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 189F3C7EE2C for ; Mon, 15 May 2023 21:22:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S245484AbjEOVWX (ORCPT ); Mon, 15 May 2023 17:22:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49380 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S245488AbjEOVWS (ORCPT ); Mon, 15 May 2023 17:22:18 -0400 Received: from cavan.codon.org.uk (irc.codon.org.uk [IPv6:2a00:1098:84:22e::2]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6DDB9DDA7; Mon, 15 May 2023 14:22:08 -0700 (PDT) Received: by cavan.codon.org.uk (Postfix, from userid 1000) id AA4624252A; Mon, 15 May 2023 22:22:06 +0100 (BST) Date: Mon, 15 May 2023 22:22:06 +0100 From: Matthew Garrett To: "Daniel P. Smith" Cc: Ross Philipson , linux-kernel@vger.kernel.org, x86@kernel.org, linux-integrity@vger.kernel.org, linux-doc@vger.kernel.org, linux-crypto@vger.kernel.org, iommu@lists.linux-foundation.org, kexec@lists.infradead.org, linux-efi@vger.kernel.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, hpa@zytor.com, ardb@kernel.org, James.Bottomley@hansenpartnership.com, luto@amacapital.net, nivedita@alum.mit.edu, kanth.ghatraju@oracle.com, trenchboot-devel@googlegroups.com Subject: Re: [PATCH v6 04/14] x86: Secure Launch Resource Table header file Message-ID: <20230515212206.GA2162@srcf.ucam.org> References: <20230504145023.835096-1-ross.philipson@oracle.com> <20230504145023.835096-5-ross.philipson@oracle.com> <20230512105554.GB14461@srcf.ucam.org> <30d5891d-4747-8d67-2667-ff07628740bd@apertussolutions.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <30d5891d-4747-8d67-2667-ff07628740bd@apertussolutions.com> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-efi@vger.kernel.org On Mon, May 15, 2023 at 05:15:15PM -0400, Daniel P. Smith wrote: > On 5/12/23 06:55, Matthew Garrett wrote: > > On Thu, May 04, 2023 at 02:50:13PM +0000, Ross Philipson wrote: > > > > > +#define SLR_TABLE_MAGIC 0x4452544d > > > > From convention I'd expect this to be 0x534c5254, but not really an > > issue. > > Apologies, but which convention? Tables in ACPI and UEFI tend to have magic that corresponds to their name, so a table called SLRT would tend to have magic that matches the ASCII values for that. In this case the SLRT has DRTM as its magic, which is a touch unexpected. > > Oof. Having the kernel know about bootloaders has not worked out super > > well for us in the past. If someone writes a new bootloader, are they > > unable to Secure Launch any existing kernels? The pragmatic thing for > > them to do would be to just pretend they're grub, which kind of defeats > > the point of having this definition... > > Actually, this is not for making the kernel know about bootloaders. This is > dealing with the challenge created when the preamble was split for efi-stub, > and similar use cases, where what sets up the preamble, ie. the bootloader, > is separate from what invokes the dynamic launch, ie. the DLE handler. The > reality is that even in the simplest implementation of the DLE handler, a > remnant of GRUB for call back from efi-stub, there is information that is > needed to cross the gap. What if I don't use grub, but use something that behaves equivalently? Which value should be used here? > We wrote the TrenchBoot Secure Launch general spec [1] with as much > forethought as possible for the target environments. Specifically, the > desire is to have a common approach for x86 (Intel and AMD), Arm, and > perhaps down the road the POWER arch. In particular, I do not believe there > is anything in the Arm DRTM beta spec that prohibits a mixed 32/64 bit > environment. In the end it is better to for the spec to be safe for those > environments then having to make changes to the spec later down the road. Ok.