On Tue, Aug 27, 2013 at 11:55:29PM -0300, Marcelo Tosatti wrote:
>
> 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 <mtosatti@xxxxxxxxxx>
>
Applied, thanks.
> 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];
>
--
Gleb.
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