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 lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id C2FDDC43334 for ; Wed, 13 Jul 2022 07:50:43 +0000 (UTC) Received: from localhost ([::1]:46818 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1oBX8s-0006lt-8x for qemu-devel@archiver.kernel.org; Wed, 13 Jul 2022 03:50:42 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:60286) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1oBX72-00063p-CI for qemu-devel@nongnu.org; Wed, 13 Jul 2022 03:48:48 -0400 Received: from mga11.intel.com ([192.55.52.93]:36264) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1oBX6z-0001m0-1T for qemu-devel@nongnu.org; Wed, 13 Jul 2022 03:48:46 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1657698525; x=1689234525; h=date:from:to:cc:subject:message-id:reply-to:references: mime-version:in-reply-to; bh=nUfcHt/iaf3oMSfMyzHxGwWsSmqpbvlJ2JFwYR1oe/M=; b=Dlk8uQwbPtKSwMrvRmBAJaxNseP47/ieMwYEOvaKl3weU3lb3SMzgalX uBNiOyZM3g4zmLkIulI6oINdwfnZuF9L6oBYSGmlTOcxh61Q8RtNup6st n08yvb+XhYQEUDupSJXckIy8iVZjHu2DtfEGCBmEvRqdkTEf5AjZ+M93V JTFp63pyT6jQ9SdNf52zWYA4D/M32fcXoIY66Md2zLfaaNTLktKlW8tbS 3g2yqEj/8ynrNnMVF/JMLI8DqToJOKqXI9NSu12wvZXdsKSakdMZXncKi fXHL6MhzhBX8qFa5gYGqXLPTAgTyY4UKjLTDxzblvwVJZGRuHICdpknVM g==; X-IronPort-AV: E=McAfee;i="6400,9594,10406"; a="282693326" X-IronPort-AV: E=Sophos;i="5.92,267,1650956400"; d="scan'208";a="282693326" Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by fmsmga102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 13 Jul 2022 00:48:25 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.92,267,1650956400"; d="scan'208";a="685067167" Received: from chaop.bj.intel.com (HELO localhost) ([10.240.192.101]) by FMSMGA003.fm.intel.com with ESMTP; 13 Jul 2022 00:48:16 -0700 Date: Wed, 13 Jul 2022 15:44:58 +0800 From: Chao Peng To: "Gupta, Pankaj" Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org, linux-doc@vger.kernel.org, qemu-devel@nongnu.org, linux-kselftest@vger.kernel.org, Paolo Bonzini , Jonathan Corbet , Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org, "H . Peter Anvin" , Hugh Dickins , Jeff Layton , "J . Bruce Fields" , Andrew Morton , Shuah Khan , Mike Rapoport , Steven Price , "Maciej S . Szmigiero" , Vlastimil Babka , Vishal Annapurve , Yu Zhang , "Kirill A . Shutemov" , luto@kernel.org, jun.nakajima@intel.com, dave.hansen@intel.com, ak@linux.intel.com, david@redhat.com, aarcange@redhat.com, ddutile@redhat.com, dhildenb@redhat.com, Quentin Perret , Michael Roth , mhocko@suse.com, Muchun Song Subject: Re: [PATCH v7 04/14] mm/shmem: Support memfile_notifier Message-ID: <20220713074458.GB2831541@chaop.bj.intel.com> References: <20220706082016.2603916-1-chao.p.peng@linux.intel.com> <20220706082016.2603916-5-chao.p.peng@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Received-SPF: none client-ip=192.55.52.93; envelope-from=chao.p.peng@linux.intel.com; helo=mga11.intel.com X-Spam_score_int: -70 X-Spam_score: -7.1 X-Spam_bar: ------- X-Spam_report: (-7.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.082, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_HI=-5, SPF_HELO_NONE=0.001, SPF_NONE=0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Chao Peng Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Tue, Jul 12, 2022 at 08:02:34PM +0200, Gupta, Pankaj wrote: > On 7/6/2022 10:20 AM, Chao Peng wrote: > > From: "Kirill A. Shutemov" > > > > Implement shmem as a memfile_notifier backing store. Essentially it > > interacts with the memfile_notifier feature flags for userspace > > access/page migration/page reclaiming and implements the necessary > > memfile_backing_store callbacks. > > > > Signed-off-by: Kirill A. Shutemov > > Signed-off-by: Chao Peng > > --- > > include/linux/shmem_fs.h | 2 + > > mm/shmem.c | 109 ++++++++++++++++++++++++++++++++++++++- > > 2 files changed, 110 insertions(+), 1 deletion(-) ... > > +#ifdef CONFIG_MIGRATION > > +static int shmem_migrate_page(struct address_space *mapping, > > + struct page *newpage, struct page *page, > > + enum migrate_mode mode) > > +{ > > + struct inode *inode = mapping->host; > > + struct shmem_inode_info *info = SHMEM_I(inode); > > + > > + if (info->memfile_node.flags & MEMFILE_F_UNMOVABLE) > > + return -EOPNOTSUPP; > > + return migrate_page(mapping, newpage, page, mode); > > Wondering how well page migrate would work for private pages > on shmem memfd based backend? >From high level: - KVM unset MEMFILE_F_UNMOVABLE bit to indicate it capable of migrating a page. - Introduce new 'migrate' callback(s) to memfile_notifier_ops for KVM to register. - The callback is hooked to migrate_page() here. - Once page migration requested, shmem calls into the 'migrate' callback(s) to perform additional steps for encrypted memory (For TDX we will call TDH.MEM.PAGE.RELOCATE). Chao > > > +} > > +#endif > > + > > const struct address_space_operations shmem_aops = { > > .writepage = shmem_writepage, > > .dirty_folio = noop_dirty_folio, > > @@ -3814,7 +3872,7 @@ const struct address_space_operations shmem_aops = { > > .write_end = shmem_write_end, > > #endif > > #ifdef CONFIG_MIGRATION > > - .migratepage = migrate_page, > > + .migratepage = shmem_migrate_page, > > #endif > > .error_remove_page = shmem_error_remove_page, > > }; > > @@ -3931,6 +3989,51 @@ static struct file_system_type shmem_fs_type = { > > .fs_flags = FS_USERNS_MOUNT, > > };