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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 69798C433FE for ; Fri, 25 Feb 2022 16:46:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243183AbiBYQqq (ORCPT ); Fri, 25 Feb 2022 11:46:46 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50552 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240744AbiBYQqp (ORCPT ); Fri, 25 Feb 2022 11:46:45 -0500 Received: from mga18.intel.com (mga18.intel.com [134.134.136.126]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7E64A22D648 for ; Fri, 25 Feb 2022 08:46:12 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1645807572; x=1677343572; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=MCgw0LWT1+2QvtoTlKlxzXXA4QkTFgfXGwz78fZbxIk=; b=dMykKfp4O68B3Mglq+bSSrEi7GbGO7JCBjvF9m5P5arPAkrzzI2kfix2 7L5DDWtH3MNMT7yNdawvBR+MzUGb4fWniSmZbFNnneaERf/rOYcEteTWv X6epEejkCybr2VWfoxYJEC48KvwzgQcq0iMZgCETvi7qbyEdFbcvmjoiV 25Sgy1QSOXTbWEcaO804MzDe0rBCgQlpBWQC1X8d6e1mqdJePpUoidqRO 4tmauxKM1/8NlblA1nMSpRyKClfqYl/aYE9XC854Beh7QmFUOk3gnFdVr Q0j45IkfFh3b/wsnH7jUdtcbZvvWRThzsO7PPSI5PGSdotrhhhkObQvT2 g==; X-IronPort-AV: E=McAfee;i="6200,9189,10268"; a="236038244" X-IronPort-AV: E=Sophos;i="5.90,136,1643702400"; d="scan'208";a="236038244" Received: from orsmga002.jf.intel.com ([10.7.209.21]) by orsmga106.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 25 Feb 2022 08:45:56 -0800 X-IronPort-AV: E=Sophos;i="5.90,136,1643702400"; d="scan'208";a="506742962" Received: from skannan1-mobl1.amr.corp.intel.com (HELO localhost) ([10.209.142.223]) by orsmga002-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 25 Feb 2022 08:45:52 -0800 Date: Fri, 25 Feb 2022 08:45:51 -0800 From: Ira Weiny To: lsf-pc@lists.linux-foundation.org Cc: linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, ira.weiny@intel.com Subject: [LSF/MM/BPF TOPIC] PKS for the page cache and beyond Message-ID: References: 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-fsdevel@vger.kernel.org Resend due to typo in tag. s/PPF/BPF/ However, I also realized one should fill out the google form now. I'll do that straight away. Thanks, Ira On Fri, Feb 25, 2022 at 08:10:30AM -0800, Ira Weiny wrote: > Hello, > > Protection Key Supervisor (PKS) presents a way to control access to a large > domain of memory quickly, without a page table walk or TLB flush, as well as > with finer granularity; allowing protection control on individual threads. > > Multiple areas of memory have been identified as candidates to be protected > with PKS. These include the initial use case persistent memory (PMEM), page > tables[1], kernel secret keys[2], and the page cache.[3] Like PMEM the page > cache presents a significant surface area where stray writes, or other bugs, > could corrupt data permanently. > > I would like to discuss the ramifications of being able to change memory > permissions in this new way. While PKS has a lot to offer it does not come for > free. One trade off is the loss of direct access via page_address() in > !HIGHMEM builds. > > Already PMEM's faced challenges in the leverage of kmap/kunmap. While the page > cache should be able to leverage this work, this is driving a redefinition of > what kmap means. Especially since the HIGHMEM use case is increasingly > meaningless on modern machines. > > Ira Weiny > > [1] https://lore.kernel.org/lkml/20210830235927.6443-2-rick.p.edgecombe@intel.com/ > [2] https://lore.kernel.org/lkml/20201009201410.3209180-3-ira.weiny@intel.com/ > [3] https://lwn.net/Articles/883352/