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=-11.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 73DDBC432BE for ; Thu, 2 Sep 2021 12:15:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4ED2E60295 for ; Thu, 2 Sep 2021 12:15:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1343940AbhIBMQx (ORCPT ); Thu, 2 Sep 2021 08:16:53 -0400 Received: from mail.kernel.org ([198.145.29.99]:36486 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1343984AbhIBMQw (ORCPT ); Thu, 2 Sep 2021 08:16:52 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id A954A60F90; Thu, 2 Sep 2021 12:15:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1630584954; bh=hr+t/bJ+QD4jlEcI9TsTp6H1aIJD4dtF+RqEdbB6Hrs=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=Xcn+mpNutq0ztqFE9/Cl8RHOuDeLeYGfQIxYWM8uTCKRAnO9OgXIp/UtD3YBcAaYO lrHqhjB2UHFKzm1grkYptjY250P7pYtuOlo9fX8QnAx+Hl6fdLEPyyHKxwIVa7pD6J iLXQSXrMjBnOoGt0BIpDVkd8b9j1Z7EQY7H7ZwKzKLgczpFnHXacS28g624cq1QPfI klu8+iKpyeCMe1Uiv8ZKQXgLZeCGLWtBwj4dtIfoG6zOUGbBIl04i7KoKajRwwiqaj nQQ9Tt/CMCCMzcmJqq5IgRbF+QfI36ipK/MOMDLX65kothi8gWb4ZAnqiwE6Ts+CR6 Rq0Civj3ajWhQ== Message-ID: <41e9b099f6492c389b3ed3bbe107d61804a307e9.camel@kernel.org> Subject: Re: [PATCH v3 2/2] x86/sgx: Add SGX_MemTotal to /proc/meminfo From: Jarkko Sakkinen To: Kai Huang Cc: linux-sgx@vger.kernel.org, Dave Hansen , Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org, "H. Peter Anvin" , Jonathan Corbet , Andy Lutomirski , Peter Zijlstra , Shuah Khan , linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org Date: Thu, 02 Sep 2021 15:15:51 +0300 In-Reply-To: <20210901174705.3b1a943ef8c4bb09323c6d76@intel.com> References: <20210825235234.153013-1-jarkko@kernel.org> <20210825235234.153013-2-jarkko@kernel.org> <20210826141959.5f13ff3c9c560c23b58443b1@intel.com> <54923ac01fc303e5105cadca06b7c5cbd322d815.camel@kernel.org> <20210828000335.1d40dfff0f408b2d91467491@intel.com> <04b90a702328712204430db604b2a92ddfe8f990.camel@kernel.org> <20210901173322.78f94b694b4be6b1225bee98@intel.com> <6a9fccdb6a458960e43a63afcce87cc62184adf9.camel@kernel.org> <20210901174705.3b1a943ef8c4bb09323c6d76@intel.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.36.5-0ubuntu1 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org On Wed, 2021-09-01 at 17:47 +1200, Kai Huang wrote: > On Wed, 01 Sep 2021 08:41:12 +0300 Jarkko Sakkinen wrote: > > On Wed, 2021-09-01 at 17:33 +1200, Kai Huang wrote: > > > On Wed, 01 Sep 2021 05:02:45 +0300 Jarkko Sakkinen wrote: > > > > On Sat, 2021-08-28 at 00:03 +1200, Kai Huang wrote: > > > > > > > > -/* The free page list lock protected variables prepend the= lock. */ > > > > > > > > +/* The number of usable EPC pages in the system. */ > > > > > > > > +unsigned long sgx_nr_all_pages; > > > > > > > > + > > > > > > > > +/* The number of free EPC pages in all nodes. */ > > > > > > > > static unsigned long sgx_nr_free_pages; > > > > > > > > =20 > > > > > > > > /* Nodes with one or more EPC sections. */ > > > > > > > > @@ -656,6 +659,8 @@ static bool __init sgx_setup_epc_sectio= n(u64 phys_addr, u64 size, > > > > > > > > list_add_tail(§ion->pages[i].list, &sgx_dirty_page_l= ist); > > > > > > > > } > > > > > > > > =20 > > > > > > > > + sgx_nr_all_pages +=3D nr_pages; > > > > > > > > + > > > > > > >=20 > > > > > > > EPC sections can be freed again in sgx_init() after they are = successfully > > > > > > > initialized, when any further initialization fails (i.e. when= fails to create > > > > > > > ksgxd, or fails to register /dev/sgx_provision). In which ca= se, I think > > > > > > > sgx_nr_all_pages should also be cleared. But current sgx_ini= t() seems doesn't > > > > > > > reset it. Do you need to fix that too? > > > > > >=20 > > > > > > sgx_nr_all_pages tells just the total pages in the system, i.e.= it's a constant. > > > > > >=20 > > > > > > Maybe a rename to "sgx_nr_total_pages" would be a good idea? Wo= uld match with > > > > > > the meminfo field better too. > > > > >=20 > > > > > I don't have preference on name. I just think if there's no actu= al user of > > > > > EPC (when both driver and KVM SGX cannot be enabled), it's pointl= ess to print > > > > > number of EPC pages. > > > >=20 > > > > I'd presume that you refer to the code, which prints the number of = *bytes* in > > > > the system because code printing the number of pages does not exist= in this > > > > patch set. > > > >=20 > > > > I have troubles the decipher your statement. > > > >=20 > > > > You think that only if both the driver and KVM are *both* enabled, = only then > > > > it makes sense to have this information available for sysadmin? > > >=20 > > > Only if at least one of them is enabled. > >=20 > > OK, thank you, that does make sense. > >=20 > > What would happen if neither is enabled is that SGX_MemTotal would > > state that there is zero bytes of EPC.=20 >=20 > This is the problem I pointed out at the beginning, that (if I read code > correctly), it seems your current patch doesn't clear sgx_nr_all_pages wh= en > neither is enabled (in sgx_init() in sgx/main.c). It's initialized to zero, so are you talking about fallback when something fails? /Jarkko