    /******************************************************************************
     * xen-x86_64.h
     *
     * Guest OS interface to x86 64-bit Xen.
     *
     * Permission is hereby granted, free of charge, to any person obtaining a copy
     * of this software and associated documentation files (the "Software"), to
     * deal in the Software without restriction, including without limitation the
     * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
     * sell copies of the Software, and to permit persons to whom the Software is
     * furnished to do so, subject to the following conditions:
     *
     * The above copyright notice and this permission notice shall be included in
     * all copies or substantial portions of the Software.
     *
     * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
     * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
     * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
     * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
     * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
     * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
     * DEALINGS IN THE SOFTWARE.
     *
     * Copyright (c) 2004-2006, K A Fraser
     */

    #ifndef __XEN_PUBLIC_ARCH_X86_XEN_X86_64_H__
    #define __XEN_PUBLIC_ARCH_X86_XEN_X86_64_H__

    /*
     * Hypercall interface:
     *  Input:  %rdi, %rsi, %rdx, %r10, %r8, %r9 (arguments 1-6)
     *  Output: %rax
     * Access is via hypercall page (set up by guest loader or via a Xen MSR):
     *  call hypercall_page + hypercall-number * 32
     * Clobbered: argument registers (e.g., 2-arg hypercall clobbers %rdi,%rsi)
     */

    /*
     * 64-bit segment selectors
     * These flat segments are in the Xen-private section of every GDT. Since these
     * are also present in the initial GDT, many OSes will be able to avoid
     * installing their own GDT.
     */

    #define FLAT_RING3_CS32 0xe023  /* GDT index 260 */
    #define FLAT_RING3_CS64 0xe033  /* GDT index 261 */
    #define FLAT_RING3_DS32 0xe02b  /* GDT index 262 */
    #define FLAT_RING3_DS64 0x0000  /* NULL selector */
    #define FLAT_RING3_SS32 0xe02b  /* GDT index 262 */
    #define FLAT_RING3_SS64 0xe02b  /* GDT index 262 */

    #define FLAT_KERNEL_DS64 FLAT_RING3_DS64
    #define FLAT_KERNEL_DS32 FLAT_RING3_DS32
    #define FLAT_KERNEL_DS   FLAT_KERNEL_DS64
    #define FLAT_KERNEL_CS64 FLAT_RING3_CS64
    #define FLAT_KERNEL_CS32 FLAT_RING3_CS32
    #define FLAT_KERNEL_CS   FLAT_KERNEL_CS64
    #define FLAT_KERNEL_SS64 FLAT_RING3_SS64
    #define FLAT_KERNEL_SS32 FLAT_RING3_SS32
    #define FLAT_KERNEL_SS   FLAT_KERNEL_SS64

    #define FLAT_USER_DS64 FLAT_RING3_DS64
    #define FLAT_USER_DS32 FLAT_RING3_DS32
    #define FLAT_USER_DS   FLAT_USER_DS64
    #define FLAT_USER_CS64 FLAT_RING3_CS64
    #define FLAT_USER_CS32 FLAT_RING3_CS32
    #define FLAT_USER_CS   FLAT_USER_CS64
    #define FLAT_USER_SS64 FLAT_RING3_SS64
    #define FLAT_USER_SS32 FLAT_RING3_SS32
    #define FLAT_USER_SS   FLAT_USER_SS64

    #define __HYPERVISOR_VIRT_START 0xFFFF800000000000
    #define __HYPERVISOR_VIRT_END   0xFFFF880000000000
    #define __MACH2PHYS_VIRT_START  0xFFFF800000000000
    #define __MACH2PHYS_VIRT_END    0xFFFF804000000000

    #ifndef HYPERVISOR_VIRT_START
    #define HYPERVISOR_VIRT_START xen_mk_ulong(__HYPERVISOR_VIRT_START)
    #define HYPERVISOR_VIRT_END   xen_mk_ulong(__HYPERVISOR_VIRT_END)
    #endif

    #define MACH2PHYS_VIRT_START  xen_mk_ulong(__MACH2PHYS_VIRT_START)
    #define MACH2PHYS_VIRT_END    xen_mk_ulong(__MACH2PHYS_VIRT_END)
    #define MACH2PHYS_NR_ENTRIES  ((MACH2PHYS_VIRT_END-MACH2PHYS_VIRT_START)>>3)
    #ifndef machine_to_phys_mapping
    #define machine_to_phys_mapping ((unsigned long *)HYPERVISOR_VIRT_START)
    #endif

    /*
     * int HYPERVISOR_set_segment_base(unsigned int which, unsigned long base)
     *  @which == SEGBASE_*  ;  @base == 64-bit base address
     * Returns 0 on success.
     */
    #define SEGBASE_FS          0
    #define SEGBASE_GS_USER     1
    #define SEGBASE_GS_KERNEL   2
    #define SEGBASE_GS_USER_SEL 3 /* Set user %gs specified in base[15:0] */

    /*
     * int HYPERVISOR_iret(void)
     * All arguments are on the kernel stack, in the following format.
     * Never returns if successful. Current kernel context is lost.
     * The saved CS is mapped as follows:
     *   RING0 -> RING3 kernel mode.
     *   RING1 -> RING3 kernel mode.
     *   RING2 -> RING3 kernel mode.
     *   RING3 -> RING3 user mode.
     * However RING0 indicates that the guest kernel should return to iteself
     * directly with
     *      orb   $3,1*8(%rsp)
     *      iretq
     * If flags contains VGCF_in_syscall:
     *   Restore RAX, RIP, RFLAGS, RSP.
     *   Discard R11, RCX, CS, SS.
     * Otherwise:
     *   Restore RAX, R11, RCX, CS:RIP, RFLAGS, SS:RSP.
     * All other registers are saved on hypercall entry and restored to user.
     */
    /* Guest exited in SYSCALL context? Return to guest with SYSRET? */
    #define _VGCF_in_syscall 8
    #define VGCF_in_syscall  (1<<_VGCF_in_syscall)
    #define VGCF_IN_SYSCALL  VGCF_in_syscall

    #ifndef __ASSEMBLY__

    struct iret_context {
        /* Top of stack (%rsp at point of hypercall). */
        uint64_t rax, r11, rcx, flags, rip, cs, rflags, rsp, ss;
        /* Bottom of iret stack frame. */
    };

    #if defined(__XEN__) || defined(__XEN_TOOLS__)
    /* Anonymous unions include all permissible names (e.g., al/ah/ax/eax/rax). */
    #define __DECL_REG_LOHI(which) union { \
        uint64_t r ## which ## x; \
        uint32_t e ## which ## x; \
        uint16_t which ## x; \
        struct { \
            uint8_t which ## l; \
            uint8_t which ## h; \
        }; \
    }
    #define __DECL_REG_LO8(name) union { \
        uint64_t r ## name; \
        uint32_t e ## name; \
        uint16_t name; \
        uint8_t name ## l; \
    }
    #define __DECL_REG_LO16(name) union { \
        uint64_t r ## name; \
        uint32_t e ## name; \
        uint16_t name; \
    }
    #define __DECL_REG_HI(num) union { \
        uint64_t r ## num; \
        uint32_t r ## num ## d; \
        uint16_t r ## num ## w; \
        uint8_t r ## num ## b; \
    }
    #elif defined(__GNUC__) && !defined(__STRICT_ANSI__)
    /* Anonymous union includes both 32- and 64-bit names (e.g., eax/rax). */
    #define __DECL_REG(name) union { \
        uint64_t r ## name, e ## name; \
        uint32_t _e ## name; \
    }
    #else
    /* Non-gcc sources must always use the proper 64-bit name (e.g., rax). */
    #define __DECL_REG(name) uint64_t r ## name
    #endif

    #ifndef __DECL_REG_LOHI
    #define __DECL_REG_LOHI(name) __DECL_REG(name ## x)
    #define __DECL_REG_LO8        __DECL_REG
    #define __DECL_REG_LO16       __DECL_REG
    #define __DECL_REG_HI(num)    uint64_t r ## num
    #endif

    struct cpu_user_regs {
        __DECL_REG_HI(15);
        __DECL_REG_HI(14);
        __DECL_REG_HI(13);
        __DECL_REG_HI(12);
        __DECL_REG_LO8(bp);
        __DECL_REG_LOHI(b);
        __DECL_REG_HI(11);
        __DECL_REG_HI(10);
        __DECL_REG_HI(9);
        __DECL_REG_HI(8);
        __DECL_REG_LOHI(a);
        __DECL_REG_LOHI(c);
        __DECL_REG_LOHI(d);
        __DECL_REG_LO8(si);
        __DECL_REG_LO8(di);
        uint32_t error_code;    /* private */
        uint32_t entry_vector;  /* private */
        __DECL_REG_LO16(ip);
        uint16_t cs, _pad0[1];
        uint8_t  saved_upcall_mask;
        uint8_t  _pad1[3];
        __DECL_REG_LO16(flags); /* rflags.IF == !saved_upcall_mask */
        __DECL_REG_LO8(sp);
        uint16_t ss, _pad2[3];
        uint16_t es, _pad3[3];
        uint16_t ds, _pad4[3];
        uint16_t fs, _pad5[3]; /* Non-nul => takes precedence over fs_base.      */
        uint16_t gs, _pad6[3]; /* Non-nul => takes precedence over gs_base_user. */
    };
    typedef struct cpu_user_regs cpu_user_regs_t;
    DEFINE_XEN_GUEST_HANDLE(cpu_user_regs_t);

    #undef __DECL_REG
    #undef __DECL_REG_LOHI
    #undef __DECL_REG_LO8
    #undef __DECL_REG_LO16
    #undef __DECL_REG_HI

    #define xen_pfn_to_cr3(pfn) ((unsigned long)(pfn) << 12)
    #define xen_cr3_to_pfn(cr3) ((unsigned long)(cr3) >> 12)

    struct arch_vcpu_info {
        unsigned long cr2;
        unsigned long pad; /* sizeof(vcpu_info_t) == 64 */
    };
    typedef struct arch_vcpu_info arch_vcpu_info_t;

    typedef unsigned long xen_callback_t;

    #endif /* !__ASSEMBLY__ */

    #endif /* __XEN_PUBLIC_ARCH_X86_XEN_X86_64_H__ */

    /*
     * Local variables:
     * mode: C
     * c-file-style: "BSD"
     * c-basic-offset: 4
     * tab-width: 4
     * indent-tabs-mode: nil
     * End:
     */