From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paolo Bonzini Subject: Re: [PATCH v1] kvm/x86: Hyper-V tsc page setup Date: Wed, 20 Jan 2016 22:10:06 +0100 Message-ID: <569FF7AE.7060207@redhat.com> References: <1450949580-25759-1-git-send-email-asmetanin@virtuozzo.com> <569DEA3B.2040107@openvz.org> <569F9419.4000601@redhat.com> <569F9D61.5020203@openvz.org> <20160120145218.GH26969@rkaganb.sw.ru> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit To: Roman Kagan , "Denis V. Lunev" , Andrey Smetanin , kvm@vger.kernel.org, Gleb Natapov , qemu-devel@nongnu.org Return-path: Received: from mail-wm0-f65.google.com ([74.125.82.65]:35765 "EHLO mail-wm0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750781AbcATVKJ (ORCPT ); Wed, 20 Jan 2016 16:10:09 -0500 Received: by mail-wm0-f65.google.com with SMTP id 123so6705684wmz.2 for ; Wed, 20 Jan 2016 13:10:09 -0800 (PST) In-Reply-To: <20160120145218.GH26969@rkaganb.sw.ru> Sender: kvm-owner@vger.kernel.org List-ID: On 20/01/2016 15:52, Roman Kagan wrote: > I think Paolo wanted to be compatible not only with the de facto > implementation in Windows Hyper-V guests, but also with the Linux driver > which followed the buggy spec and thought 0xFFFFFFFF to be invalid. 0xFFFFFFFF is not invalid; it means it is valid but you have to use the MSR. With 0, you cannot use the MSR either and Windows will use the ACPI PM timer or similar. You can see the difference from the result of QueryPerformanceFrequency, IIRC. Paolo