diff options
Diffstat (limited to 'arch/x86/kernel/kvmclock.c')
| -rw-r--r-- | arch/x86/kernel/kvmclock.c | 46 |
1 files changed, 35 insertions, 11 deletions
diff --git a/arch/x86/kernel/kvmclock.c b/arch/x86/kernel/kvmclock.c index 2c7aafa70..2bd81e302 100644 --- a/arch/x86/kernel/kvmclock.c +++ b/arch/x86/kernel/kvmclock.c @@ -32,6 +32,7 @@ static int kvmclock = 1; static int msr_kvm_system_time = MSR_KVM_SYSTEM_TIME; static int msr_kvm_wall_clock = MSR_KVM_WALL_CLOCK; +static cycle_t kvm_sched_clock_offset; static int parse_no_kvmclock(char *arg) { @@ -92,6 +93,29 @@ static cycle_t kvm_clock_get_cycles(struct clocksource *cs) return kvm_clock_read(); } +static cycle_t kvm_sched_clock_read(void) +{ + return kvm_clock_read() - kvm_sched_clock_offset; +} + +static inline void kvm_sched_clock_init(bool stable) +{ + if (!stable) { + pv_time_ops.sched_clock = kvm_clock_read; + return; + } + + kvm_sched_clock_offset = kvm_clock_read(); + pv_time_ops.sched_clock = kvm_sched_clock_read; + set_sched_clock_stable(); + + printk(KERN_INFO "kvm-clock: using sched offset of %llu cycles\n", + kvm_sched_clock_offset); + + BUILD_BUG_ON(sizeof(kvm_sched_clock_offset) > + sizeof(((struct pvclock_vcpu_time_info *)NULL)->system_time)); +} + /* * If we don't do that, there is the possibility that the guest * will calibrate under heavy load - thus, getting a lower lpj - @@ -248,7 +272,17 @@ void __init kvmclock_init(void) memblock_free(mem, size); return; } - pv_time_ops.sched_clock = kvm_clock_read; + + if (kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE_STABLE_BIT)) + pvclock_set_flags(PVCLOCK_TSC_STABLE_BIT); + + cpu = get_cpu(); + vcpu_time = &hv_clock[cpu].pvti; + flags = pvclock_read_flags(vcpu_time); + + kvm_sched_clock_init(flags & PVCLOCK_TSC_STABLE_BIT); + put_cpu(); + x86_platform.calibrate_tsc = kvm_get_tsc_khz; x86_platform.get_wallclock = kvm_get_wallclock; x86_platform.set_wallclock = kvm_set_wallclock; @@ -265,16 +299,6 @@ void __init kvmclock_init(void) kvm_get_preset_lpj(); clocksource_register_hz(&kvm_clock, NSEC_PER_SEC); pv_info.name = "KVM"; - - if (kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE_STABLE_BIT)) - pvclock_set_flags(~0); - - cpu = get_cpu(); - vcpu_time = &hv_clock[cpu].pvti; - flags = pvclock_read_flags(vcpu_time); - if (flags & PVCLOCK_COUNTS_FROM_ZERO) - set_sched_clock_stable(); - put_cpu(); } int __init kvm_setup_vsyscall_timeinfo(void) |