From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1C034C2D0CE for ; Fri, 24 Jan 2020 23:40:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EA468206D3 for ; Fri, 24 Jan 2020 23:40:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387404AbgAXXih (ORCPT ); Fri, 24 Jan 2020 18:38:37 -0500 Received: from mga11.intel.com ([192.55.52.93]:52242 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729147AbgAXXig (ORCPT ); Fri, 24 Jan 2020 18:38:36 -0500 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from orsmga006.jf.intel.com ([10.7.209.51]) by fmsmga102.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 24 Jan 2020 15:38:36 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.70,359,1574150400"; d="scan'208";a="230508456" Received: from sjchrist-coffee.jf.intel.com (HELO linux.intel.com) ([10.54.74.202]) by orsmga006.jf.intel.com with ESMTP; 24 Jan 2020 15:38:35 -0800 Date: Fri, 24 Jan 2020 15:38:35 -0800 From: Sean Christopherson To: Nadav Amit Cc: Aaron Lewis , kvm list , Jim Mattson , Paolo Bonzini , Liran Alon Subject: Re: [kvm-unit-tests PATCH v3] x86: Add RDTSC test Message-ID: <20200124233835.GT2109@linux.intel.com> References: <20191202204356.250357-1-aaronlewis@google.com> <4EFDEFF2-D1CD-4AF3-9EF8-5F160A4D93CD@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <4EFDEFF2-D1CD-4AF3-9EF8-5F160A4D93CD@gmail.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Fri, Jan 24, 2020 at 03:13:44PM -0800, Nadav Amit wrote: > > On Dec 2, 2019, at 12:43 PM, Aaron Lewis wrote: > > > > Verify that the difference between a guest RDTSC instruction and the > > IA32_TIME_STAMP_COUNTER MSR value stored in the VMCS12's VM-exit > > MSR-store list is less than 750 cycles, 99.9% of the time. > > > > 662f1d1d1931 ("KVM: nVMX: Add support for capturing highest observable L2 TSC”) > > > > Signed-off-by: Aaron Lewis > > Reviewed-by: Jim Mattson > > Running this test on bare-metal I get: > > Test suite: rdtsc_vmexit_diff_test > FAIL: RDTSC to VM-exit delta too high in 117 of 100000 iterations > > Any idea why? Should I just play with the 750 cycles magic number? Argh, this reminds me that I have a patch for this test to improve the error message to makes things easier to debug. Give me a few minutes to get it sent out, might help a bit.