1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef _ASM_X86_PVCLOCK_ABI_H
3#define _ASM_X86_PVCLOCK_ABI_H
4#ifndef __ASSEMBLER__
5
6/*
7 * These structs MUST NOT be changed.
8 * They are the ABI between hypervisor and guest OS.
9 * Both Xen and KVM are using this.
10 *
11 * pvclock_vcpu_time_info holds the system time and the tsc timestamp
12 * of the last update. So the guest can use the tsc delta to get a
13 * more precise system time. There is one per virtual cpu.
14 *
15 * pvclock_wall_clock references the point in time when the system
16 * time was zero (usually boot time), thus the guest calculates the
17 * current wall clock by adding the system time.
18 *
19 * Protocol for the "version" fields is: hypervisor raises it (making
20 * it uneven) before it starts updating the fields and raises it again
21 * (making it even) when it is done. Thus the guest can make sure the
22 * time values it got are consistent by checking the version before
23 * and after reading them.
24 */
25
26struct pvclock_vcpu_time_info {
27 u32 version;
28 u32 pad0;
29 u64 tsc_timestamp;
30 u64 system_time;
31 u32 tsc_to_system_mul;
32 s8 tsc_shift;
33 u8 flags;
34 u8 pad[2];
35} __attribute__((__packed__)); /* 32 bytes */
36
37struct pvclock_wall_clock {
38 u32 version;
39 u32 sec;
40 u32 nsec;
41} __attribute__((__packed__));
42
43#define PVCLOCK_TSC_STABLE_BIT (1 << 0)
44#define PVCLOCK_GUEST_STOPPED (1 << 1)
45/* PVCLOCK_COUNTS_FROM_ZERO broke ABI and can't be used anymore. */
46#define PVCLOCK_COUNTS_FROM_ZERO (1 << 2)
47#endif /* __ASSEMBLER__ */
48#endif /* _ASM_X86_PVCLOCK_ABI_H */
49

source code of linux/arch/x86/include/asm/pvclock-abi.h