From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vadim Rozenfeld Subject: Re: [RFC PATCH v3 2/2] add support for Hyper-V partition reference time enlightenment Date: Tue, 10 Dec 2013 22:23:17 +1100 Message-ID: <1386674597.32091.55.camel@localhost> References: <1386502419-26614-1-git-send-email-vrozenfe@redhat.com> <1386502419-26614-3-git-send-email-vrozenfe@redhat.com> <52A5D497.1070308@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: kvm@vger.kernel.org, mtosatti@redhat.com, pl@dlhnet.de To: Paolo Bonzini Return-path: Received: from mx1.redhat.com ([209.132.183.28]:49693 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751313Ab3LJLX1 (ORCPT ); Tue, 10 Dec 2013 06:23:27 -0500 In-Reply-To: <52A5D497.1070308@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On Mon, 2013-12-09 at 15:32 +0100, Paolo Bonzini wrote: > Il 08/12/2013 12:33, Vadim Rozenfeld ha scritto: > > + tsc_ref.tsc_sequence = > > + boot_cpu_has(X86_FEATURE_CONSTANT_TSC) ? 1 : 0; > > + tsc_ref.tsc_scale = > > + ((10000LL << 32) / vcpu->arch.virtual_tsc_khz) << 32; > > + tsc_ref.tsc_offset = 0; > > if (__copy_to_user((void __user *)addr, &tsc_ref, sizeof(tsc_ref))) > > return 1; > > mark_page_dirty(kvm, gfn); > > kvm->arch.hv_tsc_page = data; > > + kvm->arch.hv_ref_count = 0; > > break; > > } > > default: > > @@ -3879,6 +3884,19 @@ long kvm_arch_vm_ioctl(struct file *filp, > > local_irq_enable(); > > kvm->arch.kvmclock_offset = delta; > > kvm_gen_update_masterclock(kvm); > > + > > + if (kvm->arch.hv_tsc_page & HV_X64_MSR_TSC_REFERENCE_ENABLE) { > > + HV_REFERENCE_TSC_PAGE* tsc_ref; > > + u64 curr_time; > > + tsc_ref = (HV_REFERENCE_TSC_PAGE*)gfn_to_hva(kvm, > > + kvm->arch.hv_tsc_page >> HV_X64_MSR_TSC_REFERENCE_ADDRESS_SHIFT); > > + tsc_ref->tsc_sequence = > > + boot_cpu_has(X86_FEATURE_CONSTANT_TSC) ? tsc_ref->tsc_sequence + 1 : 0; > > + tsc_ref->tsc_scale = ((10000LL << 32) / __get_cpu_var(cpu_tsc_khz)) << 32; > > Why shouldn't this be vcpu->arch.virtual_tsc_khz? Yeah, I was thinking about that, but we need a vcpu instance for this. > > > + curr_time = (((tsc_ref->tsc_scale >> 32) * native_read_tsc()) >> 32) + > > + tsc_ref->tsc_offset; > > + tsc_ref->tsc_offset = kvm->arch.hv_ref_time - curr_time; > > + } > > The difference in setting tsc_ref->tsc_scale is the only important > change between the two occurrences. If you can avoid that difference > and you move this to a separate function, you can reuse that new > function in set_msr_hyperv_pw as well. Do you mean between HV_X64_MSR_REFERENCE_TSC which happens during partition creation time and KVM_SET_CLOCK which happens during resume after partition pause? If so - there are several differences, where the offset calculation probably is the most important one. Vadim. > > Also, kvm_set_tsc_khz should recompute the reference page's values as > well, so you'd have three uses. > > Paolo