw_pg_impl * impl = core->vm_info->shdw_impl.current_impl;
   
-  state->guest_cr3 = 0;
-  state->guest_cr0 = 0;
 
-  state->cached_ptes = NULL;
+    state->guest_cr3 = 0;
+    state->guest_cr0 = 0;
+    state->guest_efer.value = 0x0LL;
 
-  return 0;
-}
+    if (impl->local_init(core) == -1) {
+       PrintError(core->vm_info, core, "Error in Shadow paging local initialization (%s)\n", impl->name);
+       return -1;
+    }
 
 
+#ifdef V3_CONFIG_SHADOW_PAGING_TELEMETRY
+    v3_add_telemetry_cb(core->vm_info, telemetry_cb, NULL);
+#endif
+  
 
+    return 0;
+}
 
 
+int v3_deinit_shdw_pg_state(struct guest_info * core) {
+    struct v3_shdw_pg_impl * impl = NULL;
 
+    if (!core || !core->vm_info) {
+        return -1;
+    }
+
+    impl = core->vm_info->shdw_impl.current_impl;
+
+    if (impl && impl->local_deinit(core) == -1) {
+       PrintError(core->vm_info, core, "Error deinitializing shadow paging state\n");
+       return -1;
+    }
 
-// Reads the guest CR3 register
-// creates new shadow page tables
-// updates the shadow CR3 register to point to the new pts
-int v3_activate_shadow_pt(struct guest_info * info) {
-  switch (info->cpu_mode) {
-
-  case PROTECTED:
-    return activate_shadow_pt_32(info);
-  case PROTECTED_PAE:
-    return activate_shadow_pt_32pae(info);
-  case LONG:
-  case LONG_32_COMPAT:
-  case LONG_16_COMPAT:
-    return activate_shadow_pt_64(info);
-  default:
-    PrintError("Invalid CPU mode: %d\n", info->cpu_mode);
-    return -1;
-  }
 
-  return 0;
+    return 0;
 }
 
 
-int v3_activate_passthrough_pt(struct guest_info * info) {
-  // For now... But we need to change this....
-  // As soon as shadow paging becomes active the passthrough tables are hosed
-  // So this will cause chaos if it is called at that time
 
-  info->ctrl_regs.cr3 = *(addr_t*)&(info->direct_map_pt);
-  //PrintError("Activate Passthrough Page tables not implemented\n");
-  return 0;
-}
+int v3_init_shdw_impl(struct v3_vm_info * vm) {
+    struct v3_shdw_impl_state * impl_state = &(vm->shdw_impl);
+    v3_cfg_tree_t * pg_cfg = v3_cfg_subtree(vm->cfg_data->cfg, "paging");
+    char * pg_mode = v3_cfg_val(pg_cfg, "mode");
+    char * pg_strat = v3_cfg_val(pg_cfg, "strategy");
+    struct v3_shdw_pg_impl * impl = NULL;
+   
+    PrintDebug(vm, VCORE_NONE, "Checking if shadow paging requested.\n");
+    if (pg_mode == NULL) { 
+       V3_Print(vm, VCORE_NONE, "No paging mode specified, assuming shadow with defaults\n");
+       pg_mode = "shadow";
+    } else {
+       if (strcasecmp(pg_mode, "nested") == 0) {
+           // this check is repeated here (compare to vmm_config's determine paging mode) since
+           // shadow paging initialization *precedes* per-core pre-config.
+           extern v3_cpu_arch_t v3_mach_type;
+           if ((v3_mach_type == V3_SVM_REV3_CPU) || 
+               (v3_mach_type == V3_VMX_EPT_CPU) ||
+               (v3_mach_type == V3_VMX_EPT_UG_CPU)) {
+               PrintDebug(vm, VCORE_NONE, "Nested paging specified on machine that supports it - not initializing shadow paging\n");
+               return 0;
+           } else {
+               V3_Print(vm, VCORE_NONE, "Nested paging specified but machine does not support it - falling back to shadow paging with defaults\n");
+               pg_mode = "shadow";
+           }
+       } else if (strcasecmp(pg_mode, "shadow") != 0) { 
+           V3_Print(vm, VCORE_NONE, "Unknown paging mode '%s' specified - falling back to shadow paging with defaults\n",pg_mode);
+           pg_mode = "shadow";
+       }
+    }
 
+    if (pg_strat == NULL) {
+       pg_strat = (char *)default_strategy;
+    }
+       
+    V3_Print(vm, VCORE_NONE,"Initialization of Shadow Paging implementation\n");
 
+    impl = (struct v3_shdw_pg_impl *)v3_htable_search(master_shdw_pg_table, (addr_t)pg_strat);
 
-int v3_handle_shadow_pagefault(struct guest_info * info, addr_t fault_addr, pf_error_t error_code) {
-  
-  if (info->mem_mode == PHYSICAL_MEM) {
-    // If paging is not turned on we need to handle the special cases
+    if (impl == NULL) {
+       PrintError(vm, VCORE_NONE, "Could not find shadow paging impl (%s)\n", pg_strat);
+       return -1;
+    }
 
-#ifdef DEBUG_SHADOW_PAGING
-    PrintHostPageTree(info->cpu_mode, fault_addr, info->ctrl_regs.cr3);
-    PrintGuestPageTree(info, fault_addr, info->shdw_pg_state.guest_cr3);
-#endif
+    INIT_LIST_HEAD(&(impl_state->event_callback_list));
+   
+    impl_state->current_impl = impl;
 
-    return handle_special_page_fault(info, fault_addr, fault_addr, error_code);
-  } else if (info->mem_mode == VIRTUAL_MEM) {
-
-    switch (info->cpu_mode) {
-    case PROTECTED:
-      return handle_shadow_pagefault_32(info, fault_addr, error_code);
-      break;
-    case PROTECTED_PAE:
-      return handle_shadow_pagefault_32pae(info, fault_addr, error_code);
-    case LONG:
-      return handle_shadow_pagefault_64(info, fault_addr, error_code);
-      break;
-    default:
-      PrintError("Unhandled CPU Mode\n");
-      return -1;
+    if (impl->init(vm, pg_cfg) == -1) {
+       PrintError(vm, VCORE_NONE, "Could not initialize Shadow paging implemenation (%s)\n", impl->name);
+       return -1;
     }
-  } else {
-    PrintError("Invalid Memory mode\n");
-    return -1;
-  }
+
+
+
+    return 0;
 }
 
+int v3_deinit_shdw_impl(struct v3_vm_info * vm) {
+    struct v3_shdw_pg_impl * impl = vm->shdw_impl.current_impl;
+    struct event_callback *cb,*temp;
 
+    if (impl == NULL) {
+       // Shadow paging not implemented
+       return 0;
+    }
 
-static addr_t create_new_shadow_pt() {
-  void * host_pde = 0;
+    if (impl->deinit(vm) == -1) {
+       PrintError(vm, VCORE_NONE,"Error deinitializing shadow paging implementation\n");
+       return -1;
+    }
 
-  host_pde = V3_VAddr(V3_AllocPages(1));
-  memset(host_pde, 0, PAGE_SIZE);
+    list_for_each_entry_safe(cb,
+                            temp,
+                            &(vm->shdw_impl.event_callback_list),
+                            node) {
+       list_del(&(cb->node));
+       V3_Free(cb);
+    }
 
-  return (addr_t)host_pde;
+    return 0;
+}
+
+
+// Reads the guest CR3 register
+// creates new shadow page tables
+// updates the shadow CR3 register to point to the new pts
+int v3_activate_shadow_pt(struct guest_info * core) {
+    struct v3_shdw_impl_state * state = &(core->vm_info->shdw_impl);
+    struct v3_shdw_pg_impl * impl = state->current_impl;
+    
+    if (!have_callbacks(core)) { 
+       return impl->activate_shdw_pt(core);
+    } else {
+       int rc;
+       struct v3_shdw_pg_event event_pre={SHADOW_ACTIVATE,SHADOW_PREIMPL,0,{0,0,0,0,0,0}};
+       struct v3_shdw_pg_event event_post={SHADOW_ACTIVATE,SHADOW_POSTIMPL,0,{0,0,0,0,0,0}};
+       
+       dispatch_event(core,&event_pre);
+
+       rc =impl->activate_shdw_pt(core);
+
+       dispatch_event(core,&event_post);
+       
+       return rc;
+    }
 }
 
 
-static void inject_guest_pf(struct guest_info * info, addr_t fault_addr, pf_error_t error_code) {
-  if (info->enable_profiler) {
-    info->profiler.guest_pf_cnt++;
-  }
 
-  info->ctrl_regs.cr2 = fault_addr;
-  v3_raise_exception_with_error(info, PF_EXCEPTION, *(uint_t *)&error_code);
+// This must flush any caches
+// and reset the cr3 value to the correct value
+int v3_invalidate_shadow_pts(struct guest_info * core) {
+    struct v3_shdw_impl_state * state = &(core->vm_info->shdw_impl);
+    struct v3_shdw_pg_impl * impl = state->current_impl;
+
+    if (!have_callbacks(core)) { 
+       return impl->invalidate_shdw_pt(core);
+    } else {
+       int rc;
+       struct v3_shdw_pg_event event_pre={SHADOW_INVALIDATE,SHADOW_PREIMPL,0,{0,0,0,0,0,0}};
+       struct v3_shdw_pg_event event_post={SHADOW_INVALIDATE,SHADOW_POSTIMPL,0,{0,0,0,0,0,0}};
+       
+       dispatch_event(core,&event_pre);
+
+       rc = impl->invalidate_shdw_pt(core);
+
+       dispatch_event(core,&event_post);
+       
+       return rc;
+    }
 }
 
 
-static int is_guest_pf(pt_access_status_t guest_access, pt_access_status_t shadow_access) {
-  /* basically the reasoning is that there can be multiple reasons for a page fault:
-     If there is a permissions failure for a page present in the guest _BUT_ 
-     the reason for the fault was that the page is not present in the shadow, 
-     _THEN_ we have to map the shadow page in and reexecute, this will generate 
-     a permissions fault which is _THEN_ valid to send to the guest
-     _UNLESS_ both the guest and shadow have marked the page as not present
+int v3_handle_shadow_pagefault(struct guest_info * core, addr_t fault_addr, pf_error_t error_code) 
+{
+    int rc;
+   
 
-     whew...
-  */
-  if (guest_access != PT_ACCESS_OK) {
-    // Guest Access Error
+    if (have_callbacks(core)) { 
+       struct v3_shdw_pg_event event={SHADOW_PAGEFAULT,SHADOW_PREIMPL,fault_addr,error_code};
+       dispatch_event(core,&event);
+    }
+    
+    if (v3_get_vm_mem_mode(core) == PHYSICAL_MEM) {
+       // If paging is not turned on we need to handle the special cases
+      rc = v3_handle_passthrough_pagefault(core, fault_addr, error_code,NULL,NULL);
+    } else if (v3_get_vm_mem_mode(core) == VIRTUAL_MEM) {
+       struct v3_shdw_impl_state * state = &(core->vm_info->shdw_impl);
+       struct v3_shdw_pg_impl * impl = state->current_impl;
+       
+       rc = impl->handle_pagefault(core, fault_addr, error_code);
+    } else {
+       PrintError(core->vm_info, core, "Invalid Memory mode\n");
+       rc = -1;
+    }
     
-    if ((shadow_access != PT_ACCESS_NOT_PRESENT) &&
-       (guest_access != PT_ACCESS_NOT_PRESENT)) {
-      // aka (guest permission error)
-      return 1;
+    if (have_callbacks(core)) {
+       struct v3_shdw_pg_event event={SHADOW_PAGEFAULT,SHADOW_POSTIMPL,fault_addr,error_code};
+       dispatch_event(core,&event);
+    }
+    
+    return rc;
+}
+
+
+int v3_handle_shadow_invlpg(struct guest_info * core) {
+    uchar_t instr[15];
+    struct x86_instr dec_instr;
+    int ret = 0;
+    addr_t vaddr = 0;
+
+    if (v3_get_vm_mem_mode(core) != VIRTUAL_MEM) {
+       // Paging must be turned on...
+       // should handle with some sort of fault I think
+       PrintError(core->vm_info, core, "ERROR: INVLPG called in non paged mode\n");
+       return -1;
+    }
+
+    if (v3_get_vm_mem_mode(core) == PHYSICAL_MEM) { 
+       ret = v3_read_gpa_memory(core, get_addr_linear(core, core->rip, &(core->segments.cs)), 15, instr);
+    } else { 
+       ret = v3_read_gva_memory(core, get_addr_linear(core, core->rip, &(core->segments.cs)), 15, instr);
+    }
+
+    if (ret == -1) {
+       PrintError(core->vm_info, core, "Could not read instruction into buffer\n");
+       return -1;
     }
 
-    if ((shadow_access == PT_ACCESS_NOT_PRESENT) &&
-       (guest_access == PT_ACCESS_NOT_PRESENT)) {      
-      // Page tables completely blank, handle guest first
-      return 1;
+    if (v3_decode(core, (addr_t)instr, &dec_instr) == -1) {
+       PrintError(core->vm_info, core, "Decoding Error\n");
+       return -1;
+    }
+  
+    if ((dec_instr.op_type != V3_OP_INVLPG) || 
+       (dec_instr.num_operands != 1) ||
+       (dec_instr.dst_operand.type != MEM_OPERAND)) {
+       PrintError(core->vm_info, core, "Decoder Error: Not a valid INVLPG instruction...\n");
+       return -1;
     }
 
-    // Otherwise we'll handle the guest fault later...?
-  }
+    vaddr = dec_instr.dst_operand.operand;
+
+    core->rip += dec_instr.instr_length;
+
+    {
+       struct v3_shdw_impl_state * state = &(core->vm_info->shdw_impl);
+       struct v3_shdw_pg_impl * impl = state->current_impl;
+       int rc;
 
-  return 0;
+       if (have_callbacks(core)) { 
+           struct v3_shdw_pg_event event={SHADOW_INVLPG,SHADOW_PREIMPL,vaddr,{0,0,0,0,0,0}};
+           dispatch_event(core,&event);
+       }
+
+       rc=impl->handle_invlpg(core, vaddr);
+
+       if (have_callbacks(core)) { 
+           struct v3_shdw_pg_event event={SHADOW_INVLPG,SHADOW_POSTIMPL,vaddr,{0,0,0,0,0,0}};
+           dispatch_event(core,&event);
+       }
+
+       return rc;
+    }
 }
 
 
@@ -234,101 +421,100 @@ static int is_guest_pf(pt_access_status_t guest_access, pt_access_status_t shado
 
 
 
+int v3_inject_guest_pf(struct guest_info * core, addr_t fault_addr, pf_error_t error_code) {
+    core->ctrl_regs.cr2 = fault_addr;
 
+#ifdef V3_CONFIG_SHADOW_PAGING_TELEMETRY
+    core->shdw_pg_state.guest_faults++;
+#endif
+
+    return v3_raise_exception_with_error(core, PF_EXCEPTION, *(uint_t *)&error_code);
+}
 
 
+int v3_is_guest_pf(pt_access_status_t guest_access, pt_access_status_t shadow_access) {
+    /* basically the reasoning is that there can be multiple reasons for a page fault:
+       If there is a permissions failure for a page present in the guest _BUT_
+       the reason for the fault was that the page is not present in the shadow,
+       _THEN_ we have to map the shadow page in and reexecute, this will generate
+       a permissions fault which is _THEN_ valid to send to the guest
+       _UNLESS_ both the guest and shadow have marked the page as not present
+
+       whew...
+    */
+    if (guest_access != PT_ACCESS_OK) {
+       // Guest Access Error
+
+       if ((shadow_access != PT_ACCESS_NOT_PRESENT) &&
+           (guest_access != PT_ACCESS_NOT_PRESENT)) {
+           // aka (guest permission error)
+           return 1;
+       }
+
+       /*
+         if ((shadow_access == PT_ACCESS_NOT_PRESENT) &&
+         (guest_access == PT_ACCESS_NOT_PRESENT)) {
+         // Page tables completely blank, handle guest first
+         return 1;
+         }
+       */
+
+       if (guest_access == PT_ACCESS_NOT_PRESENT) {
+           // Page tables completely blank, handle guest first
+           return 1;
+       }
+       
+       // Otherwise we'll handle the guest fault later...?
+    }
 
+    return 0;
+}
 
 
-/* Currently Does not work with Segmentation!!! */
-int v3_handle_shadow_invlpg(struct guest_info * info)
+int v3_register_shadow_paging_event_callback(struct v3_vm_info *vm,
+                                            int (*callback)(struct guest_info *core, 
+                                                            struct v3_shdw_pg_event *event,
+                                                            void      *priv_data),
+                                            void *priv_data)
 {
-  if (info->mem_mode != VIRTUAL_MEM) {
-    // Paging must be turned on...
-    // should handle with some sort of fault I think
-    PrintError("ERROR: INVLPG called in non paged mode\n");
-    return -1;
-  }
-  
-  
-  if (info->cpu_mode != PROTECTED) {
-    PrintError("Unsupported CPU mode (mode=%s)\n", v3_cpu_mode_to_str(info->cpu_mode));
-    return -1;
-  }
-  
-  uchar_t instr[15];
-  int index = 0;
-  
-  int ret = read_guest_va_memory(info, get_addr_linear(info, info->rip, &(info->segments.cs)), 15, instr);
-  if (ret != 15) {
-    PrintError("Could not read instruction 0x%p (ret=%d)\n",  (void *)(addr_t)(info->rip), ret);
-    return -1;
-  }
-  
-  
-  /* Can INVLPG work with Segments?? */
-  while (is_prefix_byte(instr[index])) {
-    index++;
-  }
-    
+    struct event_callback *ec = V3_Malloc(sizeof(struct event_callback));
+
+    if (!ec) { 
+       PrintError(vm, VCORE_NONE, "Unable to allocate for a shadow paging event callback\n");
+       return -1;
+    }
     
-  if( (instr[index + 0] != (uchar_t) 0x0f) ||  
-      (instr[index + 1] != (uchar_t) 0x01) ) {
-    PrintError("invalid Instruction Opcode\n");
-    PrintTraceMemDump(instr, 15);
-    return -1;
-  }
-  
-  addr_t first_operand;
-  addr_t second_operand;
-  addr_t guest_cr3 =  CR3_TO_PDE32_PA(info->shdw_pg_state.guest_cr3);
-  
-  pde32_t * guest_pd = NULL;
-  
-  if (guest_pa_to_host_va(info, guest_cr3, (addr_t*)&guest_pd) == -1) {
-    PrintError("Invalid Guest PDE Address: 0x%p\n",  (void *)guest_cr3);
-    return -1;
-  }
-  
-  index += 2;
+    ec->callback = callback;
+    ec->priv_data = priv_data;
 
-  v3_operand_type_t addr_type = decode_operands32(&(info->vm_regs), instr + index, &index, &first_operand, &second_operand, REG32);
-  
-  if (addr_type != MEM_OPERAND) {
-    PrintError("Invalid Operand type\n");
-    return -1;
-  }
-  
-  pde32_t * shadow_pd = (pde32_t *)CR3_TO_PDE32_VA(info->ctrl_regs.cr3);
-  pde32_t * shadow_pde = (pde32_t *)&shadow_pd[PDE32_INDEX(first_operand)];
-  pde32_t * guest_pde;
-  
-  //PrintDebug("PDE Index=%d\n", PDE32_INDEX(first_operand));
-  //PrintDebug("FirstOperand = %x\n", first_operand);
-  
-  PrintDebug("Invalidating page for %p\n", (void *)first_operand);
-  
-  guest_pde = (pde32_t *)&(guest_pd[PDE32_INDEX(first_operand)]);
-  
-  if (guest_pde->large_page == 1) {
-    shadow_pde->present = 0;
-    PrintDebug("Invalidating Large Page\n");
-  } else
-    if (shadow_pde->present == 1) {
-      pte32_t * shadow_pt = (pte32_t *)(addr_t)BASE_TO_PAGE_ADDR(shadow_pde->pt_base_addr);
-      pte32_t * shadow_pte = (pte32_t *) V3_VAddr( (void*) &shadow_pt[PTE32_INDEX(first_operand)] );
-      
-#ifdef DEBUG_SHADOW_PAGING
-      PrintDebug("Setting not present\n");
-      PrintPTEntry(PAGE_PT32, first_operand, shadow_pte);
-#endif
-      
-      shadow_pte->present = 0;
+    list_add(&(ec->node),&(vm->shdw_impl.event_callback_list));
+
+    return 0;
+
+}
+
+int v3_unregister_shadow_paging_event_callback(struct v3_vm_info *vm,
+                                              int (*callback)(struct guest_info *core, 
+                                                              struct v3_shdw_pg_event *event,
+                                                              void      *priv_data),
+                                              void *priv_data)
+{
+    struct event_callback *cb,*temp;
+
+    list_for_each_entry_safe(cb,
+                            temp,
+                            &(vm->shdw_impl.event_callback_list),
+                            node) {
+       if ((callback == cb->callback) && (priv_data == cb->priv_data)) { 
+           list_del(&(cb->node));
+           V3_Free(cb);
+           return 0;
+       }
     }
-  
-  info->rip += index;
-  
-  return 0;
+    
+    PrintError(vm, VCORE_NONE, "No callback found!\n");
+    
+    return -1;
 }