On Wed, Jun 16, 2010 at 04:12:46PM +0800, Jason Wang wrote: > Zachary Amsden wrote: > > On 06/14/2010 10:41 PM, Avi Kivity wrote: > > > >> On 06/15/2010 10:34 AM, Zachary Amsden wrote: > >> > >>> Add a helper function for the multiple places this is used. Note > >>> that it > >>> must not be called in preemptible context, as that would mean the kernel > >>> could enter software suspend state, which would cause non-atomic > >>> operation > >>> of the monotonic_to_bootbased computation. > >>> > >>> Open question: should the KVM_SET_CLOCK / KVM_GET_CLOCK ioctls use this > >>> as well? Currently, they are not bootbased (but perhaps should be). > >>> > >>> Signed-off-by: Zachary Amsden<zamsden@xxxxxxxxxx> > >>> --- > >>> arch/x86/kvm/x86.c | 26 +++++++++++++------------- > >>> 1 files changed, 13 insertions(+), 13 deletions(-) > >>> > >>> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > >>> index 703ea43..15c7317 100644 > >>> --- a/arch/x86/kvm/x86.c > >>> +++ b/arch/x86/kvm/x86.c > >>> @@ -915,6 +915,16 @@ static void kvm_get_time_scale(uint32_t > >>> scaled_khz, uint32_t base_khz, > >>> __func__, base_khz, scaled_khz, shift, *pmultiplier); > >>> } > >>> > >>> +static inline u64 get_kernel_ns(void) > >>> +{ > >>> + struct timespec ts; > >>> + > >>> + WARN_ON(preemptible()); > >>> + ktime_get_ts(&ts); > >>> + monotonic_to_bootbased(&ts); > >>> + return timespec_to_ns(&ts); > >>> +} > >>> + > >>> static DEFINE_PER_CPU(unsigned long, cpu_tsc_khz); > >>> > >>> > >> Isn't something like this a candidate for the time infrastructure? > >> > >> > > > > Should it be? It certainly seems reasonable. > > > > > > Also, should we be using it for the cases KVM_GET_CLOCK / > > KVM_SET_CLOCK? It seems global kvmclock_offset for the VM ignores the > > bootbased conversion. > > > > > Yes we should. indeed. Also shows the importance of doing it in a central place. Have we had an acessor like that before, we would probably not have made this mistake. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html