aboutsummaryrefslogtreecommitdiffstats
path: root/include/asm-x86/pvclock-abi.h
diff options
context:
space:
mode:
Diffstat (limited to 'include/asm-x86/pvclock-abi.h')
-rw-r--r--include/asm-x86/pvclock-abi.h42
1 files changed, 42 insertions, 0 deletions
diff --git a/include/asm-x86/pvclock-abi.h b/include/asm-x86/pvclock-abi.h
new file mode 100644
index 00000000000..6857f840b24
--- /dev/null
+++ b/include/asm-x86/pvclock-abi.h
@@ -0,0 +1,42 @@
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
25struct 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
35struct 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_ */