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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 355DFC433FE for ; Tue, 12 Apr 2022 21:22:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229876AbiDLVYj (ORCPT ); Tue, 12 Apr 2022 17:24:39 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57826 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229455AbiDLVYf (ORCPT ); Tue, 12 Apr 2022 17:24:35 -0400 Received: from mga11.intel.com (mga11.intel.com [192.55.52.93]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 23D0218114F; Tue, 12 Apr 2022 14:05:37 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1649797537; x=1681333537; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=BHLbe/RoUopliJXw7PZpTsR/hL9ogzQTYddN+kx+atU=; b=KSDBD8iYzCqN0x5BreM7rl7BmaJucB/khEuSIT0O2+sKfLIOtNURroMp bQHgDtDdXl42OAMFtkpdMGbpEbl03hzlKod9hWZ8ltuPBRgaVkjtVrzd3 morhyAleYJ+A3lNyxYaY7ia0rHEgrK0aRxQClhLaW2LUQY4TQUOtCOZ3/ XldR5ldXOKdBMiE6AJWBsJ8gEY+tjt0wyZurIRCD3/fZ6mGF72zT3euSz T+KozsHjkg1i9y5uDnqLcFQobc7xog19ZtoWSK/cR4yRZD7/2PzaLixPH 9ZhzaSV6JLrRRW52HQwhdJCUp5e9hnS9fjiRtZ/J1kqZePT/5UURnFAoP w==; X-IronPort-AV: E=McAfee;i="6400,9594,10315"; a="260098619" X-IronPort-AV: E=Sophos;i="5.90,254,1643702400"; d="scan'208";a="260098619" Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by fmsmga102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 Apr 2022 13:54:14 -0700 X-IronPort-AV: E=Sophos;i="5.90,254,1643702400"; d="scan'208";a="644899572" Received: from lpfafma-mobl.amr.corp.intel.com (HELO guptapa-desk) ([10.209.17.36]) by fmsmga003-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 Apr 2022 13:54:13 -0700 Date: Tue, 12 Apr 2022 13:54:11 -0700 From: Pawan Gupta To: Jon Kohler Cc: Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Andi Kleen , Tony Luck , linux-kernel@vger.kernel.org, dave.hansen@intel.com, Borislav Petkov , Neelima Krishnan , "kvm @ vger . kernel . org" Subject: Re: [PATCH v2] x86/tsx: fix KVM guest live migration for tsx=on Message-ID: <20220412205411.m7n2gnon3ai7wobm@guptapa-desk> References: <20220411180131.5054-1-jon@nutanix.com> <20220411200703.48654-1-jon@nutanix.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Disposition: inline In-Reply-To: <20220411200703.48654-1-jon@nutanix.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Apr 11, 2022 at 04:07:01PM -0400, Jon Kohler wrote: >Move automatic disablement for TSX microcode deprecation from tsx_init() to >x86_get_tsx_auto_mode(), such that systems with tsx=on will continue to >see the TSX CPU features (HLE, RTM) even on updated microcode. > >KVM live migration could be possibly be broken in 5.14+ commit 293649307ef9 >("x86/tsx: Clear CPUID bits when TSX always force aborts"). Consider the >following scenario: > >1. KVM hosts clustered in a live migration capable setup. >2. KVM guests have TSX CPU features HLE and/or RTM presented. >3. One of the three maintenance events occur: >3a. An existing host running kernel >= 5.14 in the pool updated with the > new microcode. >3b. A new host running kernel >= 5.14 is commissioned that already has the > microcode update preloaded. >3c. All hosts are running kernel < 5.14 with microcode update already > loaded and one existing host gets updated to kernel >= 5.14. >4. After maintenance event, the impacted host will not have HLE and RTM > exposed, and live migrations with guests with TSX features might not > migrate. Which part was this reproduced on? AFAIK server parts(except for some Intel Xeon E3s) did not get such microcode update. Thanks, Pawan