#ifndef _LGUEST_H
  #define _LGUEST_H
  
  #ifndef __ASSEMBLY__
  #include <linux/types.h>
  #include <linux/init.h>
  #include <linux/stringify.h>
  #include <linux/lguest.h>
  #include <linux/lguest_launcher.h>
  #include <linux/wait.h>
  #include <linux/hrtimer.h>
  #include <linux/err.h>
  #include <linux/slab.h>
  
  #include <asm/lguest.h>
  
  struct pgdir {
  	unsigned long gpgdir;
  	bool switcher_mapped;
  	int last_host_cpu;
  	pgd_t *pgdir;
  };
  
  /* We have two pages shared with guests, per cpu.  */
  struct lguest_pages {
  	/* This is the stack page mapped rw in guest */
  	char spare[PAGE_SIZE - sizeof(struct lguest_regs)];
  	struct lguest_regs regs;
  
  	/* This is the host state & guest descriptor page, ro in guest */
  	struct lguest_ro_state state;
  } __attribute__((aligned(PAGE_SIZE)));
  
  #define CHANGED_IDT		1
  #define CHANGED_GDT		2
  #define CHANGED_GDT_TLS		4 /* Actually a subset of CHANGED_GDT */
  #define CHANGED_ALL	        3
  
  struct lg_cpu {
  	unsigned int id;
  	struct lguest *lg;
  	struct task_struct *tsk;
  	struct mm_struct *mm; 	/* == tsk->mm, but that becomes NULL on exit */
  
  	u32 cr2;
  	int ts;
  	u32 esp1;
  	u16 ss1;
  
  	/* Bitmap of what has changed: see CHANGED_* above. */
  	int changed;
  
  	unsigned long pending_notify; /* pfn from LHCALL_NOTIFY */
  
  	/* At end of a page shared mapped over lguest_pages in guest. */
  	unsigned long regs_page;
  	struct lguest_regs *regs;
  
  	struct lguest_pages *last_pages;
  
  	/* Initialization mode: linear map everything. */
  	bool linear_pages;
  	int cpu_pgd; /* Which pgd this cpu is currently using */
  
  	/* If a hypercall was asked for, this points to the arguments. */
  	struct hcall_args *hcall;
  	u32 next_hcall;
  
  	/* Virtual clock device */
  	struct hrtimer hrt;
  
  	/* Did the Guest tell us to halt? */
  	int halted;
  
  	/* Pending virtual interrupts */
  	DECLARE_BITMAP(irqs_pending, LGUEST_IRQS);
  
  	struct lg_cpu_arch arch;
  };
  
  struct lg_eventfd {
  	unsigned long addr;
  	struct eventfd_ctx *event;
  };
  
  struct lg_eventfd_map {
  	unsigned int num;
  	struct lg_eventfd map[];
  };
  
  /* The private info the thread maintains about the guest. */
  struct lguest {
  	struct lguest_data __user *lguest_data;
  	struct lg_cpu cpus[NR_CPUS];
  	unsigned int nr_cpus;
  
  	u32 pfn_limit;
  
  	/*
  	 * This provides the offset to the base of guest-physical memory in the
  	 * Launcher.
  	 */
  	void __user *mem_base;
  	unsigned long kernel_address;
  
  	struct pgdir pgdirs[4];
  
  	unsigned long noirq_start, noirq_end;
  
  	unsigned int stack_pages;
  	u32 tsc_khz;
  
  	struct lg_eventfd_map *eventfds;
  
  	/* Dead? */
  	const char *dead;
  };
  
  extern struct mutex lguest_lock;
  
  /* core.c: */
  bool lguest_address_ok(const struct lguest *lg,
  		       unsigned long addr, unsigned long len);
  void __lgread(struct lg_cpu *, void *, unsigned long, unsigned);
  void __lgwrite(struct lg_cpu *, unsigned long, const void *, unsigned);
  extern struct page **lg_switcher_pages;
  
  /*H:035
   * Using memory-copy operations like that is usually inconvient, so we
   * have the following helper macros which read and write a specific type (often
   * an unsigned long).
   *
   * This reads into a variable of the given type then returns that.
   */
  #define lgread(cpu, addr, type)						\
  	({ type _v; __lgread((cpu), &_v, (addr), sizeof(_v)); _v; })
  
  /* This checks that the variable is of the given type, then writes it out. */
  #define lgwrite(cpu, addr, type, val)				\
  	do {							\
  		typecheck(type, val);				\
  		__lgwrite((cpu), (addr), &(val), sizeof(val));	\
  	} while(0)
  /* (end of memory access helper routines) :*/
  
  int run_guest(struct lg_cpu *cpu, unsigned long __user *user);
  
  /*
   * Helper macros to obtain the first 12 or the last 20 bits, this is only the
   * first step in the migration to the kernel types.  pte_pfn is already defined
   * in the kernel.
   */
  #define pgd_flags(x)	(pgd_val(x) & ~PAGE_MASK)
  #define pgd_pfn(x)	(pgd_val(x) >> PAGE_SHIFT)
  #define pmd_flags(x)    (pmd_val(x) & ~PAGE_MASK)
  #define pmd_pfn(x)	(pmd_val(x) >> PAGE_SHIFT)
  
  /* interrupts_and_traps.c: */
  unsigned int interrupt_pending(struct lg_cpu *cpu, bool *more);
  void try_deliver_interrupt(struct lg_cpu *cpu, unsigned int irq, bool more);
  void set_interrupt(struct lg_cpu *cpu, unsigned int irq);
  bool deliver_trap(struct lg_cpu *cpu, unsigned int num);
  void load_guest_idt_entry(struct lg_cpu *cpu, unsigned int i,
  			  u32 low, u32 hi);
  void guest_set_stack(struct lg_cpu *cpu, u32 seg, u32 esp, unsigned int pages);
  void pin_stack_pages(struct lg_cpu *cpu);
  void setup_default_idt_entries(struct lguest_ro_state *state,
  			       const unsigned long *def);
  void copy_traps(const struct lg_cpu *cpu, struct desc_struct *idt,
  		const unsigned long *def);
  void guest_set_clockevent(struct lg_cpu *cpu, unsigned long delta);
  bool send_notify_to_eventfd(struct lg_cpu *cpu);
  void init_clockdev(struct lg_cpu *cpu);
  bool check_syscall_vector(struct lguest *lg);
  int init_interrupts(void);
  void free_interrupts(void);
  
  /* segments.c: */
  void setup_default_gdt_entries(struct lguest_ro_state *state);
  void setup_guest_gdt(struct lg_cpu *cpu);
  void load_guest_gdt_entry(struct lg_cpu *cpu, unsigned int i,
  			  u32 low, u32 hi);
  void guest_load_tls(struct lg_cpu *cpu, unsigned long tls_array);
  void copy_gdt(const struct lg_cpu *cpu, struct desc_struct *gdt);
  void copy_gdt_tls(const struct lg_cpu *cpu, struct desc_struct *gdt);
  
  /* page_tables.c: */
  int init_guest_pagetable(struct lguest *lg);
  void free_guest_pagetable(struct lguest *lg);
  void guest_new_pagetable(struct lg_cpu *cpu, unsigned long pgtable);
  void guest_set_pgd(struct lguest *lg, unsigned long gpgdir, u32 i);
  #ifdef CONFIG_X86_PAE
  void guest_set_pmd(struct lguest *lg, unsigned long gpgdir, u32 i);
  #endif
  void guest_pagetable_clear_all(struct lg_cpu *cpu);
  void guest_pagetable_flush_user(struct lg_cpu *cpu);
  void guest_set_pte(struct lg_cpu *cpu, unsigned long gpgdir,
  		   unsigned long vaddr, pte_t val);
  void map_switcher_in_guest(struct lg_cpu *cpu, struct lguest_pages *pages);
  bool demand_page(struct lg_cpu *cpu, unsigned long cr2, int errcode);
  void pin_page(struct lg_cpu *cpu, unsigned long vaddr);
  unsigned long guest_pa(struct lg_cpu *cpu, unsigned long vaddr);
  void page_table_guest_data_init(struct lg_cpu *cpu);
  
  /* <arch>/core.c: */
  void lguest_arch_host_init(void);
  void lguest_arch_host_fini(void);
  void lguest_arch_run_guest(struct lg_cpu *cpu);
  void lguest_arch_handle_trap(struct lg_cpu *cpu);
  int lguest_arch_init_hypercalls(struct lg_cpu *cpu);
  int lguest_arch_do_hcall(struct lg_cpu *cpu, struct hcall_args *args);
  void lguest_arch_setup_regs(struct lg_cpu *cpu, unsigned long start);
  
  /* <arch>/switcher.S: */
  extern char start_switcher_text[], end_switcher_text[], switch_to_guest[];
  
  /* lguest_user.c: */
  int lguest_device_init(void);
  void lguest_device_remove(void);
  
  /* hypercalls.c: */
  void do_hypercalls(struct lg_cpu *cpu);
  void write_timestamp(struct lg_cpu *cpu);
  
  /*L:035
   * Let's step aside for the moment, to study one important routine that's used
   * widely in the Host code.
   *
   * There are many cases where the Guest can do something invalid, like pass crap
   * to a hypercall.  Since only the Guest kernel can make hypercalls, it's quite
   * acceptable to simply terminate the Guest and give the Launcher a nicely
   * formatted reason.  It's also simpler for the Guest itself, which doesn't
   * need to check most hypercalls for "success"; if you're still running, it
   * succeeded.
   *
   * Once this is called, the Guest will never run again, so most Host code can
   * call this then continue as if nothing had happened.  This means many
   * functions don't have to explicitly return an error code, which keeps the
   * code simple.
   *
   * It also means that this can be called more than once: only the first one is
   * remembered.  The only trick is that we still need to kill the Guest even if
   * we can't allocate memory to store the reason.  Linux has a neat way of
   * packing error codes into invalid pointers, so we use that here.
   *
   * Like any macro which uses an "if", it is safely wrapped in a run-once "do {
   * } while(0)".
   */
  #define kill_guest(cpu, fmt...)					\
  do {								\
  	if (!(cpu)->lg->dead) {					\
  		(cpu)->lg->dead = kasprintf(GFP_ATOMIC, fmt);	\
  		if (!(cpu)->lg->dead)				\
  			(cpu)->lg->dead = ERR_PTR(-ENOMEM);	\
  	}							\
  } while(0)
  /* (End of aside) :*/
  
  #endif	/* __ASSEMBLY__ */
  #endif	/* _LGUEST_H */