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 X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 21CFFC5CFC0 for ; Mon, 18 Jun 2018 13:33:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D27A020850 for ; Mon, 18 Jun 2018 13:33:17 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D27A020850 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934438AbeFRNdQ (ORCPT ); Mon, 18 Jun 2018 09:33:16 -0400 Received: from mga09.intel.com ([134.134.136.24]:5448 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933585AbeFRNdP (ORCPT ); Mon, 18 Jun 2018 09:33:15 -0400 X-Amp-Result: UNSCANNABLE X-Amp-File-Uploaded: False Received: from orsmga003.jf.intel.com ([10.7.209.27]) by orsmga102.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 18 Jun 2018 06:33:14 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.51,239,1526367600"; d="scan'208";a="60125222" Received: from black.fi.intel.com ([10.237.72.28]) by orsmga003.jf.intel.com with ESMTP; 18 Jun 2018 06:33:11 -0700 Received: by black.fi.intel.com (Postfix, from userid 1000) id CE679FA; Mon, 18 Jun 2018 16:33:12 +0300 (EEST) Date: Mon, 18 Jun 2018 16:33:12 +0300 From: "Kirill A. Shutemov" To: Dave Hansen Cc: Ingo Molnar , x86@kernel.org, Thomas Gleixner , "H. Peter Anvin" , Tom Lendacky , Kai Huang , Jacob Pan , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCHv3 15/17] x86/mm: Implement sync_direct_mapping() Message-ID: <20180618133312.kb6j25jvf6dr7dvh@black.fi.intel.com> References: <20180612143915.68065-1-kirill.shutemov@linux.intel.com> <20180612143915.68065-16-kirill.shutemov@linux.intel.com> <41c9db7f-2277-4403-5556-df56b686d5c8@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <41c9db7f-2277-4403-5556-df56b686d5c8@intel.com> User-Agent: NeoMutt/20170714-126-deb55f (1.8.3) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jun 13, 2018 at 06:41:21PM +0000, Dave Hansen wrote: > On 06/12/2018 07:39 AM, Kirill A. Shutemov wrote: > > arch/x86/include/asm/mktme.h | 6 + > > arch/x86/mm/init_64.c | 6 + > > arch/x86/mm/mktme.c | 444 +++++++++++++++++++++++++++++++++++ > > 3 files changed, 456 insertions(+) > > Can we not do any better than 400 lines of new open-coded pagetable > hacking? It's not pretty, but I don't see much options. I first tried to modify routines that initialize/modify/remove parts of direct mapping to keep all per-KeyID direct mappings in sync from start. But it didn't really fly. We need to initialize direct mapping very early when we don't have a way to allocated page in a usual way. We have very limited pool of pre-allocated pages to allocate page tables from and it's not able to satisfy demand for multiple direct mappings. So I had to go with syncing it later on. When we have working page allocator. Regarding open-codeness, we need to walk two subtrees in lock steps. I don't see how get mm/pagewalk.c to work in such use case. (And I don't really like callback-based pagewalker.) -- Kirill A. Shutemov