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=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS autolearn=no 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 95435C433E0 for ; Mon, 22 Mar 2021 20:44:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6872A619A1 for ; Mon, 22 Mar 2021 20:44:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231196AbhCVUoN (ORCPT ); Mon, 22 Mar 2021 16:44:13 -0400 Received: from mga09.intel.com ([134.134.136.24]:6375 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230401AbhCVUnm (ORCPT ); Mon, 22 Mar 2021 16:43:42 -0400 IronPort-SDR: pPvnHkauOfHFcap+6f3WR6TVnPbeWyrYRiXRGe8JFZhX2RTqrv69APW0ZzEAPBNQLpzJemnwtk ZJekEp/alsKQ== X-IronPort-AV: E=McAfee;i="6000,8403,9931"; a="190439916" X-IronPort-AV: E=Sophos;i="5.81,269,1610438400"; d="scan'208";a="190439916" Received: from orsmga004.jf.intel.com ([10.7.209.38]) by orsmga102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 22 Mar 2021 13:43:41 -0700 IronPort-SDR: 7OpqJlrd48XSOrSdb+msx2toQeYW7bM0OKsuOKo8ovXkhgg4AmURcTAP9jvf1G2ER8lB11nUNv F/1GMu2ednXg== X-IronPort-AV: E=Sophos;i="5.81,269,1610438400"; d="scan'208";a="524577166" Received: from zssigmon-mobl.amr.corp.intel.com (HELO khuang2-desk.gar.corp.intel.com) ([10.254.92.253]) by orsmga004-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 22 Mar 2021 13:43:38 -0700 Date: Tue, 23 Mar 2021 09:43:36 +1300 From: Kai Huang To: Paolo Bonzini Cc: Sean Christopherson , Borislav Petkov , kvm@vger.kernel.org, x86@kernel.org, linux-sgx@vger.kernel.org, linux-kernel@vger.kernel.org, jarkko@kernel.org, luto@kernel.org, dave.hansen@intel.com, rick.p.edgecombe@intel.com, haitao.huang@intel.com, tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com Subject: Re: [PATCH v3 03/25] x86/sgx: Wipe out EREMOVE from sgx_free_epc_page() Message-Id: <20210323094336.ab622e64594a79d54f55e3d7@intel.com> In-Reply-To: References: <062acb801926b2ade2f9fe1672afb7113453a741.1616136308.git.kai.huang@intel.com> <20210322181646.GG6481@zn.tnic> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.33; x86_64-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 22 Mar 2021 20:11:57 +0100 Paolo Bonzini wrote: > On 22/03/21 19:56, Sean Christopherson wrote: > > EREMOVE can only fail if there's a kernel or hardware bug (or a VMM bug if > > running as a guest). IME, nearly every kernel/KVM bug that I introduced that > > led to EREMOVE failure was also quite fatal to SGX, i.e. this is just the canary > > in the coal mine. > > That was my recollection as well from previous threads but, to be fair > to Boris, the commit message is a lot more scary (and, which is what > triggers me, puts the blame on KVM). It just says "KVM does not track > how guest pages are used, which means that SGX virtualization use of > EREMOVE might fail". I don't see the commit msg being scary. EREMOVE might fail but virtual EPC code can handle that. This is the reason to break out EREMOVE from original sgx_free_epc_page(), so virtual EPC code can have its own logic of handling EREMOVE failure.