The offset to add to the hosts monotonic time, kvmclock_offset, is calculated against the monotonic time at KVM_SET_CLOCK ioctl time.
Request a master clock update at this time, to reduce a potentially unbounded difference between the values of the masterclock and the clock value used to calculate kvmclock_offset. Signed-off-by: Marcelo Tosatti <[email protected]> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index d21bce5..0a93354 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -1457,6 +1457,29 @@ static void pvclock_update_vm_gtod_copy(struct kvm *kvm) #endif } +static void kvm_gen_update_masterclock(struct kvm *kvm) +{ +#ifdef CONFIG_X86_64 + int i; + struct kvm_vcpu *vcpu; + struct kvm_arch *ka = &kvm->arch; + + spin_lock(&ka->pvclock_gtod_sync_lock); + kvm_make_mclock_inprogress_request(kvm); + /* no guest entries from this point */ + pvclock_update_vm_gtod_copy(kvm); + + kvm_for_each_vcpu(i, vcpu, kvm) + set_bit(KVM_REQ_CLOCK_UPDATE, &vcpu->requests); + + /* guest entries allowed */ + kvm_for_each_vcpu(i, vcpu, kvm) + clear_bit(KVM_REQ_MCLOCK_INPROGRESS, &vcpu->requests); + + spin_unlock(&ka->pvclock_gtod_sync_lock); +#endif +} + static int kvm_guest_time_update(struct kvm_vcpu *v) { unsigned long flags, this_tsc_khz; @@ -3806,6 +3829,7 @@ long kvm_arch_vm_ioctl(struct file *filp, delta = user_ns.clock - now_ns; local_irq_enable(); kvm->arch.kvmclock_offset = delta; + kvm_gen_update_masterclock(kvm); break; } case KVM_GET_CLOCK: { @@ -5689,29 +5713,6 @@ static void process_nmi(struct kvm_vcpu *vcpu) kvm_make_request(KVM_REQ_EVENT, vcpu); } -static void kvm_gen_update_masterclock(struct kvm *kvm) -{ -#ifdef CONFIG_X86_64 - int i; - struct kvm_vcpu *vcpu; - struct kvm_arch *ka = &kvm->arch; - - spin_lock(&ka->pvclock_gtod_sync_lock); - kvm_make_mclock_inprogress_request(kvm); - /* no guest entries from this point */ - pvclock_update_vm_gtod_copy(kvm); - - kvm_for_each_vcpu(i, vcpu, kvm) - set_bit(KVM_REQ_CLOCK_UPDATE, &vcpu->requests); - - /* guest entries allowed */ - kvm_for_each_vcpu(i, vcpu, kvm) - clear_bit(KVM_REQ_MCLOCK_INPROGRESS, &vcpu->requests); - - spin_unlock(&ka->pvclock_gtod_sync_lock); -#endif -} - static void vcpu_scan_ioapic(struct kvm_vcpu *vcpu) { u64 eoi_exit_bitmap[4]; -- 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
