/* 
 * 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".
 */


static inline int activate_shadow_pt_64(struct guest_info * info) {
    struct cr3_64 * shadow_cr3 = (struct cr3_64 *)&(info->ctrl_regs.cr3);
    struct cr3_64 * guest_cr3 = (struct cr3_64 *)&(info->shdw_pg_state.guest_cr3);
    struct shadow_page_data * shadow_pt = create_new_shadow_pt(info);
    addr_t shadow_pt_addr = shadow_pt->page_pa;

    // Because this is a new CR3 load the allocated page is the new CR3 value
    shadow_pt->cr3 = shadow_pt->page_pa;

    PrintDebug("Top level Shadow page pa=%p\n", (void *)shadow_pt_addr);

    shadow_cr3->pml4t_base_addr = PAGE_BASE_ADDR_4KB(shadow_pt_addr);
    PrintDebug("Creating new 64 bit shadow page table %p\n", (void *)BASE_TO_PAGE_ADDR(shadow_cr3->pml4t_base_addr));

  
    shadow_cr3->pwt = guest_cr3->pwt;
    shadow_cr3->pcd = guest_cr3->pcd;

    return 0;
}






/* 
 * *
 * * 
 * * 64 bit Page table fault handlers
 * *
 * *
 */

static int handle_2MB_shadow_pagefault_64(struct guest_info * info, addr_t fault_addr, pf_error_t error_code,
					  pte64_t * shadow_pt, pde64_2MB_t * large_guest_pde);

static int handle_pte_shadow_pagefault_64(struct guest_info * info, addr_t fault_addr, pf_error_t error_code,
					  pte64_t * shadow_pt, pte64_t * guest_pt);

static int handle_pde_shadow_pagefault_64(struct guest_info * info, addr_t fault_addr, pf_error_t error_code,
					  pde64_t * shadow_pd, pde64_t * guest_pd);

static int handle_pdpe_shadow_pagefault_64(struct guest_info * info, addr_t fault_addr, pf_error_t error_code,
					   pdpe64_t * shadow_pdp, pdpe64_t * guest_pdp);


static inline int handle_shadow_pagefault_64(struct guest_info * info, addr_t fault_addr, pf_error_t error_code) {
    pml4e64_t * guest_pml = NULL;
    pml4e64_t * shadow_pml = CR3_TO_PML4E64_VA(info->ctrl_regs.cr3);
    addr_t guest_cr3 = CR3_TO_PML4E64_PA(info->shdw_pg_state.guest_cr3);
    pt_access_status_t guest_pml4e_access;
    pt_access_status_t shadow_pml4e_access;
    pml4e64_t * guest_pml4e = NULL;
    pml4e64_t * shadow_pml4e = (pml4e64_t *)&(shadow_pml[PML4E64_INDEX(fault_addr)]);

    PrintDebug("64 bit Shadow page fault handler: %p\n", (void *)fault_addr);
    PrintDebug("Handling PML fault\n");

    if (guest_pa_to_host_va(info, guest_cr3, (addr_t*)&guest_pml) == -1) {
	PrintError("Invalid Guest PML4E Address: 0x%p\n",  (void *)guest_cr3);
	return -1;
    } 

    guest_pml4e = (pml4e64_t *)&(guest_pml[PML4E64_INDEX(fault_addr)]);

    PrintDebug("Checking Guest %p\n", (void *)guest_pml);
    // Check the guest page permissions
    guest_pml4e_access = v3_can_access_pml4e64(guest_pml, fault_addr, error_code);

    PrintDebug("Checking shadow %p\n", (void *)shadow_pml);
    // Check the shadow page permissions
    shadow_pml4e_access = v3_can_access_pml4e64(shadow_pml, fault_addr, error_code);
  
    /* Was the page fault caused by the Guest's page tables? */
    if (is_guest_pf(guest_pml4e_access, shadow_pml4e_access) == 1) {
	PrintDebug("Injecting PML4E pf to guest: (guest access error=%d) (pf error code=%d)\n", 
		   *(uint_t *)&guest_pml4e_access, *(uint_t *)&error_code);
	if (inject_guest_pf(info, fault_addr, error_code) == -1) {
	    PrintError("Could not inject guest page fault\n");
	    return -1;
	}
	return 0;
    }

    if (shadow_pml4e_access == PT_ACCESS_USER_ERROR) {
	//
	// PML4 Entry marked non-user
	//      
	PrintDebug("Shadow Paging User access error (shadow_pml4e_access=0x%x, guest_pml4e_access=0x%x)\n", 
		   shadow_pml4e_access, guest_pml4e_access);
	if (inject_guest_pf(info, fault_addr, error_code) == -1) {
	    PrintError("Could not inject guest page fault\n");
	    return -1;
	}
	return 0;
    } else if ((shadow_pml4e_access != PT_ACCESS_NOT_PRESENT) &&
	       (shadow_pml4e_access != PT_ACCESS_OK)) {
	// inject page fault in guest
	if (inject_guest_pf(info, fault_addr, error_code) == -1) {
	    PrintError("Could not inject guest page fault\n");
	    return -1;
	}
	PrintDebug("Unknown Error occurred (shadow_pde_access=%d)\n", shadow_pml4e_access);
	PrintDebug("Manual Says to inject page fault into guest\n");
	return 0;
    }


    pdpe64_t * shadow_pdp = NULL;
    pdpe64_t * guest_pdp = NULL;

    // Get the next shadow page level, allocate if not present

    if (shadow_pml4e_access == PT_ACCESS_NOT_PRESENT) {
	struct shadow_page_data * shdw_page =  create_new_shadow_pt(info);
	shadow_pdp = (pdpe64_t *)V3_VAddr((void *)shdw_page->page_pa);


	shadow_pml4e->present = 1;
	shadow_pml4e->user_page = guest_pml4e->user_page;
	shadow_pml4e->writable = guest_pml4e->writable;
	shadow_pml4e->cache_disable = guest_pml4e->cache_disable;
	shadow_pml4e->write_through = guest_pml4e->write_through;
    
	guest_pml4e->accessed = 1;
    
	shadow_pml4e->pdp_base_addr = PAGE_BASE_ADDR(shdw_page->page_pa);
    } else {
	shadow_pdp = (pdpe64_t *)V3_VAddr((void *)(addr_t)BASE_TO_PAGE_ADDR(shadow_pml4e->pdp_base_addr));
    }

    // Continue processing at the next level

    if (guest_pa_to_host_va(info, BASE_TO_PAGE_ADDR(guest_pml4e->pdp_base_addr), (addr_t *)&guest_pdp) == -1) {
	// Machine check the guest
	PrintError("Invalid Guest PDP Address: 0x%p\n", (void *)BASE_TO_PAGE_ADDR(guest_pml4e->pdp_base_addr));
	v3_raise_exception(info, MC_EXCEPTION);
	return 0;
    }
  
    if (handle_pdpe_shadow_pagefault_64(info, fault_addr, error_code, shadow_pdp, guest_pdp) == -1) {
	PrintError("Error handling Page fault caused by PDPE\n");
	return -1;
    }

    return 0;
}



// For now we are not going to handle 1 Gigabyte pages
static int handle_pdpe_shadow_pagefault_64(struct guest_info * info, addr_t fault_addr, pf_error_t error_code,
					   pdpe64_t * shadow_pdp, pdpe64_t * guest_pdp) {
    pt_access_status_t guest_pdpe_access;
    pt_access_status_t shadow_pdpe_access;
    pdpe64_t * guest_pdpe = (pdpe64_t *)&(guest_pdp[PDPE64_INDEX(fault_addr)]);
    pdpe64_t * shadow_pdpe = (pdpe64_t *)&(shadow_pdp[PDPE64_INDEX(fault_addr)]);
 
    PrintDebug("Handling PDP fault\n");

    if (fault_addr==0) { 
	PrintDebug("Guest Page Tree for guest virtual address zero fault\n");
	PrintGuestPageTree(info,fault_addr,(addr_t)(info->shdw_pg_state.guest_cr3));
	PrintDebug("Host Page Tree for guest virtual address zero fault\n");
	PrintHostPageTree(info,fault_addr,(addr_t)(info->ctrl_regs.cr3));
    }

    // Check the guest page permissions
    guest_pdpe_access = v3_can_access_pdpe64(guest_pdp, fault_addr, error_code);

    // Check the shadow page permissions
    shadow_pdpe_access = v3_can_access_pdpe64(shadow_pdp, fault_addr, error_code);
  
    /* Was the page fault caused by the Guest's page tables? */
    if (is_guest_pf(guest_pdpe_access, shadow_pdpe_access) == 1) {
	PrintDebug("Injecting PDPE pf to guest: (guest access error=%d) (pf error code=%d)\n", 
		   *(uint_t *)&guest_pdpe_access, *(uint_t *)&error_code);
	if (inject_guest_pf(info, fault_addr, error_code) == -1) {
	    PrintError("Could not inject guest page fault\n");
	    return -1;
	}
	return 0;
    }

    if (shadow_pdpe_access == PT_ACCESS_USER_ERROR) {
	//
	// PML4 Entry marked non-user
	//      
	PrintDebug("Shadow Paging User access error (shadow_pdpe_access=0x%x, guest_pdpe_access=0x%x)\n", 
		   shadow_pdpe_access, guest_pdpe_access);
	if (inject_guest_pf(info, fault_addr, error_code) == -1) {
	    PrintError("Could not inject guest page fault\n");
	    return -1;
	}
	return 0;
    } else if ((shadow_pdpe_access != PT_ACCESS_NOT_PRESENT) &&
	       (shadow_pdpe_access != PT_ACCESS_OK)) {
	// inject page fault in guest
	if (inject_guest_pf(info, fault_addr, error_code) == -1) {
	    PrintError("Could not inject guest page fault\n");
	    return -1;
	}
	PrintDebug("Unknown Error occurred (shadow_pde_access=%d)\n", shadow_pdpe_access);
	PrintDebug("Manual Says to inject page fault into guest\n");
	return 0;
    }


    pde64_t * shadow_pd = NULL;
    pde64_t * guest_pd = NULL;

    // Get the next shadow page level, allocate if not present

    if (shadow_pdpe_access == PT_ACCESS_NOT_PRESENT) {
	struct shadow_page_data * shdw_page = create_new_shadow_pt(info);
	shadow_pd = (pde64_t *)V3_VAddr((void *)shdw_page->page_pa);


	shadow_pdpe->present = 1;
	shadow_pdpe->user_page = guest_pdpe->user_page;
	shadow_pdpe->writable = guest_pdpe->writable;
	shadow_pdpe->write_through = guest_pdpe->write_through;
	shadow_pdpe->cache_disable = guest_pdpe->cache_disable;

    
	guest_pdpe->accessed = 1;
    
	shadow_pdpe->pd_base_addr = PAGE_BASE_ADDR(shdw_page->page_pa);
    } else {
	shadow_pd = (pde64_t *)V3_VAddr((void *)(addr_t)BASE_TO_PAGE_ADDR(shadow_pdpe->pd_base_addr));
    }

    // Continue processing at the next level

    if (guest_pa_to_host_va(info, BASE_TO_PAGE_ADDR(guest_pdpe->pd_base_addr), (addr_t *)&guest_pd) == -1) {
	// Machine check the guest
	PrintError("Invalid Guest PTE Address: 0x%p\n", (void *)BASE_TO_PAGE_ADDR(guest_pdpe->pd_base_addr));
	v3_raise_exception(info, MC_EXCEPTION);
	return 0;
    }
  
    if (handle_pde_shadow_pagefault_64(info, fault_addr, error_code, shadow_pd, guest_pd) == -1) {
	PrintError("Error handling Page fault caused by PDE\n");
	return -1;
    }

    return 0;
}


static int handle_pde_shadow_pagefault_64(struct guest_info * info, addr_t fault_addr, pf_error_t error_code,
					  pde64_t * shadow_pd, pde64_t * guest_pd) {
    pt_access_status_t guest_pde_access;
    pt_access_status_t shadow_pde_access;
    pde64_t * guest_pde = (pde64_t *)&(guest_pd[PDE64_INDEX(fault_addr)]);
    pde64_t * shadow_pde = (pde64_t *)&(shadow_pd[PDE64_INDEX(fault_addr)]);

    PrintDebug("Handling PDE fault\n");
 
    // Check the guest page permissions
    guest_pde_access = v3_can_access_pde64(guest_pd, fault_addr, error_code);

    // Check the shadow page permissions
    shadow_pde_access = v3_can_access_pde64(shadow_pd, fault_addr, error_code);
  
    /* Was the page fault caused by the Guest's page tables? */
    if (is_guest_pf(guest_pde_access, shadow_pde_access) == 1) {
	PrintDebug("Injecting PDE pf to guest: (guest access error=%d) (pf error code=%d)\n", 
		   *(uint_t *)&guest_pde_access, *(uint_t *)&error_code);
	if (inject_guest_pf(info, fault_addr, error_code) == -1) {
	    PrintError("Could not inject guest page fault\n");
	    return -1;
	}
	return 0;
    }

    if (shadow_pde_access == PT_ACCESS_USER_ERROR) {
	//
	// PDE Entry marked non-user
	//      
	PrintDebug("Shadow Paging User access error (shadow_pdpe_access=0x%x, guest_pdpe_access=0x%x)\n", 
		   shadow_pde_access, guest_pde_access);
	if (inject_guest_pf(info, fault_addr, error_code) == -1) {
	    PrintError("Could not inject guest page fault\n");
	    return -1;
	}
	return 0;

    } else if ((shadow_pde_access == PT_ACCESS_WRITE_ERROR) && 
	       (guest_pde->large_page == 1)) {

	((pde64_2MB_t *)guest_pde)->dirty = 1;
	shadow_pde->writable = guest_pde->writable;

	//PrintDebug("Returning due to large page Write Error\n");
	//PrintHostPageTree(info, fault_addr, info->ctrl_regs.cr3);

	return 0;
    } else if ((shadow_pde_access != PT_ACCESS_NOT_PRESENT) &&
	       (shadow_pde_access != PT_ACCESS_OK)) {
	// inject page fault in guest
	if (inject_guest_pf(info, fault_addr, error_code) == -1) {
	    PrintError("Could not inject guest page fault\n");
	    return -1;
	}
	PrintDebug("Unknown Error occurred (shadow_pde_access=%d)\n", shadow_pde_access);
	PrintDebug("Manual Says to inject page fault into guest\n");
	return 0;
    }


    pte64_t * shadow_pt = NULL;
    pte64_t * guest_pt = NULL;

    // Get the next shadow page level, allocate if not present

    if (shadow_pde_access == PT_ACCESS_NOT_PRESENT) {
	struct shadow_page_data * shdw_page = create_new_shadow_pt(info);
	shadow_pt = (pte64_t *)V3_VAddr((void *)shdw_page->page_pa);

	PrintDebug("Creating new shadow PT: %p\n", shadow_pt);

	shadow_pde->present = 1;
	shadow_pde->user_page = guest_pde->user_page;


	if (guest_pde->large_page == 0) {
	    shadow_pde->writable = guest_pde->writable;
	} else {
	    // This large page flag is temporary until we can get a working cache....
	    ((pde64_2MB_t *)guest_pde)->vmm_info = V3_LARGE_PG;

	    if (error_code.write) {
		shadow_pde->writable = guest_pde->writable;
		((pde64_2MB_t *)guest_pde)->dirty = 1;	
	    } else {
		shadow_pde->writable = 0;
		((pde64_2MB_t *)guest_pde)->dirty = 0;
	    }
	}
    
	// VMM Specific options
	shadow_pde->write_through = guest_pde->write_through;
	shadow_pde->cache_disable = guest_pde->cache_disable;
	shadow_pde->global_page = guest_pde->global_page;
	//
    
	guest_pde->accessed = 1;
    
	shadow_pde->pt_base_addr = PAGE_BASE_ADDR(shdw_page->page_pa);
    } else {
	shadow_pt = (pte64_t *)V3_VAddr((void *)BASE_TO_PAGE_ADDR(shadow_pde->pt_base_addr));
    }

    // Continue processing at the next level
    if (guest_pde->large_page == 0) {
	if (guest_pa_to_host_va(info, BASE_TO_PAGE_ADDR(guest_pde->pt_base_addr), (addr_t *)&guest_pt) == -1) {
	    // Machine check the guest
	    PrintError("Invalid Guest PTE Address: 0x%p\n", (void *)BASE_TO_PAGE_ADDR(guest_pde->pt_base_addr));
	    v3_raise_exception(info, MC_EXCEPTION);
	    return 0;
	}
    
	if (handle_pte_shadow_pagefault_64(info, fault_addr, error_code, shadow_pt, guest_pt) == -1) {
	    PrintError("Error handling Page fault caused by PDE\n");
	    return -1;
	}
    } else {
	if (handle_2MB_shadow_pagefault_64(info, fault_addr, error_code, shadow_pt, (pde64_2MB_t *)guest_pde) == -1) {
	    PrintError("Error handling large pagefault\n");
	    return -1;
	} 
    }

    return 0;
}


static int handle_pte_shadow_pagefault_64(struct guest_info * info, addr_t fault_addr, pf_error_t error_code,
					  pte64_t * shadow_pt, pte64_t * guest_pt) {
    pt_access_status_t guest_pte_access;
    pt_access_status_t shadow_pte_access;
    pte64_t * guest_pte = (pte64_t *)&(guest_pt[PTE64_INDEX(fault_addr)]);;
    pte64_t * shadow_pte = (pte64_t *)&(shadow_pt[PTE64_INDEX(fault_addr)]);
    addr_t guest_pa = BASE_TO_PAGE_ADDR((addr_t)(guest_pte->page_base_addr)) +  PAGE_OFFSET(fault_addr);
    //  struct shadow_page_state * state = &(info->shdw_pg_state);

    PrintDebug("Handling PTE fault\n");

    struct v3_shadow_region * shdw_reg =  v3_get_shadow_region(info, guest_pa);



    if (shdw_reg == NULL) {
	// Inject a machine check in the guest
	PrintError("Invalid Guest Address in page table (0x%p)\n", (void *)guest_pa);
	v3_raise_exception(info, MC_EXCEPTION);
	return 0;
    }

    // Check the guest page permissions
    guest_pte_access = v3_can_access_pte64(guest_pt, fault_addr, error_code);

    // Check the shadow page permissions
    shadow_pte_access = v3_can_access_pte64(shadow_pt, fault_addr, error_code);

    /* Was the page fault caused by the Guest's page tables? */
    if (is_guest_pf(guest_pte_access, shadow_pte_access) == 1) {

	PrintDebug("Access error injecting pf to guest (guest access error=%d) (pf error code=%d)\n", 
		   guest_pte_access, *(uint_t*)&error_code);    

	if (inject_guest_pf(info, fault_addr, error_code) == -1) {
	    PrintError("Could not inject guest page fault\n");
	    return -1;
	}

	return 0; 
    }

 
    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;
    }


    if (shadow_pte_access == PT_ACCESS_NOT_PRESENT) {
	// Page Table Entry Not Present
	PrintDebug("guest_pa =%p\n", (void *)guest_pa);

	if ((shdw_reg->host_type == SHDW_REGION_ALLOCATED) ||
	    (shdw_reg->host_type == SHDW_REGION_WRITE_HOOK)) {
	    addr_t shadow_pa = v3_get_shadow_addr(shdw_reg, guest_pa);
      
	    shadow_pte->page_base_addr = PAGE_BASE_ADDR(shadow_pa);
      
	    shadow_pte->present = guest_pte->present;
	    shadow_pte->user_page = guest_pte->user_page;
      
	    //set according to VMM policy
	    shadow_pte->write_through = guest_pte->write_through;
	    shadow_pte->cache_disable = guest_pte->cache_disable;
	    shadow_pte->global_page = guest_pte->global_page;
	    //
      
	    guest_pte->accessed = 1;
      
	    if (guest_pte->dirty == 1) {
		shadow_pte->writable = guest_pte->writable;
	    } else if ((guest_pte->dirty == 0) && (error_code.write == 1)) {
		shadow_pte->writable = guest_pte->writable;
		guest_pte->dirty = 1;
	    } else if ((guest_pte->dirty == 0) && (error_code.write == 0)) {
		shadow_pte->writable = 0;
	    }


	    // Write hooks trump all, and are set Read Only
	    if (shdw_reg->host_type == SHDW_REGION_WRITE_HOOK) {
		shadow_pte->writable = 0;
	    }

	} else {
	    // Page fault handled by hook functions

	    if (v3_handle_mem_full_hook(info, fault_addr, guest_pa, shdw_reg, error_code) == -1) {
		PrintError("Special Page fault handler returned error for address: %p\n",  (void *)fault_addr);
		return -1;
	    }
	}
    } else if (shadow_pte_access == PT_ACCESS_WRITE_ERROR) {
	guest_pte->dirty = 1;

	if (shdw_reg->host_type == SHDW_REGION_WRITE_HOOK) {
	    if (v3_handle_mem_wr_hook(info, fault_addr, guest_pa, shdw_reg, error_code) == -1) {
		PrintError("Special Page fault handler returned error for address: %p\n",  (void *)fault_addr);
		return -1;
	    }
	} else {
	    PrintDebug("Shadow PTE Write Error\n");
	    shadow_pte->writable = guest_pte->writable;
	}


	return 0;

    } else {
	// Inject page fault into the guest	
	if (inject_guest_pf(info, fault_addr, error_code) == -1) {
	    PrintError("Could not inject guest page fault\n");
	    return -1;
	}
	PrintError("PTE Page fault fell through... Not sure if this should ever happen\n");
	PrintError("Manual Says to inject page fault into guest\n");
	return -1;
    }

    return 0;
}



static int handle_2MB_shadow_pagefault_64(struct guest_info * info, 
					  addr_t fault_addr, pf_error_t error_code, 
					  pte64_t * shadow_pt, pde64_2MB_t * large_guest_pde) 
{
    pt_access_status_t shadow_pte_access = v3_can_access_pte64(shadow_pt, fault_addr, error_code);
    pte64_t * shadow_pte = (pte64_t *)&(shadow_pt[PTE64_INDEX(fault_addr)]);
    addr_t guest_fault_pa = BASE_TO_PAGE_ADDR_2MB(large_guest_pde->page_base_addr) + PAGE_OFFSET_2MB(fault_addr);
    //  struct shadow_page_state * state = &(info->shdw_pg_state);

    PrintDebug("Handling 2MB fault (guest_fault_pa=%p) (error_code=%x)\n", (void *)guest_fault_pa, *(uint_t*)&error_code);
    PrintDebug("ShadowPT=%p, LargeGuestPDE=%p\n", shadow_pt, large_guest_pde);

    struct v3_shadow_region * shdw_reg = v3_get_shadow_region(info, guest_fault_pa);

 
    if (shdw_reg == NULL) {
	// Inject a machine check in the guest
	PrintError("Invalid Guest Address in page table (0x%p)\n", (void *)guest_fault_pa);
	v3_raise_exception(info, MC_EXCEPTION);
	return 0;
    }

    if (shadow_pte_access == PT_ACCESS_OK) {
	// Inconsistent state...
	// Guest Re-Entry will flush tables and everything should now workd
	PrintDebug("Inconsistent state... Guest re-entry should flush tlb\n");
	//PrintHostPageTree(info, fault_addr, info->ctrl_regs.cr3);
	return 0;
    }

  
    if (shadow_pte_access == PT_ACCESS_NOT_PRESENT) {
	// Get the guest physical address of the fault

	if ((shdw_reg->host_type == SHDW_REGION_ALLOCATED) || 
	    (shdw_reg->host_type == SHDW_REGION_WRITE_HOOK)) {
	    addr_t shadow_pa = v3_get_shadow_addr(shdw_reg, guest_fault_pa);

	    shadow_pte->page_base_addr = PAGE_BASE_ADDR(shadow_pa);

	    shadow_pte->present = 1;

	    /* We are assuming that the PDE entry has precedence
	     * so the Shadow PDE will mirror the guest PDE settings, 
	     * and we don't have to worry about them here
	     * Allow everything
	     */
	    shadow_pte->user_page = 1;

	    if (shdw_reg->host_type == SHDW_REGION_WRITE_HOOK) {
		shadow_pte->writable = 0;
	    } else {
		shadow_pte->writable = 1;
	    }

	    //set according to VMM policy
	    shadow_pte->write_through = large_guest_pde->write_through;
	    shadow_pte->cache_disable = large_guest_pde->cache_disable;
	    shadow_pte->global_page = large_guest_pde->global_page;
	    //
      
	} else {
	    if (v3_handle_mem_full_hook(info, fault_addr, guest_fault_pa, shdw_reg, error_code) == -1) {
		PrintError("Special Page Fault handler returned error for address: %p\n", (void *)fault_addr);
		return -1;
	    }
	}
    } else if (shadow_pte_access == PT_ACCESS_WRITE_ERROR) {

	if (shdw_reg->host_type == SHDW_REGION_WRITE_HOOK) {

	    if (v3_handle_mem_wr_hook(info, fault_addr, guest_fault_pa, shdw_reg, error_code) == -1) {
		PrintError("Special Page Fault handler returned error for address: %p\n", (void *)fault_addr);
		return -1;
	    }
	}

    } else {
	PrintError("Error in large page fault handler...\n");
	PrintError("This case should have been handled at the top level handler\n");
	return -1;
    }

    //  PrintHostPageTree(info, fault_addr, info->ctrl_regs.cr3);
    PrintDebug("Returning from large page fault handler\n");
    return 0;
}




static int invalidation_cb_64(struct guest_info * info, page_type_t type, 
			      addr_t vaddr, addr_t page_ptr, addr_t page_pa, 
			      void * private_data) {

    switch (type) {
	case PAGE_PML464:
	    {    
		pml4e64_t * pml = (pml4e64_t *)page_ptr;

		if (pml[PML4E64_INDEX(vaddr)].present == 0) {
		    return 1;
		}
		return 0;
	    }
	case PAGE_PDP64:
	    {
		pdpe64_t * pdp = (pdpe64_t *)page_ptr;
		pdpe64_t * pdpe = &(pdp[PDPE64_INDEX(vaddr)]);

		if (pdpe->present == 0) {
		    return 1;
		}
     
		if (pdpe->vmm_info == V3_LARGE_PG) {
		    PrintError("1 Gigabyte pages not supported\n");
		    return -1;

		    pdpe->present = 0;
		    return 1;
		}

		return 0;
	    }
	case PAGE_PD64:
	    {
		pde64_t * pd = (pde64_t *)page_ptr;
		pde64_t * pde = &(pd[PDE64_INDEX(vaddr)]);

		if (pde->present == 0) {
		    return 1;
		}
      
		if (pde->vmm_info == V3_LARGE_PG) {
		    pde->present = 0;
		    return 1;
		}

		return 0;
	    }
	case PAGE_PT64:
	    {
		pte64_t * pt = (pte64_t *)page_ptr;

		pt[PTE64_INDEX(vaddr)].present = 0;

		return 1;
	    }
	default:
	    PrintError("Invalid Page Type\n");
	    return -1;

    }

    // should not get here
    PrintError("Should not get here....\n");
    return -1;
}


static inline int handle_shadow_invlpg_64(struct guest_info * info, addr_t vaddr) {
    PrintDebug("INVLPG64 - %p\n",(void*)vaddr);

    int ret =  v3_drill_host_pt_64(info, info->ctrl_regs.cr3, vaddr, invalidation_cb_64, NULL);
    if (ret == -1) {
	PrintError("Page table drill returned error.... \n");
	PrintHostPageTree(info, vaddr, info->ctrl_regs.cr3);
    }

    return (ret == -1) ? -1 : 0; 
}