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=-16.6 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,HK_RANDOM_FROM,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,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 6A87DC433F5 for ; Tue, 7 Sep 2021 02:08:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 45A9D610E9 for ; Tue, 7 Sep 2021 02:08:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242302AbhIGCJP (ORCPT ); Mon, 6 Sep 2021 22:09:15 -0400 Received: from mga11.intel.com ([192.55.52.93]:47530 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230250AbhIGCJN (ORCPT ); Mon, 6 Sep 2021 22:09:13 -0400 X-IronPort-AV: E=McAfee;i="6200,9189,10099"; a="216916157" X-IronPort-AV: E=Sophos;i="5.85,273,1624345200"; d="scan'208";a="216916157" Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by fmsmga102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 06 Sep 2021 19:08:06 -0700 X-IronPort-AV: E=Sophos;i="5.85,273,1624345200"; d="scan'208";a="605024733" Received: from xiaoyaol-mobl.ccr.corp.intel.com (HELO [10.239.13.122]) ([10.239.13.122]) by fmsmga001-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 06 Sep 2021 19:08:04 -0700 Subject: Re: [PATCH] x86/tsx: clear RTM and HLE when MSR_IA32_TSX_CTRL is not supported To: Hao Peng , Borislav Petkov Cc: tglx@linutronix.de, mingo@redhat.com, x86@kernel.org, linux-kernel@vger.kernel.org, Pawan Gupta References: From: Xiaoyao Li Message-ID: Date: Tue, 7 Sep 2021 10:08:01 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Firefox/78.0 Thunderbird/78.13.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 9/7/2021 9:47 AM, Hao Peng wrote: > On Mon, Sep 6, 2021 at 5:30 PM Borislav Petkov wrote: >> >> On Mon, Sep 06, 2021 at 10:46:05AM +0800, Hao Peng wrote: >>> If hypervisor does not support MSR_IA32_TSX_CTRL, but guest supports >>> RTM and HLE features, it will affect TAA mitigation. >>> >>> Signed-off-by: Peng Hao >>> --- >>> arch/x86/kernel/cpu/tsx.c | 7 +++++++ >>> 1 file changed, 7 insertions(+) >>> >>> diff --git a/arch/x86/kernel/cpu/tsx.c b/arch/x86/kernel/cpu/tsx.c >>> index 9c7a5f049292..5e852c14fef2 100644 >>> --- a/arch/x86/kernel/cpu/tsx.c >>> +++ b/arch/x86/kernel/cpu/tsx.c >>> @@ -122,6 +122,13 @@ void __init tsx_init(void) >>> >>> if (!tsx_ctrl_is_supported()) { >>> tsx_ctrl_state = TSX_CTRL_NOT_SUPPORTED; >>> + >>> + /* If hypervisor does not support MSR_IA32_TSX_CTRL emulation, >>> + * but guest supports RTM and HLE features, it will affect TAA >>> + * （tsx_async_abort）mitigation. >>> + */ >>> + setup_clear_cpu_cap(X86_FEATURE_RTM); >>> + setup_clear_cpu_cap(X86_FEATURE_HLE); anyway, IMHO, we shouldn't do anything here for TAA. It should be in taa_select_mitigation() >>> return; >>> } >> >> How does that even happen - the hypervisor does not support the MSR but >> "guest supports" TSX features?! >> >> I guess the guest is detecting it wrong. >> >> What hypervisor, what guest, how do I reproduce? >> > hypervisor is kvm, guest is linux too. >> Please give full details. >> > The host I used is kernel-5.4, and guest is kernel-5.13. > MSR_IA32_TSX_CTRL is exposed > to guest and guest to support RTM and HLE features, no direct > dependence. at the qemu I > started guest with -cpu host-model. > I have viewed the code of kernel-5.4, and MSR_IA32_TSX_CTRL is not > exposed to guest. Does guest see TAA_NO bit? > Thanks. >> -- >> Regards/Gruss, >> Boris. >> >> https://people.kernel.org/tglx/notes-about-netiquette