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 E67D7CA0FE3 for ; Fri, 1 Sep 2023 01:29:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1348054AbjIAB3J (ORCPT ); Thu, 31 Aug 2023 21:29:09 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40902 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1348044AbjIAB3H (ORCPT ); Thu, 31 Aug 2023 21:29:07 -0400 Received: from mgamail.intel.com (mgamail.intel.com [192.55.52.115]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6F8C2E70 for ; Thu, 31 Aug 2023 18:28:46 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1693531726; x=1725067726; h=date:from:to:cc:subject:message-id:reply-to:references: mime-version:in-reply-to; bh=jcNJ3QYMrTqoK9L+yVuOb08DWygtNbDciY8Xr0vyAjs=; b=XCpauqdHj623g6K17aGsoa4HIKz5srC/M6GqfB6ZZN2v3VPApIwOMx9A PrRKxFM2aLShCcj3Vk8q4Hqy+mr+ovyhBIlyjYk9n3KqJZwlpRdCD0pV0 wDTPOAApq5/HsUJV5rnhWW1RBJ7tzCUOWjhg5TuCoeys31vL5eOdi9Q3K TEdE3j1Ox8C58X5mDz56wk3TmCgqk8pN3etersemRPxgNW2eBQbYGn/CT DtjOpRXQ5+b0zZrWQX02nHaFkrf6Onhf7QPG/q1Yw/diyFrawq/zCnzms JP364xLmj7HBoz6LrvXrvuP5Jv8mtkiEqZZmT2ji7xAuvL1PJ0vIafqx+ Q==; X-IronPort-AV: E=McAfee;i="6600,9927,10819"; a="376045535" X-IronPort-AV: E=Sophos;i="6.02,218,1688454000"; d="scan'208";a="376045535" Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by fmsmga103.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 31 Aug 2023 18:28:45 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10819"; a="805244416" X-IronPort-AV: E=Sophos;i="6.02,218,1688454000"; d="scan'208";a="805244416" Received: from chaop.bj.intel.com (HELO localhost) ([10.240.193.80]) by fmsmga008.fm.intel.com with ESMTP; 31 Aug 2023 18:28:41 -0700 Date: Fri, 1 Sep 2023 09:17:11 +0800 From: Chao Peng To: Sean Christopherson Cc: kvm@vger.kernel.org, Fuad Tabba , Yu Zhang , Vishal Annapurve , Ackerley Tng , Maciej Szmigiero , Vlastimil Babka , Quentin Perret , Michael Roth , Wang , Liam Merwick , Isaku Yamahata , "Kirill A . Shutemov" , Paolo Bonzini , Jorg Rodel , Vitaly Kuznetsov Subject: Re: [RFC PATCH v11 00/29] KVM: guest_memfd() and per-page attributes Message-ID: <20230901011711.GA673287@chaop.bj.intel.com> Reply-To: Chao Peng References: <20230718234512.1690985-1-seanjc@google.com> <20230829091233.GA72470@chaop.bj.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Thu, Aug 31, 2023 at 11:29:22AM -0700, Sean Christopherson wrote: > On Tue, Aug 29, 2023, Chao Peng wrote: > > On Fri, Aug 25, 2023 at 10:47:12AM -0700, Sean Christopherson wrote: > > > > > > > > > Filemap vs. xarray > > > ------------------ > > > This is the main item that needs attention. I don't want to merge guest_memfd() > > > without doing this comparison, as not using filemap means we don't need AS_UNMOVABLE. > > > Arguably we could merge a filemap implementation without AS_UNMOVABLE and just eat > > > the suboptimal behavior, but not waiting a little while longer to do everything we > > > can to get this right the first time seems ridiculous after we've been working on > > > this for literally years. > > > > > > Paolo was going to work on an axarray implementation, but AFAIK he hasn't done > > > anything yet. We (Google) don't have anyone available to work on an xarray > > > implementation for several weeks (at best), so if anyone has the bandwidth and > > > desire to take stab at an xarray implementation, please speak up. > > > > I can do some experiments in the following weeks on the xarray > > direction. I'm not quite confident I understood all what Paolo > > originally wanted to do, so questions may have. > > FYI, I jumped the gun, sounds like Paolo got far enough along to form a strong > opinion[*]. Yeah, I see that, that is a good news actually, then we can go ahead with the current filemap one. I personally think these mm touchpoints are not a big deal when compared to previous versions, most part we are just using the APIs. > > Thanks for volunteering though, much appreciated! NP, any collaboration is to make this lasting years series merge earlier. Chao > > [*] https://lore.kernel.org/all/CABgObfay4FKV=foWLZzAWaC2kVHRnF1ib+6NC058QVZVFhGeyA@mail.gmail.com