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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1C1D9C3F6B0 for ; Wed, 24 Aug 2022 10:32:45 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 93CE36B0073; Wed, 24 Aug 2022 06:32:44 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 8C5756B0074; Wed, 24 Aug 2022 06:32:44 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 76593940007; Wed, 24 Aug 2022 06:32:44 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id 646846B0073 for ; Wed, 24 Aug 2022 06:32:44 -0400 (EDT) Received: from smtpin24.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id 344EE16012F for ; Wed, 24 Aug 2022 10:32:44 +0000 (UTC) X-FDA: 79834122648.24.AB9F15F Received: from mga01.intel.com (mga01.intel.com [192.55.52.88]) by imf22.hostedemail.com (Postfix) with ESMTP id 6B156C0037 for ; Wed, 24 Aug 2022 10:32:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1661337163; x=1692873163; h=date:from:to:cc:subject:message-id:reply-to:references: mime-version:in-reply-to; bh=UArt2EM4pE0fPWswCENdaTr2KP04kl+6xHjnd6dPVIs=; b=bRkCsGEuhPwialnHORR4X3qyqgJ2up5T531DoMKuMMU5Pu+nCmUd0UBe 9Of6GmaYkyHN9+IoLx61E2KVk6JKpLuq8qA7tKd8x2o6amTWLPTo37Ddg Jn74y9W2lTRyPEtEyILUo0ewJELuiqnTMTit0i33h4U/BDRokNTuKFtU+ vxhbzTpXCsWLov1fh8BgiUV9kPk3O09/kgEmSQXdIJwgl683mjPMx3Jhq NFgSifLYYs+XdeSY0sCYm8oftWIh9udtGO2odWWos/I9e6QlVNoUXdZMJ VbKI8jQK+Uj2av9mklTEtRepXPGPhocmhihSSTOMx233jvxiEeCPgksIv Q==; X-IronPort-AV: E=McAfee;i="6500,9779,10448"; a="319989074" X-IronPort-AV: E=Sophos;i="5.93,260,1654585200"; d="scan'208";a="319989074" Received: from orsmga007.jf.intel.com ([10.7.209.58]) by fmsmga101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 24 Aug 2022 03:32:41 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.93,260,1654585200"; d="scan'208";a="605987428" Received: from chaop.bj.intel.com (HELO localhost) ([10.240.193.75]) by orsmga007.jf.intel.com with ESMTP; 24 Aug 2022 03:32:31 -0700 Date: Wed, 24 Aug 2022 18:27:48 +0800 From: Chao Peng To: Matthew Wilcox Cc: Hugh Dickins , "Kirill A . Shutemov" , 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" , Jeff Layton , "J . Bruce Fields" , Andrew Morton , Shuah Khan , Mike Rapoport , Steven Price , "Maciej S . Szmigiero" , Vlastimil Babka , Vishal Annapurve , Yu Zhang , 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 , "Gupta, Pankaj" Subject: Re: [PATCH v7 00/14] KVM: mm: fd-based approach for supporting KVM guest private memory Message-ID: <20220824102748.GB1385482@chaop.bj.intel.com> Reply-To: Chao Peng References: <20220706082016.2603916-1-chao.p.peng@linux.intel.com> <20220818132421.6xmjqduempmxnnu2@box> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1661337163; h=from:from:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=ISTYoMJEnegimPADJUJ8nKLyr/LGctvkYBNWYy3jyL0=; b=ouhfDy0BV0fZ4hOCAl8tRjMWjLUwoKkI2XiNe3fMIfLbBTmCXOtlL3XRbl12OtqWiSwBxh QxU140jVn1Tn5cJqiyb+1dnY3b2WCr4M87mR0FQolg2m24PnZv9TfYPLSDDDFkxAfRTWnR TzunlQaedO9+mfVJczUfcIkvKYGEQYI= ARC-Authentication-Results: i=1; imf22.hostedemail.com; dkim=none ("invalid DKIM record") header.d=intel.com header.s=Intel header.b=bRkCsGEu; spf=none (imf22.hostedemail.com: domain of chao.p.peng@linux.intel.com has no SPF policy when checking 192.55.52.88) smtp.mailfrom=chao.p.peng@linux.intel.com; dmarc=fail reason="No valid SPF" header.from=intel.com (policy=none) ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1661337163; a=rsa-sha256; cv=none; b=rG6EQ70HgGzdmVK6mli8wZyPwqyiT9OIVUMojek9cmppTfqaH5byBSMixhOpMx11o0nf28 spNmbWJsqBEAm8l5f69S044Uo8CqlnPsYiL5NiibZPVtRyqlKqIMcauhyaBIxdOgCdF0BT iNiUW7Z45yF4o9gqLzlL9mwH7XYQmIw= Authentication-Results: imf22.hostedemail.com; dkim=none ("invalid DKIM record") header.d=intel.com header.s=Intel header.b=bRkCsGEu; spf=none (imf22.hostedemail.com: domain of chao.p.peng@linux.intel.com has no SPF policy when checking 192.55.52.88) smtp.mailfrom=chao.p.peng@linux.intel.com; dmarc=fail reason="No valid SPF" header.from=intel.com (policy=none) X-Rspam-User: X-Stat-Signature: uq434zob9xsg7mfm8163swhtb5sdw6z5 X-Rspamd-Queue-Id: 6B156C0037 X-Rspamd-Server: rspam10 X-HE-Tag: 1661337163-240510 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Sun, Aug 21, 2022 at 11:27:44AM +0100, Matthew Wilcox wrote: > On Thu, Aug 18, 2022 at 08:00:41PM -0700, Hugh Dickins wrote: > > tmpfs and hugetlbfs and page cache are designed around sharing memory: > > TDX is designed around absolutely not sharing memory; and the further > > uses which Sean foresees appear not to need it as page cache either. > > > > Except perhaps for page migration reasons. It's somewhat incidental, > > but of course page migration knows how to migrate page cache, so > > masquerading as page cache will give a short cut to page migration, > > when page migration becomes at all possible. > > I haven't read the patch series, and I'm not taking a position one way > or the other on whether this is better implemented as a shmem addition > or a shim that asks shmem for memory. Page migration can be done for > driver memory by using PageMovable. I just rewrote how it works, so > the details are top of my mind at the moment if anyone wants something > explained. Commit 68f2736a8583 is the key one to look at. Thanks Matthew. That is helpful to understand the current code. Chao