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=-13.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,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 5D02EC5DF63 for ; Wed, 6 Nov 2019 22:02:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 323332173E for ; Wed, 6 Nov 2019 22:02:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726798AbfKFWCm (ORCPT ); Wed, 6 Nov 2019 17:02:42 -0500 Received: from mga02.intel.com ([134.134.136.20]:63367 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726779AbfKFWCl (ORCPT ); Wed, 6 Nov 2019 17:02:41 -0500 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from fmsmga007.fm.intel.com ([10.253.24.52]) by orsmga101.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 06 Nov 2019 14:02:41 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.68,275,1569308400"; d="scan'208";a="201226488" Received: from ksterken-mobl6.amr.corp.intel.com (HELO localhost) ([10.252.10.117]) by fmsmga007.fm.intel.com with ESMTP; 06 Nov 2019 14:02:39 -0800 Date: Thu, 7 Nov 2019 00:02:37 +0200 From: Jarkko Sakkinen To: Sean Christopherson Cc: linux-sgx@vger.kernel.org Subject: Re: [PATCH for v24 1/3] x86/sgx: Use GFP_KERNEL for allocations Message-ID: <20191106220237.GA11526@linux.intel.com> References: <20191104200141.5385-1-jarkko.sakkinen@linux.intel.com> <20191104204602.GA5960@linux.intel.com> <20191104222658.GA3606@linux.intel.com> <20191105021720.GE5960@linux.intel.com> <20191106215438.GA8715@linux.intel.com> <20191106215942.GA10732@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191106215942.GA10732@linux.intel.com> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-sgx-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-sgx@vger.kernel.org On Wed, Nov 06, 2019 at 11:59:42PM +0200, Jarkko Sakkinen wrote: > On Wed, Nov 06, 2019 at 11:54:38PM +0200, Jarkko Sakkinen wrote: > > On Mon, Nov 04, 2019 at 06:17:20PM -0800, Sean Christopherson wrote: > > > On Tue, Nov 05, 2019 at 12:26:58AM +0200, Jarkko Sakkinen wrote: > > > > On Mon, Nov 04, 2019 at 12:46:02PM -0800, Sean Christopherson wrote: > > > > > On Mon, Nov 04, 2019 at 10:01:39PM +0200, Jarkko Sakkinen wrote: > > > > > > The reasoning is the same as in > > > > > > > > > > > > http://git.infradead.org/users/jjs/linux-tpmdd.git/commit/abd55954f91a3aacc1d260d2411cf776ec4d5fd2 > > > > > > > > > > > > Signed-off-by: Jarkko Sakkinen > > > > > > --- > > > > > > arch/x86/kernel/cpu/sgx/ioctl.c | 4 ++-- > > > > > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > > > > > > > > > diff --git a/arch/x86/kernel/cpu/sgx/ioctl.c b/arch/x86/kernel/cpu/sgx/ioctl.c > > > > > > index 5b28a9c0cb68..d53aee5a64c1 100644 > > > > > > --- a/arch/x86/kernel/cpu/sgx/ioctl.c > > > > > > +++ b/arch/x86/kernel/cpu/sgx/ioctl.c > > > > > > @@ -259,7 +259,7 @@ static long sgx_ioc_enclave_create(struct sgx_encl *encl, void __user *arg) > > > > > > if (copy_from_user(&ecreate, arg, sizeof(ecreate))) > > > > > > return -EFAULT; > > > > > > > > > > > > - secs_page = alloc_page(GFP_HIGHUSER); > > > > > > + secs_page = alloc_page(GFP_KERNEL); > > > > > > if (!secs_page) > > > > > > return -ENOMEM; > > > > > > > > > > > > @@ -674,7 +674,7 @@ static long sgx_ioc_enclave_init(struct sgx_encl *encl, void __user *arg) > > > > > > if (copy_from_user(&einit, arg, sizeof(einit))) > > > > > > return -EFAULT; > > > > > > > > > > > > - initp_page = alloc_page(GFP_HIGHUSER); > > > > > > + initp_page = alloc_page(GFP_KERNEL); > > > > > > > > > > Would it make sense to use GFP_KERNEL_ACCOUNT? The accounting would be > > > > > weird for the case where userspace is using a builder process, but even in > > > > > that case it's not flat out wrong to account per-enclave memory allocations. > > > > > > > > I did not find a single call site that would use that for allocating > > > > memory for function-internal data. > > > > > > Actually, the fact that the allocations are transient is an even better > > > argument for accounting the memory, as the weirdness I was referring to > > > doesn't exist for the builder concept. > > > > > > But looking more closely, Documentation/core-api/memory-allocation.rst > > > states: > > > > > > * Untrusted allocations triggered from userspace should be a subject > > > of kmem accounting and must have ``__GFP_ACCOUNT`` bit set. There > > > is the handy ``GFP_KERNEL_ACCOUNT`` shortcut for ``GFP_KERNEL`` > > > allocations that should be accounted. > > > > > > That means all uses of GFP_KERNEL except in sgx_alloc_epc_section() should > > > be converted to GFP_KERNEL_ACCOUNTED. As is, depending on fd limits[*], a > > > single process can easily burn through multiple GBs of memory simply by > > > opening /dev/sgx/enclave in a loop. > > > > What does the documentation mean by untrusted allocaton? > > > > __GFP_ACCOUNT kernel and GFP_KERNEL_ACCOUNT are both quite alien flags > > to me as is kmemcg. Things that I know that exist but have never had to > > deal with them. > > > > Looking at the kernel source code they rarely get used. Many drivers > > have process bound data structures but none of the drivers use these > > flags. I'm wondering why. > > > > Why sgx_alloc_epc_section() is a use case given that it is something > > that allocates memory for the global EPC database? > > > > > [*] AFAICT, systemd is upping the max number of open files to 1M on my > > > systems. I don't _think_ I changed a setting anywhere? > > Anyway, the tree is now updated: > > diff --git a/arch/x86/kernel/cpu/sgx/ioctl.c b/arch/x86/kernel/cpu/sgx/ioctl.c > index 5b82670bb79a..d53aee5a64c1 100644 > --- a/arch/x86/kernel/cpu/sgx/ioctl.c > +++ b/arch/x86/kernel/cpu/sgx/ioctl.c > @@ -259,7 +259,7 @@ static long sgx_ioc_enclave_create(struct sgx_encl *encl, void __user *arg) > if (copy_from_user(&ecreate, arg, sizeof(ecreate))) > return -EFAULT; > > - secs_page = alloc_page(GFP_HIGHUSER); > + secs_page = alloc_page(GFP_KERNEL); > if (!secs_page) > return -ENOMEM; > > @@ -427,12 +427,20 @@ static int sgx_encl_add_page(struct sgx_encl *encl, > > if (addp->flags & SGX_PAGE_MEASURE) { > ret = __sgx_encl_extend(encl, epc_page); > - if (ret) > + > + /* > + * Destroy the enclave if EEXTEND fails, EADD can't be undone. > + * Note, destroy() also frees the resources for the added page. > + */ > + if (ret) { > sgx_encl_destroy(encl); > - else > - sgx_mark_page_reclaimable(encl_page->epc_page); > + goto out_unlock; > + } > } > > + sgx_mark_page_reclaimable(encl_page->epc_page); > + > +out_unlock: > mutex_unlock(&encl->lock); > up_read(¤t->mm->mmap_sem); > return ret; > @@ -666,7 +674,7 @@ static long sgx_ioc_enclave_init(struct sgx_encl *encl, void __user *arg) > if (copy_from_user(&einit, arg, sizeof(einit))) > return -EFAULT; > > - initp_page = alloc_page(GFP_HIGHUSER); > + initp_page = alloc_page(GFP_KERNEL); > if (!initp_page) > return -ENOMEM; > > Hope that all the updates will be fairly localized :-) Also removed some patches on top that were pushed by accident (patches under review). /Jarkko