From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paolo Bonzini Subject: Re: [RFC PATCH v2 1/2] add support for Hyper-V reference time counter Date: Thu, 23 May 2013 11:54:15 +0200 Message-ID: <519DE747.9070303@redhat.com> References: <1368947197-9033-1-git-send-email-vrozenfe@redhat.com> <1368947197-9033-2-git-send-email-vrozenfe@redhat.com> <20130522004614.GA7322@amt.cnet> <745195650.5763962.1369207977883.JavaMail.root@redhat.com> <519D3ED6.8010804@redhat.com> <519DB495.8040708@dlhnet.de> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Cc: Vadim Rozenfeld , Marcelo Tosatti , kvm@vger.kernel.org, gleb@redhat.com, pl@dlh.net To: Peter Lieven Return-path: Received: from mx1.redhat.com ([209.132.183.28]:64191 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757494Ab3EWJy1 (ORCPT ); Thu, 23 May 2013 05:54:27 -0400 In-Reply-To: <519DB495.8040708@dlhnet.de> Sender: kvm-owner@vger.kernel.org List-ID: Il 23/05/2013 08:17, Peter Lieven ha scritto: > 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. What do you mean by "that way"? :) Paolo > Maybe Windows is calculating the uptime by the reference counter? > > Peter >