From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wanpeng Li Subject: Re: Seeking a KVM benchmark Date: Mon, 17 Nov 2014 20:00:33 +0800 Message-ID: <5469E361.60308@gmail.com> References: <545C7222.4070605@redhat.com> <20141108120125.GB2654@minantech.com> <20141109085238.GA26187@minantech.com> <54608D77.2090907@redhat.com> <20141110104531.GB26187@minantech.com> <5460AC7C.8040409@redhat.com> <5460CA71.2050701@gmail.com> <5460F5B9.8030902@redhat.com> <5469D934.4080405@gmail.com> <5469D974.4030008@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Cc: Andy Lutomirski , kvm list To: Paolo Bonzini , Avi Kivity , Gleb Natapov Return-path: Received: from mail-pa0-f49.google.com ([209.85.220.49]:48749 "EHLO mail-pa0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750740AbaKQMBC (ORCPT ); Mon, 17 Nov 2014 07:01:02 -0500 Received: by mail-pa0-f49.google.com with SMTP id eu11so366643pac.8 for ; Mon, 17 Nov 2014 04:01:01 -0800 (PST) In-Reply-To: <5469D974.4030008@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: Hi Paolo, On 11/17/14, 7:18 PM, Paolo Bonzini wrote: > > On 17/11/2014 12:17, Wanpeng Li wrote: >>>> It's not surprising [1]. Since the meaning of some PTE bits change [2], >>>> the TLB has to be flushed. In VMX we have VPIDs, so we only need to flush >>>> if EFER changed between two invocations of the same VPID, which isn't >>>> the case. >> If there need a TLB flush if guest is UP? > The wrmsr is in the host, and the TLB flush is done in the processor > microcode. Sorry, maybe I didn't state my question clearly. As Avi mentioned above "In VMX we have VPIDs, so we only need to flush if EFER changed between two invocations of the same VPID", so there is only one VPID if the guest is UP, my question is if there need a TLB flush when guest's EFER has been changed? Regards, Wanpeng Li > > Paolo