/******************************************************************************
 * hypercall.h
 *
 * Copyright (C) 2006, Virtual Iron Software, Inc.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
 * Place - Suite 330, Boston, MA 02111-1307 USA.
 *
 */

#include <linux/version.h>
#include <asm/hypervisor.h>
#include <xen/interface/xen.h>

static inline int
check_amd(void)
{
        char id[12];

        __asm__ __volatile__(
                "cpuid"
                : "=b" (*(int *)(&id[0])),
                  "=c" (*(int *)(&id[8])),
                  "=d" (*(int *)(&id[4]))
                : "a" (0)
        );
        return __builtin_memcmp(id, "AuthenticAMD", 12) == 0;
}

#define VMCALL_INSTR	0x0f,0x01,0xc1
#define VMMCALL_INSTR	0x0f,0x01,0xd6

#define NR_hypercalls (PAGE_SIZE/32)

static inline void hypercall_page_init(void *hypercall_page)
{
    int i;
    char *p;
    char vmcall[3] = { VMCALL_INSTR };
    char vmmcall[3] = { VMMCALL_INSTR };
    int amd = check_amd();

    for ( i = 0; i < NR_hypercalls; i++ )
    {
	p = (char *)(hypercall_page + (i * 32));
	/*
	 * This call sequence works for 32-bit and 64-bit guests.
	 */
	memset(p, 0xcc, 32);
	*(u8  *)(p+ 0) = 0xb8;		/* mov $<i>,%eax */
	*(u32 *)(p+ 1) = i;
	if (amd) {
	    *(u8  *)(p+ 5) = vmmcall[0];
	    *(u8  *)(p+ 6) = vmmcall[1];
	    *(u8  *)(p+ 7) = vmmcall[2];
	} else {
	    *(u8  *)(p+ 5) = vmcall[0];
	    *(u8  *)(p+ 6) = vmcall[1];
	    *(u8  *)(p+ 7) = vmcall[2];
	}
	*(u8  *)(p+ 8) = 0xc3;		/* ret */
    }
}