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 39a024c..10ed641 100644 (file)
+/* 
+ * This file is part of the Palacios Virtual Machine Monitor developed
+ * by the V3VEE Project with funding from the United States National 
+ * Science Foundation and the Department of Energy.  
+ *
+ * The V3VEE Project is a joint project between Northwestern University
+ * and the University of New Mexico.  You can find out more at 
+ * http://www.v3vee.org
+ *
+ * Copyright (c) 2008, Jack Lange <jarusl@cs.northwestern.edu> 
+ * Copyright (c) 2008, The V3VEE Project <http://www.v3vee.org> 
+ * All rights reserved.
+ *
+ * Author: Jack Lange <jarusl@cs.northwestern.edu>
+ *
+ * This is free software.  You are permitted to use,
+ * redistribute, and modify it as specified in the file "V3VEE_LICENSE".
+ */
+
+
 #include <palacios/vmm_shadow_paging.h>
 
 
 #include <palacios/vmm.h>
 #include <palacios/vm_guest_mem.h>
 #include <palacios/vmm_decoder.h>
+#include <palacios/vmm_ctrl_regs.h>
 
+#include <palacios/vmm_hashtable.h>
 
+#include <palacios/vmm_direct_paging.h>
 
-int init_shadow_page_state(struct shadow_page_state * state) {
-  state->guest_mode = PDE32;
-  state->shadow_mode = PDE32;
-  
-  state->guest_cr3 = 0;
-  state->shadow_cr3 = 0;
 
-  return 0;
+
+
+#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
+
+
+static const char default_strategy[] = "VTLB";
+
+
+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 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));
 }
 
-int 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
-    return handle_special_page_fault(info, fault_addr, error_code);
-  } else if (info->mem_mode == VIRTUAL_MEM) {
-
-    switch (info->cpu_mode) {
-    case PROTECTED:
-      return handle_shadow_pagefault32(info, fault_addr, error_code);
-      break;
-    case PROTECTED_PAE:
-    case LONG:
-      // currently not handled
-      return -1;
-      break;
-    default:
-      return -1;
+static int shdw_pg_eq_fn(addr_t key1, addr_t key2) {
+    char * name1 = (char *)key1;
+    char * name2 = (char *)key2;
+
+    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);
     }
-  } else {
-    PrintDebug("Invalid Memory mode\n");
-    return -1;
-  }
 }
 
 
-int handle_shadow_pagefault32(struct guest_info * info, addr_t fault_addr, pf_error_t error_code) {
-  pde32_t * guest_pde = NULL;
-  pde32_t * shadow_pde = (pde32_t *)CR3_TO_PDE32(info->shdw_pg_state.shadow_cr3);
-  addr_t guest_cr3 = CR3_TO_PDE32(info->shdw_pg_state.guest_cr3);
-  pt_access_status_t guest_pde_access;
-  pt_access_status_t shadow_pde_access;
-  pde32_t * guest_pde_entry = NULL;
-  pde32_t * shadow_pde_entry = (pde32_t *)&(shadow_pde[PDE32_INDEX(fault_addr)]);
+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;
 
-  if (guest_pa_to_host_va(info, guest_cr3, (addr_t*)&guest_pde) == -1) {
-    PrintDebug("Invalid Guest PDE Address: 0x%x\n", guest_cr3);
-    return -1;
-  }
+    master_shdw_pg_table = v3_create_htable(0, shdw_pg_hash_fn, shdw_pg_eq_fn);
 
 
-  guest_pde_entry = (pde32_t *)&(guest_pde[PDE32_INDEX(fault_addr)]);
+    while (tmp_impl != __stop__v3_shdw_pg_impls) {
+       V3_Print(VM_NONE, VCORE_NONE, "Registering Shadow Paging Impl (%s)\n", (*tmp_impl)->name);
 
-  // Check the guest page permissions
-  guest_pde_access = can_access_pde32(guest_pde, fault_addr, error_code);
+       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 (guest_pde_access != PT_ACCESS_OK) {
-    // inject page fault to the guest (Guest PDE fault)
+       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;
+       }
 
-    info->ctrl_regs.cr2 = fault_addr;
-    raise_exception_with_error(info, PF_EXCEPTION, *(uint_t *)&error_code);
+       tmp_impl = &(__start__v3_shdw_pg_impls[++i]);
+    }
 
-    PrintDebug("Injecting PDE pf to guest\n");
     return 0;
-  }
+}
 
+int V3_deinit_shdw_paging() {
+    v3_free_htable(master_shdw_pg_table, 0, 0);
+    return 0;
+}
 
-  // Check that the Guest PDE entry points to valid memory
-  // else Machine Check the guest
 
-  shadow_pde_access = can_access_pde32(shadow_pde, fault_addr, error_code);
 
+/*** 
+ ***  There be dragons
+ ***/
 
-  if (shadow_pde_access == PT_ENTRY_NOT_PRESENT) {
-    pte32_t * shadow_pte = NULL;
 
-    V3_AllocPages(shadow_pte, 1);
-    memset(shadow_pte, 0, PAGE_SIZE);
+#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]);
 
-    shadow_pde_entry->pt_base_addr = PD32_BASE_ADDR(shadow_pte);
-    
+       V3_Print(vm, core, "%s Guest Page faults: %d\n", hdr, core->shdw_pg_state.guest_faults);
+    }
+}
+#endif
 
-    shadow_pde_entry->present = 1;
-    shadow_pde_entry->user_page = guest_pde_entry->user_page;
-    
-    // VMM Specific options
-    shadow_pde_entry->write_through = 0;
-    shadow_pde_entry->cache_disable = 0;
-    shadow_pde_entry->global_page = 0;
-    //
 
-    guest_pde_entry->accessed = 1;
 
-    if (guest_pde_entry->large_page == 0) {
-      shadow_pde_entry->writable = guest_pde_entry->writable;
-    } else {
-      /*
-       * Check the Intel manual because we are ignoring Large Page issues here
-       * Also be wary of hooked pages
-       */
+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;
+  
 
-      PrintDebug("Large PAge!!!\n");
-      return -1;
+    state->guest_cr3 = 0;
+    state->guest_cr0 = 0;
+    state->guest_efer.value = 0x0LL;
 
+    if (impl->local_init(core) == -1) {
+       PrintError(core->vm_info, core, "Error in Shadow paging local initialization (%s)\n", impl->name);
+       return -1;
     }
 
-  } else if (shadow_pde_access == PT_WRITE_ERROR) {
 
-    //
-    // Page Directory Entry marked read-only
-    //
+#ifdef V3_CONFIG_SHADOW_PAGING_TELEMETRY
+    v3_add_telemetry_cb(core->vm_info, telemetry_cb, NULL);
+#endif
+  
 
-    PrintDebug("Shadow Paging Write Error\n");
-    return -1;
-  } else if (shadow_pde_access == PT_USER_ERROR) {
+    return 0;
+}
 
-    //
-    // Page Directory Entry marked non-user
-    //
-    
-    PrintDebug("Shadow Paging User access error\n");
-    return -1;
-  } else if (shadow_pde_access == PT_ACCESS_OK) {
-    pte32_t * shadow_pte = (pte32_t *)PDE32_T_ADDR((*shadow_pde_entry));
-    pte32_t * guest_pte = NULL;
 
-    // Page Table Entry fault
-    
-    if (guest_pa_to_host_va(info, PDE32_T_ADDR((*guest_pde_entry)), (addr_t*)&guest_pte) == -1) {
-      PrintDebug("Invalid Guest PTE Address: 0x%x\n", PDE32_T_ADDR((*guest_pde_entry)));
-      // Machine check the guest
+int v3_deinit_shdw_pg_state(struct guest_info * core) {
+    struct v3_shdw_pg_impl * impl = NULL;
 
-      raise_exception(info, MC_EXCEPTION);
-      
-      return 0;
+    if (!core || !core->vm_info) {
+        return -1;
     }
 
+    impl = core->vm_info->shdw_impl.current_impl;
 
-    if (handle_shadow_pte32_fault(info, fault_addr, error_code, shadow_pte, guest_pte)  == -1) {
-      PrintDebug("Error handling Page fault caused by PTE\n");
-      return -1;
+    if (impl && impl->local_deinit(core) == -1) {
+       PrintError(core->vm_info, core, "Error deinitializing shadow paging state\n");
+       return -1;
     }
 
- } else {
-    // Unknown error raise page fault in guest
-    info->ctrl_regs.cr2 = fault_addr;
-    raise_exception_with_error(info, PF_EXCEPTION, *(uint_t *)&error_code);
 
-    // For debugging we will return an error here for the time being, 
-    // this probably shouldn't ever happen
-    PrintDebug("Unknown Error occurred\n");
-    PrintDebug("Manual Says to inject page fault into guest\n");
-    return -1;
-  }
-
-  //PrintDebugPageTables(shadow_pde);
-  PrintDebug("Returning end of PDE function\n");
-  return 0;
+    return 0;
 }
 
 
 
-/* 
- * We assume the the guest pte pointer has already been translated to a host virtual address
- */
-int handle_shadow_pte32_fault(struct guest_info * info, 
-                             addr_t fault_addr, 
-                             pf_error_t error_code,
-                             pte32_t * shadow_pte, 
-                             pte32_t * guest_pte) {
+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";
+       }
+    }
 
-  pt_access_status_t guest_pte_access;
-  pt_access_status_t shadow_pte_access;
-  pte32_t * guest_pte_entry = (pte32_t *)&(guest_pte[PTE32_INDEX(fault_addr)]);;
-  pte32_t * shadow_pte_entry = (pte32_t *)&(shadow_pte[PTE32_INDEX(fault_addr)]);
+    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);
 
-  // Check the guest page permissions
-  guest_pte_access = can_access_pte32(guest_pte, fault_addr, error_code);
+    if (impl == NULL) {
+       PrintError(vm, VCORE_NONE, "Could not find shadow paging impl (%s)\n", pg_strat);
+       return -1;
+    }
 
-  
-  if (guest_pte_access != PT_ACCESS_OK) {
-    // Inject page fault into the guest        
-    
-    info->ctrl_regs.cr2 = fault_addr;
-    raise_exception_with_error(info, PF_EXCEPTION, *(uint_t *)&error_code);
-    
-    PrintDebug("Access error injecting pf to guest\n");
-    return 0;
-  }
-  
-  
-  shadow_pte_access = can_access_pte32(shadow_pte, fault_addr, error_code);
+    INIT_LIST_HEAD(&(impl_state->event_callback_list));
+   
+    impl_state->current_impl = impl;
 
-  if (shadow_pte_access == PT_ACCESS_OK) {
-    // Inconsistent state...
-    // Guest Re-Entry will flush page tables and everything should now work
-    PrintDebug("Inconsistent state... Guest re-entry should flush tlb\n");
-    return 0;
-  } else if (shadow_pte_access == PT_ENTRY_NOT_PRESENT) {
-    addr_t shadow_pa;
-    addr_t guest_pa = PTE32_T_ADDR((*guest_pte_entry));
-
-    // Page Table Entry Not Present
-
-    host_region_type_t host_page_type = get_shadow_addr_type(info, guest_pa);
-
-    if (host_page_type == HOST_REGION_INVALID) {
-      // Inject a machine check in the guest
-
-      raise_exception(info, MC_EXCEPTION);
-
-      PrintDebug("Invalid Guest Address in page table (0x%x)\n", guest_pa);
-      return 0;
-
-    } else if (host_page_type == HOST_REGION_PHYSICAL_MEMORY) {
-      
-      shadow_pa = get_shadow_addr(info, guest_pa);
-      
-      shadow_pte_entry->page_base_addr = PT32_BASE_ADDR(shadow_pa);
-      
-      shadow_pte_entry->present = guest_pte_entry->present;
-      shadow_pte_entry->user_page = guest_pte_entry->user_page;
-      
-      //set according to VMM policy
-      shadow_pte_entry->write_through = 0;
-      shadow_pte_entry->cache_disable = 0;
-      shadow_pte_entry->global_page = 0;
-      //
-      
-      guest_pte_entry->accessed = 1;
-      
-      if (guest_pte_entry->dirty == 1) {
-       shadow_pte_entry->writable = guest_pte_entry->writable;
-      } else if ((guest_pte_entry->dirty == 0) && (error_code.write == 1)) {
-       shadow_pte_entry->writable = guest_pte_entry->writable;
-       guest_pte_entry->dirty = 1;
-      } else if ((guest_pte_entry->dirty = 0) && (error_code.write == 0)) {
-       shadow_pte_entry->writable = 0;
-      }
-    } else {
-      // Page fault handled by hook functions
-      if (handle_special_page_fault(info, fault_addr, error_code) == -1) {
-       PrintDebug("Special Page fault handler returned error for address: %x\n", fault_addr);
+    if (impl->init(vm, pg_cfg) == -1) {
+       PrintError(vm, VCORE_NONE, "Could not initialize Shadow paging implemenation (%s)\n", impl->name);
        return -1;
-      }
     }
 
-  } else if ((shadow_pte_access == PT_WRITE_ERROR) &&
-            (guest_pte_entry->dirty == 0)) {
-    guest_pte_entry->dirty = 1;
-    shadow_pte_entry->writable = guest_pte_entry->writable;
 
-    PrintDebug("Shadow PTE Write Error\n");
 
     return 0;
-  } else {
-    // Inject page fault into the guest        
-       
-    info->ctrl_regs.cr2 = fault_addr;
-    raise_exception_with_error(info, PF_EXCEPTION, *(uint_t *)&error_code);
+}
 
-    PrintDebug("PTE Page fault fell through... Not sure if this should ever happen\n");
-    PrintDebug("Manual Says to inject page fault into guest\n");
-    return -1;
-  }
+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;
 
-  PrintDebug("Returning end of function\n");
-  return 0;
-}
+    if (impl == NULL) {
+       // Shadow paging not implemented
+       return 0;
+    }
 
+    if (impl->deinit(vm) == -1) {
+       PrintError(vm, VCORE_NONE,"Error deinitializing shadow paging implementation\n");
+       return -1;
+    }
+
+    list_for_each_entry_safe(cb,
+                            temp,
+                            &(vm->shdw_impl.event_callback_list),
+                            node) {
+       list_del(&(cb->node));
+       V3_Free(cb);
+    }
 
+    return 0;
+}
 
-addr_t create_new_shadow_pt32(struct guest_info * info) {
-  void * host_pde = 0;
 
-  V3_AllocPages(host_pde, 1);
-  memset(host_pde, 0, PAGE_SIZE);
+// 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);
 
-  return (addr_t)host_pde;
+       rc =impl->activate_shdw_pt(core);
+
+       dispatch_event(core,&event_post);
+       
+       return rc;
+    }
 }
 
 
 
-/* Currently Does not work with Segmentation!!! */
-int handle_shadow_invlpg(struct guest_info * info) {
-  if (info->mem_mode != VIRTUAL_MEM) {
-    // Paging must be turned on...
-    // should handle with some sort of fault I think
-    PrintDebug("ERROR: INVLPG called in non paged mode\n");
-    return -1;
-  }
+// 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);
 
-  if (info->cpu_mode == PROTECTED) {
-    char instr[15];
-    int ret;
-    int index = 0;
+       rc = impl->invalidate_shdw_pt(core);
 
-    ret = read_guest_va_memory(info, get_addr_linear(info, info->rip, &(info->segments.cs)), 15, instr);
-    if (ret != 15) {
-      PrintDebug("Could not read instruction 0x%x (ret=%d)\n", info->rip, ret);
-      return -1;
+       dispatch_event(core,&event_post);
+       
+       return rc;
     }
+}
+
 
+int v3_handle_shadow_pagefault(struct guest_info * core, addr_t fault_addr, pf_error_t error_code) 
+{
+    int rc;
    
-    /* Can INVLPG work with Segments?? */
-    while (is_prefix_byte(instr[index])) {
-      index++;
+
+    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 ((instr[index] == (uchar_t)0x0f) &&
-       (instr[index + 1] == (uchar_t)0x01)) {
+    if (have_callbacks(core)) {
+       struct v3_shdw_pg_event event={SHADOW_PAGEFAULT,SHADOW_POSTIMPL,fault_addr,error_code};
+       dispatch_event(core,&event);
+    }
+    
+    return rc;
+}
 
-      addr_t first_operand;
-      addr_t second_operand;
-      operand_type_t addr_type;
 
-      index += 2;
+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;
 
-      addr_type = decode_operands32(&(info->vm_regs), instr + index, &index, &first_operand, &second_operand, REG32);
+    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 (addr_type == MEM_OPERAND) {
-       pde32_t * shadow_pd = (pde32_t *)CR3_TO_PDE32(info->shdw_pg_state.shadow_cr3);
-       pde32_t * shadow_pde_entry = (pde32_t *)&shadow_pd[PDE32_INDEX(first_operand)];
+    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);
+    }
 
-       //PrintDebug("PDE Index=%d\n", PDE32_INDEX(first_operand));
-       //PrintDebug("FirstOperand = %x\n", first_operand);
+    if (ret == -1) {
+       PrintError(core->vm_info, core, "Could not read instruction into buffer\n");
+       return -1;
+    }
 
-       if (shadow_pde_entry->large_page == 1) {
-         shadow_pde_entry->present = 0;
-       } else {
-         if (shadow_pde_entry->present == 1) {
-           pte32_t * shadow_pt = (pte32_t *)PDE32_T_ADDR((*shadow_pde_entry));
-           pte32_t * shadow_pte_entry = (pte32_t *)&shadow_pt[PTE32_INDEX(first_operand)];
+    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;
+    }
 
-           shadow_pte_entry->present = 0;
-         }
+    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;
+
+       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);
        }
 
-       info->rip += index;
+       rc=impl->handle_invlpg(core, vaddr);
 
-      } else {
-       PrintDebug("Invalid Operand type\n");
-       return -1;
-      }
-    } else {
-      PrintDebug("invalid Instruction Opcode\n");
-      PrintTraceMemDump(instr, 15);
-      return -1;
-    }
-  }
+       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 0;
+       return rc;
+    }
 }
 
 
 
-/* Deprecated */
-/*
-addr_t setup_shadow_pt32(struct guest_info * info, addr_t virt_cr3) {
-  addr_t cr3_guest_addr = CR3_TO_PDE32(virt_cr3);
-  pde32_t * guest_pde;
-  pde32_t * host_pde = NULL;
-  int i;
-  
-  // Setup up guest_pde to point to the PageDir in host addr
-  if (guest_pa_to_host_va(info, cr3_guest_addr, (addr_t*)&guest_pde) == -1) {
-    return 0;
-  }
-  
-  V3_AllocPages(host_pde, 1);
-  memset(host_pde, 0, PAGE_SIZE);
 
-  for (i = 0; i < MAX_PDE32_ENTRIES; i++) {
-    if (guest_pde[i].present == 1) {
-      addr_t pt_host_addr;
-      addr_t host_pte;
 
-      if (guest_pa_to_host_va(info, PDE32_T_ADDR(guest_pde[i]), &pt_host_addr) == -1) {
-       return 0;
-      }
 
-      if ((host_pte = setup_shadow_pte32(info, pt_host_addr)) == 0) {
-       return 0;
-      }
+int v3_inject_guest_pf(struct guest_info * core, addr_t fault_addr, pf_error_t error_code) {
+    core->ctrl_regs.cr2 = fault_addr;
 
-      host_pde[i].present = 1;
-      host_pde[i].pt_base_addr = PD32_BASE_ADDR(host_pte);
+#ifdef V3_CONFIG_SHADOW_PAGING_TELEMETRY
+    core->shdw_pg_state.guest_faults++;
+#endif
 
-      //
-      // Set Page DIR flags
-      //
-    }
-  }
+    return v3_raise_exception_with_error(core, PF_EXCEPTION, *(uint_t *)&error_code);
+}
 
-  PrintDebugPageTables(host_pde);
 
-  return (addr_t)host_pde;
-}
+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;
+       }
 
-addr_t setup_shadow_pte32(struct guest_info * info, addr_t pt_host_addr) {
-  pte32_t * guest_pte = (pte32_t *)pt_host_addr;
-  pte32_t * host_pte = NULL;
-  int i;
+       /*
+         if ((shadow_access == PT_ACCESS_NOT_PRESENT) &&
+         (guest_access == PT_ACCESS_NOT_PRESENT)) {
+         // Page tables completely blank, handle guest first
+         return 1;
+         }
+       */
 
-  V3_AllocPages(host_pte, 1);
-  memset(host_pte, 0, PAGE_SIZE);
+       if (guest_access == PT_ACCESS_NOT_PRESENT) {
+           // Page tables completely blank, handle guest first
+           return 1;
+       }
+       
+       // Otherwise we'll handle the guest fault later...?
+    }
 
-  for (i = 0; i < MAX_PTE32_ENTRIES; i++) {
-    if (guest_pte[i].present == 1) {
-      addr_t guest_pa = PTE32_T_ADDR(guest_pte[i]);
-      shadow_mem_type_t page_type;
-      addr_t host_pa = 0;
+    return 0;
+}
 
-      page_type = get_shadow_addr_type(info, guest_pa);
 
-      if (page_type == HOST_REGION_PHYSICAL_MEMORY) {
-       host_pa = get_shadow_addr(info, guest_pa);
-      } else {
-       
-       //
-       // Setup various memory types
-       //
-      }
+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)
+{
+    struct event_callback *ec = V3_Malloc(sizeof(struct event_callback));
 
-      host_pte[i].page_base_addr = PT32_BASE_ADDR(host_pa);
-      host_pte[i].present = 1;
+    if (!ec) { 
+       PrintError(vm, VCORE_NONE, "Unable to allocate for a shadow paging event callback\n");
+       return -1;
     }
-  }
+    
+    ec->callback = callback;
+    ec->priv_data = priv_data;
+
+    list_add(&(ec->node),&(vm->shdw_impl.event_callback_list));
+
+    return 0;
 
-  return (addr_t)host_pte;
 }
 
-*/
+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;
+       }
+    }
+    
+    PrintError(vm, VCORE_NONE, "No callback found!\n");
+    
+    return -1;
+}
+
+