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=-6.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 850E6C2D0EF for ; Fri, 17 Apr 2020 12:50:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5D84E208E4 for ; Fri, 17 Apr 2020 12:50:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1587127812; bh=1Kssa3G/QCo5jRCKyBkgrgk7TiSh1kwDD4fBjcBMC70=; h=Date:From:To:Cc:Subject:In-Reply-To:References:List-ID:From; b=pxAE1xx6TJM2DdphtFTbXuqi1STfqVeB2eUWW62LqEenRUU/3f5ZU6UQCAAvAJwyF pYkWbsPxtNmtddqZpwqf9LzIjSNGdx2X8HA5ERcfxHhx3rXNsSit2gM+YoVTb6lCbi d3YQM/0q4kKjnk3V3aKkxSRIdY3/fVeLZgDEKHcU= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729841AbgDQMuI (ORCPT ); Fri, 17 Apr 2020 08:50:08 -0400 Received: from mail.kernel.org ([198.145.29.99]:39132 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727877AbgDQMuH (ORCPT ); Fri, 17 Apr 2020 08:50:07 -0400 Received: from devnote2 (NE2965lan1.rev.em-net.ne.jp [210.141.244.193]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id E52042083E; Fri, 17 Apr 2020 12:50:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1587127806; bh=1Kssa3G/QCo5jRCKyBkgrgk7TiSh1kwDD4fBjcBMC70=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=2SHu1HjYaq+TUUvOFDh4rRrPGE6erjABlIPm/oYjVffmYc3Po6EJLX6WpPqoJLKFB x8U/cj4n5jria1Y1NHVeXCy8i714yrYSGRhb/Pctx6gILbNZMLN0L6RoLRqN3y4kR3 cY2VKGNJFQZzlfQ6mXT+bDZNQlh5C3ufeAzFZ6ZM= Date: Fri, 17 Apr 2020 21:50:00 +0900 From: Masami Hiramatsu To: Joerg Roedel Cc: Borislav Petkov , Joerg Roedel , x86@kernel.org, hpa@zytor.com, Andy Lutomirski , Dave Hansen , Peter Zijlstra , Thomas Hellstrom , Jiri Slaby , Dan Williams , Tom Lendacky , Juergen Gross , Kees Cook , linux-kernel@vger.kernel.org, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org Subject: Re: [PATCH 05/70] x86/insn: Make inat-tables.c suitable for pre-decompression code Message-Id: <20200417215000.47141001f80005f41153d22e@kernel.org> In-Reply-To: <20200416152406.GB4290@8bytes.org> References: <20200319091407.1481-1-joro@8bytes.org> <20200319091407.1481-6-joro@8bytes.org> <20200325153945.GD27261@zn.tnic> <20200327120232.c8e455ca100dc0d96e4ddc43@kernel.org> <20200416152406.GB4290@8bytes.org> X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.32; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Thu, 16 Apr 2020 17:24:06 +0200 Joerg Roedel wrote: > Hi Masami, > > On Fri, Mar 27, 2020 at 12:02:32PM +0900, Masami Hiramatsu wrote: > > On Wed, 25 Mar 2020 16:39:45 +0100 > > Borislav Petkov wrote: > > > > > + Masami. > > > > > > On Thu, Mar 19, 2020 at 10:13:02AM +0100, Joerg Roedel wrote: > > > > From: Joerg Roedel > > > > > > > > The inat-tables.c file has some arrays in it that contain pointers to > > > > other arrays. These pointers need to be relocated when the kernel > > > > image is moved to a different location. > > > > > > > > The pre-decompression boot-code has no support for applying ELF > > > > relocations, so initialize these arrays at runtime in the > > > > pre-decompression code to make sure all pointers are correctly > > > > initialized. > > > > I need to check the whole series, but as far as I can understand from > > this patch, this seems not allowing to store the address value in > > static pointers. It may break more things, for example _kprobe_blacklist > > records the NOKPROBE_SYMBOL() symbol addresses at the build time. > > The runtime-initialization function is only used in the > pre-decompression boot code (arch/x86/boot/compressed/) which is not > part of the running kernel image. At that stage of booting there is no > support for kprobe or tracing or any other neat features that might > break things here. Ah, I got it. So you intended to port the instruction decoder to pre-decompression boot code, correct? > > > > + print "#ifndef __BOOT_COMPRESSED\n" > > > > + > > > > # print escape opcode map's array > > > > print "/* Escape opcode map array */" > > > > print "const insn_attr_t * const inat_escape_tables[INAT_ESC_MAX + 1]" \ > > > > @@ -388,6 +391,51 @@ END { > > > > for (j = 0; j < max_lprefix; j++) > > > > if (atable[i,j]) > > > > print " ["i"]["j"] = "atable[i,j]"," > > > > - print "};" > > > > + print "};\n" > > > > + > > > > + print "#else /* !__BOOT_COMPRESSED */\n" > > > > I think the definitions of inat_*_tables can be shared in both case. > > If __BOOT_COMPRESSED is set, we can define inat_init_tables() as a > > initialize function, and if not, it will be just a dummy "do {} while (0)". > > The inat_*_tables are all declared const, so this way it is not possible > to change them at runtime. Indeed. > For the running kernel image this is fine, as > there are ELF relocations which fix things up, but at the > pre-decompression boot stage there are no ELF relocations which can fix > the tables, so the pointers in there need to be initialized at runtime. OK. > > > BTW, where is the __BOOT_COMPRESSED defined? > > It is defined in arch/x86/boot/compressed/sev-es.c by patch > > x86/boot/compressed/64: Setup GHCB Based VC Exception handler > > which also includes parts of the instruction decoder into the > pre-decompression boot code and adds the only call-site for > inat_init_tables(). Thanks, I understand it. > > > > > + print "static void inat_init_tables(void)" > > > > This functions should be "inline". > > And I can not see the call-site of inat_init_tables() in this patch. > > The call-site is added with the patch that includes the > instruction decoder into the pre-decompression code. If possible I'd > like to keep those things separate, as both patches are already pretty > big by themselfes (and they do different things, in different parts of > the code). OK, if you will send v2, please CC both to me. > > > If possible, please include call-site with definition (especially > > new init function) so that I can check the init call timing too. > > The function is called at the first #VC exception after a GHCB has been > set up. Call-path is: boot_vc_handler -> sev_es_setup_ghcb -> > inat_init_tables. sound good to me. Thank you, > > See > > https://git.kernel.org/pub/scm/linux/kernel/git/joro/linux.git/tree/arch/x86/boot/compressed/sev-es.c?h=sev-es-client-v5.6-rc6 > > for the full code there. > > Thanks, > > Joerg -- Masami Hiramatsu