/******************************************************************************
 * x86_emulate.h
 *
 * Generic x86 (32-bit and 64-bit) instruction decoder and emulator.
 *
 * Copyright (c) 2005 Keir Fraser
 *
 * From: xen-unstable 10676:af9809f51f81a3c43f276f00c81a52ef558afda4
 */

#ifndef _ASM_X86_KVM_X86_EMULATE_H
#define _ASM_X86_KVM_X86_EMULATE_H

#include <asm/desc_defs.h>

struct x86_emulate_ctxt;

struct x86_exception {
        u8 vector;
        bool error_code_valid;
        u16 error_code;
        bool nested_page_fault;
        u64 address; /* cr2 or nested page fault gpa */
};

/*
 * x86_emulate_ops:
 *
 * These operations represent the instruction emulator's interface to memory.
 * There are two categories of operation: those that act on ordinary memory
 * regions (*_std), and those that act on memory regions known to require
 * special treatment or emulation (*_emulated).
 *
 * The emulator assumes that an instruction accesses only one 'emulated memory'
 * location, that this location is the given linear faulting address (cr2), and
 * that this is one of the instruction's data operands. Instruction fetches and
 * stack operations are assumed never to access emulated memory. The emulator
 * automatically deduces which operand of a string-move operation is accessing
 * emulated memory, and assumes that the other operand accesses normal memory.
 *
 * NOTES:
 *  1. The emulator isn't very smart about emulated vs. standard memory.
 *     'Emulated memory' access addresses should be checked for sanity.
 *     'Normal memory' accesses may fault, and the caller must arrange to
 *     detect and handle reentrancy into the emulator via recursive faults.
 *     Accesses may be unaligned and may cross page boundaries.
 *  2. If the access fails (cannot emulate, or a standard access faults) then
 *     it is up to the memop to propagate the fault to the guest VM via
 *     some out-of-band mechanism, unknown to the emulator. The memop signals
 *     failure by returning X86EMUL_PROPAGATE_FAULT to the emulator, which will
 *     then immediately bail.
 *  3. Valid access sizes are 1, 2, 4 and 8 bytes. On x86/32 systems only
 *     cmpxchg8b_emulated need support 8-byte accesses.
 *  4. The emulator cannot handle 64-bit mode emulation on an x86/32 system.
 */
/* Access completed successfully: continue emulation as normal. */
#define X86EMUL_CONTINUE        0
/* Access is unhandleable: bail from emulation and return error to caller. */
#define X86EMUL_UNHANDLEABLE    1
/* Terminate emulation but return success to the caller. */
#define X86EMUL_PROPAGATE_FAULT 2 /* propagate a generated fault to guest */
#define X86EMUL_RETRY_INSTR     3 /* retry the instruction for some reason */
#define X86EMUL_CMPXCHG_FAILED  4 /* cmpxchg did not see expected value */
#define X86EMUL_IO_NEEDED       5 /* IO is needed to complete emulation */

struct x86_emulate_ops {
        /*
         * read_std: Read bytes of standard (non-emulated/special) memory.
         *           Used for descriptor reading.
         *  @addr:  [IN ] Linear address from which to read.
         *  @val:   [OUT] Value read from memory, zero-extended to 'u_long'.
         *  @bytes: [IN ] Number of bytes to read from memory.
         */
        int (*read_std)(unsigned long addr, void *val,
                        unsigned int bytes, struct kvm_vcpu *vcpu,
                        struct x86_exception *fault);

        /*
         * write_std: Write bytes of standard (non-emulated/special) memory.
         *            Used for descriptor writing.
         *  @addr:  [IN ] Linear address to which to write.
         *  @val:   [OUT] Value write to memory, zero-extended to 'u_long'.
         *  @bytes: [IN ] Number of bytes to write to memory.
         */
        int (*write_std)(unsigned long addr, void *val,
                         unsigned int bytes, struct kvm_vcpu *vcpu,
                         struct x86_exception *fault);
        /*
         * fetch: Read bytes of standard (non-emulated/special) memory.
         *        Used for instruction fetch.
         *  @addr:  [IN ] Linear address from which to read.
         *  @val:   [OUT] Value read from memory, zero-extended to 'u_long'.
         *  @bytes: [IN ] Number of bytes to read from memory.
         */
        int (*fetch)(unsigned long addr, void *val,
                     unsigned int bytes, struct kvm_vcpu *vcpu,
                     struct x86_exception *fault);

        /*
         * read_emulated: Read bytes from emulated/special memory area.
         *  @addr:  [IN ] Linear address from which to read.
         *  @val:   [OUT] Value read from memory, zero-extended to 'u_long'.
         *  @bytes: [IN ] Number of bytes to read from memory.
         */
        int (*read_emulated)(unsigned long addr,
                             void *val,
                             unsigned int bytes,
                             struct x86_exception *fault,
                             struct kvm_vcpu *vcpu);

        /*
         * write_emulated: Write bytes to emulated/special memory area.
         *  @addr:  [IN ] Linear address to which to write.
         *  @val:   [IN ] Value to write to memory (low-order bytes used as
         *                required).
         *  @bytes: [IN ] Number of bytes to write to memory.
         */
        int (*write_emulated)(unsigned long addr,
                              const void *val,
                              unsigned int bytes,
                              struct x86_exception *fault,
                              struct kvm_vcpu *vcpu);

        /*
         * cmpxchg_emulated: Emulate an atomic (LOCKed) CMPXCHG operation on an
         *                   emulated/special memory area.
         *  @addr:  [IN ] Linear address to access.
         *  @old:   [IN ] Value expected to be current at @addr.
         *  @new:   [IN ] Value to write to @addr.
         *  @bytes: [IN ] Number of bytes to access using CMPXCHG.
         */
        int (*cmpxchg_emulated)(unsigned long addr,
                                const void *old,
                                const void *new,
                                unsigned int bytes,
                                struct x86_exception *fault,
                                struct kvm_vcpu *vcpu);

        int (*pio_in_emulated)(int size, unsigned short port, void *val,
                               unsigned int count, struct kvm_vcpu *vcpu);

        int (*pio_out_emulated)(int size, unsigned short port, const void *val,
                                unsigned int count, struct kvm_vcpu *vcpu);

        bool (*get_cached_descriptor)(struct desc_struct *desc,
                                      int seg, struct kvm_vcpu *vcpu);
        void (*set_cached_descriptor)(struct desc_struct *desc,
                                      int seg, struct kvm_vcpu *vcpu);
        u16 (*get_segment_selector)(int seg, struct kvm_vcpu *vcpu);
        void (*set_segment_selector)(u16 sel, int seg, struct kvm_vcpu *vcpu);
        unsigned long (*get_cached_segment_base)(int seg, struct kvm_vcpu *vcpu);
        void (*get_gdt)(struct desc_ptr *dt, struct kvm_vcpu *vcpu);
        void (*get_idt)(struct desc_ptr *dt, struct kvm_vcpu *vcpu);
        ulong (*get_cr)(int cr, struct kvm_vcpu *vcpu);
        int (*set_cr)(int cr, ulong val, struct kvm_vcpu *vcpu);
        int (*cpl)(struct kvm_vcpu *vcpu);
        int (*get_dr)(int dr, unsigned long *dest, struct kvm_vcpu *vcpu);
        int (*set_dr)(int dr, unsigned long value, struct kvm_vcpu *vcpu);
        int (*set_msr)(struct kvm_vcpu *vcpu, u32 msr_index, u64 data);
        int (*get_msr)(struct kvm_vcpu *vcpu, u32 msr_index, u64 *pdata);
};

/* Type, address-of, and value of an instruction's operand. */
struct operand {
        enum { OP_REG, OP_MEM, OP_IMM, OP_NONE } type;
        unsigned int bytes;
        union {
                unsigned long orig_val;
                u64 orig_val64;
        };
        union {
                unsigned long *reg;
                struct segmented_address {
                        ulong ea;
                        unsigned seg;
                } mem;
        } addr;
        union {
                unsigned long val;
                u64 val64;
                char valptr[sizeof(unsigned long) + 2];
        };
};

struct fetch_cache {
        u8 data[15];
        unsigned long start;
        unsigned long end;
};

struct read_cache {
        u8 data[1024];
        unsigned long pos;
        unsigned long end;
};

struct decode_cache {
        u8 twobyte;
        u8 b;
        u8 lock_prefix;
        u8 rep_prefix;
        u8 op_bytes;
        u8 ad_bytes;
        u8 rex_prefix;
        struct operand src;
        struct operand src2;
        struct operand dst;
        bool has_seg_override;
        u8 seg_override;
        unsigned int d;
        int (*execute)(struct x86_emulate_ctxt *ctxt);
        unsigned long regs[NR_VCPU_REGS];
        unsigned long eip;
        /* modrm */
        u8 modrm;
        u8 modrm_mod;
        u8 modrm_reg;
        u8 modrm_rm;
        u8 modrm_seg;
        bool rip_relative;
        struct fetch_cache fetch;
        struct read_cache io_read;
        struct read_cache mem_read;
};

struct x86_emulate_ctxt {
        struct x86_emulate_ops *ops;

        /* Register state before/after emulation. */
        struct kvm_vcpu *vcpu;

        unsigned long eflags;
        unsigned long eip; /* eip before instruction emulation */
        /* Emulated execution mode, represented by an X86EMUL_MODE value. */
        int mode;
        u32 cs_base;

        /* interruptibility state, as a result of execution of STI or MOV SS */
        int interruptibility;

        bool perm_ok; /* do not check permissions if true */

        bool have_exception;
        struct x86_exception exception;

        /* decode cache */
        struct decode_cache decode;
};

/* Repeat String Operation Prefix */
#define REPE_PREFIX     1
#define REPNE_PREFIX    2

/* Execution mode, passed to the emulator. */
#define X86EMUL_MODE_REAL     0 /* Real mode.             */
#define X86EMUL_MODE_VM86     1 /* Virtual 8086 mode.     */
#define X86EMUL_MODE_PROT16   2 /* 16-bit protected mode. */
#define X86EMUL_MODE_PROT32   4 /* 32-bit protected mode. */
#define X86EMUL_MODE_PROT64   8 /* 64-bit (long) mode.    */

/* Host execution mode. */
#if defined(CONFIG_X86_32)
#define X86EMUL_MODE_HOST X86EMUL_MODE_PROT32
#elif defined(CONFIG_X86_64)
#define X86EMUL_MODE_HOST X86EMUL_MODE_PROT64
#endif

int x86_decode_insn(struct x86_emulate_ctxt *ctxt, void *insn, int insn_len);
#define EMULATION_FAILED -1
#define EMULATION_OK 0
#define EMULATION_RESTART 1
int x86_emulate_insn(struct x86_emulate_ctxt *ctxt);
int emulator_task_switch(struct x86_emulate_ctxt *ctxt,
                         u16 tss_selector, int reason,
                         bool has_error_code, u32 error_code);
int emulate_int_real(struct x86_emulate_ctxt *ctxt,
                     struct x86_emulate_ops *ops, int irq);
#endif /* _ASM_X86_KVM_X86_EMULATE_H */