rdmsr.h

/*
 *  GRUB  --  GRand Unified Bootloader
 *  Copyright (C) 2019  Free Software Foundation, Inc.
 *
 *  GRUB is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  GRUB is distributed in the hope that 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 GRUB.  If not, see <http://www.gnu.org/licenses/>.
 */

#ifndef GRUB_RDMSR_H
#define GRUB_RDMSR_H 1

/*
 * TODO: Add a general protection exception handler.
 *       Accessing a reserved or unimplemented MSR address results in a GP#.
 */

inline grub_uint64_t
grub_msr_read (grub_uint32_t msr_id)
{
  grub_uint32_t low, high;

  asm volatile ("rdmsr" : "=a" (low), "=d" (high) : "c" (msr_id));

  return ((grub_uint64_t)high << 32) | low;
}

#endif /* GRUB_RDMSR_H */