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authorGerd Hoffmann <kraxel@redhat.com>2008-06-03 16:17:29 +0200
committerAvi Kivity <avi@qumranet.com>2008-06-24 21:02:31 +0300
commit7af192c954017499ec163bc9dbaaee2e593d7ef2 (patch)
tree04e28552d1e1e265443933e3e658949170997c0e /include
parenta9b21b622958afc3f3bc5a23d266dd9ed1171fd3 (diff)
downloadlinux-7af192c954017499ec163bc9dbaaee2e593d7ef2.tar.bz2
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 <kraxel@redhat.com> Acked-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Signed-off-by: Avi Kivity <avi@qumranet.com>
Diffstat (limited to 'include')
-rw-r--r--include/asm-x86/pvclock-abi.h42
-rw-r--r--include/asm-x86/pvclock.h13
2 files changed, 55 insertions, 0 deletions
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_ */
diff --git a/include/asm-x86/pvclock.h b/include/asm-x86/pvclock.h
new file mode 100644
index 000000000000..85b1bba8e0a3
--- /dev/null
+++ b/include/asm-x86/pvclock.h
@@ -0,0 +1,13 @@
+#ifndef _ASM_X86_PVCLOCK_H_
+#define _ASM_X86_PVCLOCK_H_
+
+#include <linux/clocksource.h>
+#include <asm/pvclock-abi.h>
+
+/* some helper functions for xen and kvm pv clock sources */
+cycle_t pvclock_clocksource_read(struct pvclock_vcpu_time_info *src);
+void pvclock_read_wallclock(struct pvclock_wall_clock *wall,
+ struct pvclock_vcpu_time_info *vcpu,
+ struct timespec *ts);
+
+#endif /* _ASM_X86_PVCLOCK_H_ */