include/asm-x86/pvclock-abi.h

   1 #ifndef _ASM_X86_PVCLOCK_ABI_H_
   2 #define _ASM_X86_PVCLOCK_ABI_H_
   3 #ifndef __ASSEMBLY__
   4
   5 /*
   6  * These structs MUST NOT be changed.
   7  * They are the ABI between hypervisor and guest OS.
   8  * Both Xen and KVM are using this.
   9  *
  10  * pvclock_vcpu_time_info holds the system time and the tsc timestamp
  11  * of the last update. So the guest can use the tsc delta to get a
  12  * more precise system time.  There is one per virtual cpu.
  13  *
  14  * pvclock_wall_clock references the point in time when the system
  15  * time was zero (usually boot time), thus the guest calculates the
  16  * current wall clock by adding the system time.
  17  *
  18  * Protocol for the "version" fields is: hypervisor raises it (making
  19  * it uneven) before it starts updating the fields and raises it again
  20  * (making it even) when it is done.  Thus the guest can make sure the
  21  * time values it got are consistent by checking the version before
  22  * and after reading them.
  23  */
  24
  25 struct pvclock_vcpu_time_info {
  26         u32   version;
  27         u32   pad0;
  28         u64   tsc_timestamp;
  29         u64   system_time;
  30         u32   tsc_to_system_mul;
  31         s8    tsc_shift;
  32         u8    pad[3];
  33 } __attribute__((__packed__)); /* 32 bytes */
  34
  35 struct pvclock_wall_clock {
  36         u32   version;
  37         u32   sec;
  38         u32   nsec;
  39 } __attribute__((__packed__));
  40
  41 #endif /* __ASSEMBLY__ */
  42 #endif /* _ASM_X86_PVCLOCK_ABI_H_ */