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: Wed, 22 May 2013 23:55:34 +0200 Message-ID: <519D3ED6.8010804@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> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Cc: Marcelo Tosatti , kvm@vger.kernel.org, gleb@redhat.com, pl@dlh.net To: Vadim Rozenfeld Return-path: Received: from mail-ee0-f52.google.com ([74.125.83.52]:49338 "EHLO mail-ee0-f52.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756475Ab3EVVzo (ORCPT ); Wed, 22 May 2013 17:55:44 -0400 Received: by mail-ee0-f52.google.com with SMTP id c13so1398259eek.11 for ; Wed, 22 May 2013 14:55:43 -0700 (PDT) In-Reply-To: <745195650.5763962.1369207977883.JavaMail.root@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: 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. Paolo