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=-11.2 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 04613C433E6 for ; Wed, 10 Mar 2021 15:12:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C380E64F5F for ; Wed, 10 Mar 2021 15:12:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232841AbhCJPMC (ORCPT ); Wed, 10 Mar 2021 10:12:02 -0500 Received: from mail.kernel.org ([198.145.29.99]:47552 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232405AbhCJPLf (ORCPT ); Wed, 10 Mar 2021 10:11:35 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 79FB364F4C; Wed, 10 Mar 2021 15:11:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1615389095; bh=GrnU7hctx6M3VdWoZiGqdmasQZGYP8izzqK/3P5/BYY=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=kSQVsW7ohF2rlCLhswvfcBGIb8wDMAngSd4+oMyCLngilh5Mfddkh2PvC65FniR1P YHNSUyllKFGbTdug0H0NcB5LmXhYW3YJhu/1MwDgaB850ho9Jjg33QrHMyknYuEjQW 6RkxoWpFc185+C5VpkVhcQnfX+Dms6GQKOftBenzeYxLlN95srjMlQop0GXzVNUnk2 SQC59UYLMZTfCg4YAyADctetIa9sHcIisk93RUtUWFAjrjlyhpvWtPsZEFuH4f6TI+ dSKbMQnvNvXee5KTerjyNWAQPFhd7F8pUuuj//cOOPXPYja6P8ncB7Gnyqy572t85U +Vzcd5cS/KlEQ== Date: Wed, 10 Mar 2021 17:11:10 +0200 From: Jarkko Sakkinen To: Dave Hansen Cc: linux-sgx@vger.kernel.org, Dave Hansen , Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org, "H. Peter Anvin" , linux-kernel@vger.kernel.org Subject: Re: [PATCH v3 2/5] x86/sgx: Use sgx_free_epc_page() in sgx_reclaim_pages() Message-ID: References: <20210303150323.433207-1-jarkko@kernel.org> <20210303150323.433207-3-jarkko@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Mar 03, 2021 at 08:59:17AM -0800, Dave Hansen wrote: > On 3/3/21 7:03 AM, Jarkko Sakkinen wrote: > > diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c > > index 52d070fb4c9a..ed99c60024dc 100644 > > --- a/arch/x86/kernel/cpu/sgx/main.c > > +++ b/arch/x86/kernel/cpu/sgx/main.c > > @@ -305,7 +305,6 @@ static void sgx_reclaim_pages(void) > > { > > struct sgx_epc_page *chunk[SGX_NR_TO_SCAN]; > > struct sgx_backing backing[SGX_NR_TO_SCAN]; > > - struct sgx_epc_section *section; > > struct sgx_encl_page *encl_page; > > struct sgx_epc_page *epc_page; > > pgoff_t page_index; > > @@ -378,11 +377,7 @@ static void sgx_reclaim_pages(void) > > kref_put(&encl_page->encl->refcount, sgx_encl_release); > > epc_page->flags &= ~SGX_EPC_PAGE_RECLAIMER_TRACKED; > > > > - section = &sgx_epc_sections[epc_page->section]; > > - spin_lock(§ion->lock); > > - list_add_tail(&epc_page->list, §ion->page_list); > > - section->free_cnt++; > > - spin_unlock(§ion->lock); > > + sgx_free_epc_page(epc_page); > > } > > } > > In current upstream (3fb6d0e00e), sgx_free_epc_page() calls __eremove(). > This code does not call __eremove(). That seems to be changing > behavior where none was intended. EREMOVE does not matter here, as it doesn't in almost all most of the sites where sgx_free_epc_page() is used in the driver. It does nothing to an uninitialized pages. The two patches that I posted originally for Kai's series took EREMOVE out of sgx_free_epc_page() and put an explicit EREMOVE where it is actually needed, but for reasons unknown to me, that change is gone. Replacing the ad-hoc code with sgx_free_epc_page() is absolutely the right action to take because it follows the pattern how sgx_free_epc_page() is used in the driver. For reference: https://lore.kernel.org/linux-sgx/20210113233541.17669-1-jarkko@kernel.org/ > Was this, perhaps, based on top of Kai's series that changes the > behavior of sgx_free_epc_page()? I did not refer to that patch series. /Jarkko