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=-8.3 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 C4BDEECE58B for ; Sat, 5 Oct 2019 16:44:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9BA4722475 for ; Sat, 5 Oct 2019 16:44:16 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=alien8.de header.i=@alien8.de header.b="DoQZoM5U" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729522AbfJEQoQ (ORCPT ); Sat, 5 Oct 2019 12:44:16 -0400 Received: from mail.skyhub.de ([5.9.137.197]:34078 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725826AbfJEQoP (ORCPT ); Sat, 5 Oct 2019 12:44:15 -0400 Received: from zn.tnic (p200300EC2F1EF900329C23FFFEA6A903.dip0.t-ipconnect.de [IPv6:2003:ec:2f1e:f900:329c:23ff:fea6:a903]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.skyhub.de (SuperMail on ZX Spectrum 128k) with ESMTPSA id 11B1D1EC02C1; Sat, 5 Oct 2019 18:44:14 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=dkim; t=1570293854; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=J+YX1vtj2G53vkynUCkCYWZd/IUTyT9OXhsEBg1eZng=; b=DoQZoM5UATS94gv+/JIxMp7gtDdvOQUga0XbTeLs7V/1bbtlOAd1TdGtWpFLWEcdf8YPNa 1tRIVANOuAc0VtGgJBrkPjIG9NmSFwa9M0LS/SgOwen4P238AlOYnBiQHyOP2/4yydl+ew Z9Bjs54NYD4PmjtX+XDbRZvnPEQ3oh0= Date: Sat, 5 Oct 2019 18:44:08 +0200 From: Borislav Petkov To: Jarkko Sakkinen Cc: linux-kernel@vger.kernel.org, x86@kernel.org, linux-sgx@vger.kernel.org, akpm@linux-foundation.org, dave.hansen@intel.com, sean.j.christopherson@intel.com, nhorman@redhat.com, npmccallum@redhat.com, serge.ayoun@intel.com, shay.katz-zamir@intel.com, haitao.huang@intel.com, andriy.shevchenko@linux.intel.com, tglx@linutronix.de, kai.svahn@intel.com, josh@joshtriplett.org, luto@kernel.org, kai.huang@intel.com, rientjes@google.com, cedric.xing@intel.com Subject: Re: [PATCH v22 09/24] x86/sgx: Add functions to allocate and free EPC pages Message-ID: <20191005164408.GB25699@zn.tnic> References: <20190903142655.21943-1-jarkko.sakkinen@linux.intel.com> <20190903142655.21943-10-jarkko.sakkinen@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20190903142655.21943-10-jarkko.sakkinen@linux.intel.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Sep 03, 2019 at 05:26:40PM +0300, Jarkko Sakkinen wrote: > Add functions for grabbing EPC pages into use: > > * sgx_alloc_page(): Iterate the EPC sections and return the first free > page, or ERR_PTR(-ENOMEM) when no free pages are available. > * __sgx_free_page(): Return the page into uninitialized state and move > it back to the corresponding EPC section structure. Issues WARN() > when EREMOVE fails. > * sgx_free_page(): Return the page into uninitialized state and move > it back to the corresponding EPC section structure. Returns > ENCLS[EREMOVE] error code back to the caller. > > [1] Intel SDM: 40.3 INTEL® SGX SYSTEM LEAF FUNCTION REFERENCE > > Signed-off-by: Jarkko Sakkinen > Co-developed-by: Sean Christopherson > Signed-off-by: Sean Christopherson > --- > arch/x86/kernel/cpu/sgx/main.c | 90 ++++++++++++++++++++++++++++++++++ > arch/x86/kernel/cpu/sgx/sgx.h | 4 ++ > 2 files changed, 94 insertions(+) > > diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c > index e2317f6e4374..6b4727df72ca 100644 > --- a/arch/x86/kernel/cpu/sgx/main.c > +++ b/arch/x86/kernel/cpu/sgx/main.c > @@ -9,6 +9,7 @@ > #include > #include > #include "arch.h" > +#include "encls.h" > #include "sgx.h" > > struct sgx_epc_section sgx_epc_sections[SGX_MAX_EPC_SECTIONS]; > @@ -16,6 +17,95 @@ EXPORT_SYMBOL_GPL(sgx_epc_sections); > > int sgx_nr_epc_sections; > > +static struct sgx_epc_page *sgx_section_get_page( That fits into 80 cols (oh well, 81) and even if not, a trailing opening arg brace is ugly. > + struct sgx_epc_section *section) > +{ > + struct sgx_epc_page *page; > + > + if (!section->free_cnt) > + return NULL; > + > + page = list_first_entry(§ion->page_list, > + struct sgx_epc_page, list); That fits in 80-cols too. Why break it? > + list_del_init(&page->list); > + section->free_cnt--; > + return page; > +} > + > +/** > + * sgx_alloc_page - Allocate an EPC page > + * > + * Try to grab a page from the free EPC page list. > + * > + * Return: > + * a pointer to a &struct sgx_epc_page instance, > + * -errno on error > + */ > +struct sgx_epc_page *sgx_alloc_page(void) > +{ > + struct sgx_epc_section *section; > + struct sgx_epc_page *page; > + int i; > + > + for (i = 0; i < sgx_nr_epc_sections; i++) { > + section = &sgx_epc_sections[i]; > + spin_lock(§ion->lock); > + page = sgx_section_get_page(section); > + spin_unlock(§ion->lock); > + > + if (page) > + return page; > + } > + > + return ERR_PTR(-ENOMEM); > +} > +EXPORT_SYMBOL_GPL(sgx_alloc_page); That export gets removed later too. But you know already... > + > +/** > + * __sgx_free_page - Free an EPC page > + * @page: pointer a previously allocated EPC page > + * > + * EREMOVE an EPC page and insert it back to the list of free pages. > + * > + * Return: > + * 0 on success > + * SGX error code if EREMOVE fails > + */ > +int __sgx_free_page(struct sgx_epc_page *page) > +{ > + struct sgx_epc_section *section = sgx_epc_section(page); > + int ret; Shouldn't you be grabbing the lock here already? Or nothing can happen to that page from another thread after you ENCLS[EREMOVE] it and before it is added to the ->page_list of the section? > + > + ret = __eremove(sgx_epc_addr(page)); > + if (ret) > + return ret; > + > + spin_lock(§ion->lock); > + list_add_tail(&page->list, §ion->page_list); > + section->free_cnt++; > + spin_unlock(§ion->lock); > + > + return 0; > +} > +EXPORT_SYMBOL_GPL(__sgx_free_page); > + > +/** > + * sgx_free_page - Free an EPC page and WARN on failure > + * @page: pointer to a previously allocated EPC page > + * > + * EREMOVE an EPC page and insert it back to the list of free pages, and WARN > + * if EREMOVE fails. For use when the call site cannot (or chooses not to) > + * handle failure, i.e. the page is leaked on failure. > + */ > +void sgx_free_page(struct sgx_epc_page *page) > +{ > + int ret; > + > + ret = __sgx_free_page(page); > + WARN(ret > 0, "sgx: EREMOVE returned %d (0x%x)", ret, ret); That will potentially flood dmesg. Why are we even accommodating such callers? They either handle the error or they don't get to alloc EPC pages. There's also __must_check with which you can enforce the error code checking or we simply don't allow not handling failure. Fullstop. Thx. -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette