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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 46F32C433EF for ; Sun, 7 Nov 2021 18:06:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2D88F6108E for ; Sun, 7 Nov 2021 18:06:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230310AbhKGSJ2 (ORCPT ); Sun, 7 Nov 2021 13:09:28 -0500 Received: from mail.kernel.org ([198.145.29.99]:58260 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230234AbhKGSJ2 (ORCPT ); Sun, 7 Nov 2021 13:09:28 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id C4FF461074; Sun, 7 Nov 2021 18:06:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1636308405; bh=aWDSKq24BEhQZHeIVmLKMzpNb1qnm7PcMMkOet0HbOs=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=YyoV6PFTEMjfGZnwHwoSrRHiYSp0T+aYNPNIX7ECRTHdnT3KDL6VPww9Dh3VcL22s QJ2D/6jmHGkqK5pcxt3eMgqZoak3DqpXQb9BtTHik6X0WTRzC1a4feQOqynCj9E5qj TKbGnOsgpDN4sVeUqqmuBUfhjZzTkB/LstTUEjsaH7SWztpqWRnUJt4gNkOybGomEu yD/nzxBS9+a1S316dbdI0LfxExalcle1xBtuPC+P5Pn62y9+Wqx9QmoI9D9KUv6WsF cSGJbgnfEa3uhApFubysKNXUQixdyaEZgU3b0CG3b/E2iL0ihqLMUdKJeltmicHCUC QlSgcu0xbQYow== Date: Sun, 7 Nov 2021 20:06:42 +0200 From: Jarkko Sakkinen To: Dave Hansen Cc: Dave Hansen , Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org, "H. Peter Anvin" , Jethro Beekman , Sean Christopherson , reinette.chatre@intel.com, tony.luck@intel.com, nathaniel@profian.com, stable@vger.kernel.org, Borislav Petkov , linux-sgx@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] x86/sgx: Free backing memory after faulting the enclave page Message-ID: References: <20211103232238.110557-1-jarkko@kernel.org> <7c122a82-e418-0bce-8f67-cbaa15abc9b9@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <7c122a82-e418-0bce-8f67-cbaa15abc9b9@intel.com> Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On Thu, Nov 04, 2021 at 03:38:55PM -0700, Dave Hansen wrote: > On 11/3/21 4:22 PM, Jarkko Sakkinen wrote: > > --- a/arch/x86/kernel/cpu/sgx/encl.c > > +++ b/arch/x86/kernel/cpu/sgx/encl.c > > @@ -22,6 +22,7 @@ static int __sgx_encl_eldu(struct sgx_encl_page *encl_page, > > { > > unsigned long va_offset = encl_page->desc & SGX_ENCL_PAGE_VA_OFFSET_MASK; > > struct sgx_encl *encl = encl_page->encl; > > + struct inode *inode = file_inode(encl->backing); > > struct sgx_pageinfo pginfo; > > struct sgx_backing b; > > pgoff_t page_index; > > @@ -60,6 +61,9 @@ static int __sgx_encl_eldu(struct sgx_encl_page *encl_page, > > > > sgx_encl_put_backing(&b, false); > > > > + /* Free the backing memory. */ > > + shmem_truncate_range(inode, PFN_PHYS(page_index), PFN_PHYS(page_index) + PAGE_SIZE - 1); > > + > > return ret; > > } > > This also misses tearing down the backing storage if it is in place at > sgx_encl_release(). Hmm... sgx_encl_release() does fput(). Isn't that enough to tear it down, or does it require explicit truncate, i.e. something like shmem_truncate_range(file_inode(encl->backing), encl->base, encl->size - 1); > Does a entry->epc_page==NULL page in there guarantee that it has backing > storage? Yes, it is an invariant. That what I was thinking to use for PCMD: iterate 32 pages and check if they have a faulted page. /Jarkko