From 7af192c954017499ec163bc9dbaaee2e593d7ef2 Mon Sep 17 00:00:00 2001 From: Gerd Hoffmann Date: Tue, 3 Jun 2008 16:17:29 +0200 Subject: x86: Add structs and functions for paravirt clocksource This patch adds structs for the paravirt clocksource ABI used by both xen and kvm (pvclock-abi.h). It also adds some helper functions to read system time and wall clock time from a paravirtual clocksource (pvclock.[ch]). They are based on the xen code. They are enabled using CONFIG_PARAVIRT_CLOCK. Subsequent patches of this series will put the code in use. Signed-off-by: Gerd Hoffmann Acked-by: Jeremy Fitzhardinge Signed-off-by: Avi Kivity --- include/asm-x86/pvclock-abi.h | 42 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 42 insertions(+) create mode 100644 include/asm-x86/pvclock-abi.h (limited to 'include/asm-x86/pvclock-abi.h') diff --git a/include/asm-x86/pvclock-abi.h b/include/asm-x86/pvclock-abi.h new file mode 100644 index 000000000000..6857f840b243 --- /dev/null +++ b/include/asm-x86/pvclock-abi.h @@ -0,0 +1,42 @@ +#ifndef _ASM_X86_PVCLOCK_ABI_H_ +#define _ASM_X86_PVCLOCK_ABI_H_ +#ifndef __ASSEMBLY__ + +/* + * These structs MUST NOT be changed. + * They are the ABI between hypervisor and guest OS. + * Both Xen and KVM are using this. + * + * pvclock_vcpu_time_info holds the system time and the tsc timestamp + * of the last update. So the guest can use the tsc delta to get a + * more precise system time. There is one per virtual cpu. + * + * pvclock_wall_clock references the point in time when the system + * time was zero (usually boot time), thus the guest calculates the + * current wall clock by adding the system time. + * + * Protocol for the "version" fields is: hypervisor raises it (making + * it uneven) before it starts updating the fields and raises it again + * (making it even) when it is done. Thus the guest can make sure the + * time values it got are consistent by checking the version before + * and after reading them. + */ + +struct pvclock_vcpu_time_info { + u32 version; + u32 pad0; + u64 tsc_timestamp; + u64 system_time; + u32 tsc_to_system_mul; + s8 tsc_shift; + u8 pad[3]; +} __attribute__((__packed__)); /* 32 bytes */ + +struct pvclock_wall_clock { + u32 version; + u32 sec; + u32 nsec; +} __attribute__((__packed__)); + +#endif /* __ASSEMBLY__ */ +#endif /* _ASM_X86_PVCLOCK_ABI_H_ */ -- cgit v1.2.3