From mboxrd@z Thu Jan 1 00:00:00 1970 From: Konrad Rzeszutek Wilk Subject: Re: [PATCH v2 0/4] i386/kvm: advertise Hyper-V frequency MSRs Date: Tue, 15 Aug 2017 21:49:38 -0400 Message-ID: <20170816014938.GC12928@localhost.localdomain> References: <20170807085703.32267-1-lprosek@redhat.com> <20170809005053.GA26386@amt.cnet> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Ladi Prosek , qemu-devel@nongnu.org, kvm@vger.kernel.org, pbonzini@redhat.com, david@redhat.com, rkrcmar@redhat.com To: Marcelo Tosatti Return-path: Received: from userp1040.oracle.com ([156.151.31.81]:51889 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753297AbdHPBuD (ORCPT ); Tue, 15 Aug 2017 21:50:03 -0400 Content-Disposition: inline In-Reply-To: <20170809005053.GA26386@amt.cnet> Sender: kvm-owner@vger.kernel.org List-ID: On Tue, Aug 08, 2017 at 09:50:53PM -0300, Marcelo Tosatti wrote: > On Mon, Aug 07, 2017 at 10:56:59AM +0200, Ladi Prosek wrote: > > This is the QEMU part of the changes required for nested Hyper-V to read > > timestamps with RDTSC + TSC page. Without exposing the frequency MSRs, > > Windows with the Hyper-V role enabled use the much slower > > HV_X64_MSR_TIME_REF_COUNT (0x40000020) RDMSR to read timestamps. > > > > The new registers are exposed only if the TSC frequency is stable across > > migration and known, as suggested by Paolo. > > > > v1->v2: > > * deleted an extra empty line in patch 1 > > * added patch 3 introducing a helper function for the "TSC is stable and > > known" check (David) > > > > Ladi Prosek (4): > > i386/kvm: use a switch statement for MSR detection > > i386/kvm: set tsc_khz before configuring Hyper-V CPUID > > i386/kvm: introduce tsc_is_stable_and_known() > > i386/kvm: advertise Hyper-V frequency MSRs > > > > target/i386/kvm.c | 138 ++++++++++++++++++++++++++++-------------------------- > > 1 file changed, 71 insertions(+), 67 deletions(-) > > > > -- > > 2.9.3 > > > Signed-off-by: Marcelo Tosatti Come again please? >