commit 0061d53daf26f introduced a mechanism to execute a global clock update for a vm. We can apply this periodically in order to propagate host NTP corrections. Also, if all vcpus of a vm are pinned, then without an additional trigger, no guest NTP corrections can propagate either, as the current trigger is only vcpu cpu migration.
Signed-off-by: Andrew Jones <[email protected]> --- arch/x86/include/asm/kvm_host.h | 1 + arch/x86/kvm/x86.c | 65 +++++++++++++++++++++++++++++++++++++++-- 2 files changed, 63 insertions(+), 3 deletions(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 9aa09d330a4b5..77c69aa4756f9 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -599,6 +599,7 @@ struct kvm_arch { u64 master_kernel_ns; cycle_t master_cycle_now; struct delayed_work kvmclock_update_work; + bool clocks_synced; struct kvm_xen_hvm_config xen_hvm_config; diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index a2d30de597b7d..5cba20b446aac 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -1620,6 +1620,60 @@ static int kvm_guest_time_update(struct kvm_vcpu *v) return 0; } +static void kvm_schedule_kvmclock_update(struct kvm *kvm, bool now); +static void clock_sync_fn(struct work_struct *work); +static DECLARE_DELAYED_WORK(clock_sync_work, clock_sync_fn); + +#define CLOCK_SYNC_PERIOD_SECS 300 +#define CLOCK_SYNC_BUMP_SECS 30 +#define CLOCK_SYNC_STEP_MSECS 100 + +#define __steps(s) (((s) * MSEC_PER_SEC) / CLOCK_SYNC_STEP_MSECS) + +static void clock_sync_fn(struct work_struct *work) +{ + static unsigned reset_step = __steps(CLOCK_SYNC_PERIOD_SECS); + static unsigned step = 0; + struct kvm *kvm; + bool sync = false; + + spin_lock(&kvm_lock); + + if (step == 0) + list_for_each_entry(kvm, &vm_list, vm_list) + kvm->arch.clocks_synced = false; + + list_for_each_entry(kvm, &vm_list, vm_list) { + if (!kvm->arch.clocks_synced) { + kvm_get_kvm(kvm); + sync = true; + break; + } + } + + spin_unlock(&kvm_lock); + + if (sync) { + kvm_schedule_kvmclock_update(kvm, true); + kvm_put_kvm(kvm); + + if (++step == reset_step) { + reset_step += __steps(CLOCK_SYNC_BUMP_SECS); + pr_warn("kvmclock: reducing VM clock sync frequency " + "to every %ld seconds.\n", (reset_step + * CLOCK_SYNC_STEP_MSECS)/MSEC_PER_SEC); + } + + schedule_delayed_work(&clock_sync_work, + msecs_to_jiffies(CLOCK_SYNC_STEP_MSECS)); + } else { + unsigned s = reset_step - step; + step = 0; + schedule_delayed_work(&clock_sync_work, + msecs_to_jiffies(s * CLOCK_SYNC_STEP_MSECS)); + } +} + /* * kvmclock updates which are isolated to a given vcpu, such as * vcpu->cpu migration, should not allow system_timestamp from @@ -1652,11 +1706,12 @@ static void kvmclock_update_fn(struct work_struct *work) kvm_put_kvm(kvm); } -static void kvm_schedule_kvmclock_update(struct kvm *kvm) +static void kvm_schedule_kvmclock_update(struct kvm *kvm, bool now) { kvm_get_kvm(kvm); + kvm->arch.clocks_synced = true; schedule_delayed_work(&kvm->arch.kvmclock_update_work, - KVMCLOCK_UPDATE_DELAY); + now ? 0 : KVMCLOCK_UPDATE_DELAY); } static void kvm_gen_kvmclock_update(struct kvm_vcpu *v) @@ -1664,7 +1719,7 @@ static void kvm_gen_kvmclock_update(struct kvm_vcpu *v) struct kvm *kvm = v->kvm; set_bit(KVM_REQ_CLOCK_UPDATE, &v->requests); - kvm_schedule_kvmclock_update(kvm); + kvm_schedule_kvmclock_update(kvm, false); } static bool msr_mtrr_valid(unsigned msr) @@ -5584,6 +5639,8 @@ int kvm_arch_init(void *opaque) pvclock_gtod_register_notifier(&pvclock_gtod_notifier); #endif + schedule_delayed_work(&clock_sync_work, CLOCK_SYNC_PERIOD_SECS * HZ); + return 0; out_free_percpu: @@ -5594,6 +5651,8 @@ out: void kvm_arch_exit(void) { + cancel_delayed_work_sync(&clock_sync_work); + perf_unregister_guest_info_callbacks(&kvm_guest_cbs); if (!boot_cpu_has(X86_FEATURE_CONSTANT_TSC)) -- 1.8.1.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
