/* 
 * 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>

#ifndef DEBUG_SHADOW_PAGING
#undef PrintDebug
#define PrintDebug(fmt, args...)
#endif


/*** 
 ***  There be dragons
 ***/


struct guest_table {
  addr_t cr3;
  struct list_head link;
};


struct backptr {
  addr_t ptr;
  struct list_head link;
};


struct shadow_page_data {
  addr_t ptr;
  addr_t guest_addr; 

  struct list_head backptrs;
  struct list_head guest_tables;
};




//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);


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);



static uint_t pte_hash_fn(addr_t key) {
  return hash_long(key, 32);
}

static int pte_equals(addr_t key1, addr_t key2) {
  return (key1 == key2);
}

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"



int v3_init_shadow_page_state(struct guest_info * info) {
  struct shadow_page_state * state = &(info->shdw_pg_state);
  
  state->guest_cr3 = 0;
  state->guest_cr0 = 0;

  state->cached_ptes = NULL;

  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 * 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;
}


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_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

#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

    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;
    }
  } else {
    PrintError("Invalid Memory mode\n");
    return -1;
  }
}



static addr_t create_new_shadow_pt() {
  void * host_pde = 0;

  host_pde = V3_VAddr(V3_AllocPages(1));
  memset(host_pde, 0, PAGE_SIZE);

  return (addr_t)host_pde;
}


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);
}


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

     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;
    }

    // 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)
{
  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++;
  }
    
    
  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;

  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;
    }
  
  info->rip += index;
  
  return 0;
}