Il 23/05/2013 14:25, Vadim Rozenfeld ha scritto: > > > ----- Original Message ----- > From: "Peter Lieven" <pl@xxxxxxxxx> > To: "Paolo Bonzini" <pbonzini@xxxxxxxxxx> > Cc: "Vadim Rozenfeld" <vrozenfe@xxxxxxxxxx>, "Marcelo Tosatti" <mtosatti@xxxxxxxxxx>, kvm@xxxxxxxxxxxxxxx, gleb@xxxxxxxxxx, pl@xxxxxxx > Sent: Thursday, May 23, 2013 4:17:57 PM > Subject: Re: [RFC PATCH v2 1/2] add support for Hyper-V reference time counter > > On 22.05.2013 23:55, Paolo Bonzini wrote: >> Il 22/05/2013 09:32, Vadim Rozenfeld ha scritto: >>>>> @@ -1827,6 +1829,29 @@ static int set_msr_hyperv_pw(struct kvm_vcpu *vcpu, u32 msr, u64 data) >>>>> if (__copy_to_user((void __user *)addr, instructions, 4)) >>>>> return 1; >>>>> kvm->arch.hv_hypercall = data; >>>>> + local_irq_disable(); >>>>> + kvm->arch.hv_ref_count = get_kernel_ns(); >>>>> + local_irq_enable(); >>>>> + break; >>> local_irq_disable/local_irq_enable not needed. >>> >>> >>> What is the reasoning behind reading this time value at msr write time? >>> [VR] Windows writs this MSR only once, during HAL initialization. >>> So, I decided to treat this call as a partition crate event. >>> >> >> But is it expected by Windows that the reference count starts counting >> up from 0 at partition creation time? If you could just use >> (get_kernel_ns() + kvm->arch.kvmclock_offset) / 100, it would also be >> simpler for migration purposes. > > I can just report, that I have used the patch that does it that way and it works. > Maybe Windows is calculating the uptime by the reference counter? > > [VR] > Windows use it (reference counters/iTSC/PMTimer/HPET) as a time-stamp source > for (Ke)QueryPerformanceCounter function. So I would prefer to remove kvm->arch.hv_ref_count altogether. Paolo -- 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
