On Thu, May 09, 2013 at 08:21:41PM -0300, Marcelo Tosatti wrote: > > kvmclock updates which are isolated to a given vcpu, such as vcpu->cpu > migration, should not allow system_timestamp from the rest of the vcpus > to remain static. Otherwise ntp frequency correction applies to one > vcpu's system_timestamp but not the others. > > So in those cases, request a kvmclock update for all vcpus. The worst > case for a remote vcpu to update its kvmclock is then bounded by maximum > nohz sleep latency. > Does this mean that when one vcpu is migrated all others are kicked out from a guest mode?
> Signed-off-by: Marcelo Tosatti <[email protected]> > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 94f35d2..a37cadc 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -1569,6 +1569,30 @@ static int kvm_guest_time_update(struct kvm_vcpu *v) > return 0; > } > > +/* > + * kvmclock updates which are isolated to a given vcpu, such as > + * vcpu->cpu migration, should not allow system_timestamp from > + * the rest of the vcpus to remain static. Otherwise ntp frequency > + * correction applies to one vcpu's system_timestamp but not > + * the others. > + * > + * So in those cases, request a kvmclock update for all vcpus. > + * The worst case for a remote vcpu to update its kvmclock > + * is then bounded by maximum nohz sleep latency. > + */ > + > +static void kvm_gen_kvmclock_update(struct kvm_vcpu *v) > +{ > + int i; > + struct kvm *kvm = v->kvm; > + struct kvm_vcpu *vcpu; > + > + kvm_for_each_vcpu(i, vcpu, kvm) { > + set_bit(KVM_REQ_CLOCK_UPDATE, &vcpu->requests); > + kvm_vcpu_kick(vcpu); > + } > +} > + > static bool msr_mtrr_valid(unsigned msr) > { > switch (msr) { > @@ -1965,7 +1989,7 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct > msr_data *msr_info) > kvmclock_reset(vcpu); > > vcpu->arch.time = data; > - kvm_make_request(KVM_REQ_CLOCK_UPDATE, vcpu); > + kvm_make_request(KVM_REQ_GLOBAL_CLOCK_UPDATE, vcpu); > > /* we verify if the enable bit is set... */ > if (!(data & 1)) > @@ -2684,7 +2708,7 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu) > * kvmclock on vcpu->cpu migration > */ > if (!vcpu->kvm->arch.use_master_clock || vcpu->cpu == -1) > - kvm_make_request(KVM_REQ_CLOCK_UPDATE, vcpu); > + kvm_make_request(KVM_REQ_GLOBAL_CLOCK_UPDATE, vcpu); > if (vcpu->cpu != cpu) > kvm_migrate_timers(vcpu); > vcpu->cpu = cpu; > @@ -5704,6 +5728,8 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) > __kvm_migrate_timers(vcpu); > if (kvm_check_request(KVM_REQ_MASTERCLOCK_UPDATE, vcpu)) > kvm_gen_update_masterclock(vcpu->kvm); > + if (kvm_check_request(KVM_REQ_GLOBAL_CLOCK_UPDATE, vcpu)) > + kvm_gen_kvmclock_update(vcpu); > if (kvm_check_request(KVM_REQ_CLOCK_UPDATE, vcpu)) { > r = kvm_guest_time_update(vcpu); > if (unlikely(r)) > diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h > index 7823b63..044b0b9 100644 > --- a/include/linux/kvm_host.h > +++ b/include/linux/kvm_host.h > @@ -126,6 +126,7 @@ static inline bool is_error_page(struct page *page) > #define KVM_REQ_MCLOCK_INPROGRESS 19 > #define KVM_REQ_EPR_EXIT 20 > #define KVM_REQ_SCAN_IOAPIC 21 > +#define KVM_REQ_GLOBAL_CLOCK_UPDATE 22 > > #define KVM_USERSPACE_IRQ_SOURCE_ID 0 > #define KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID 1 > -- > To unsubscribe from this list: send the line "unsubscribe kvm" in > the body of a message to [email protected] > More majordomo info at http://vger.kernel.org/majordomo-info.html -- Gleb. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
