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=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 9FFECC64E7A for ; Tue, 1 Dec 2020 14:59:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5225F2084C for ; Tue, 1 Dec 2020 14:59:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391740AbgLAO7d (ORCPT ); Tue, 1 Dec 2020 09:59:33 -0500 Received: from foss.arm.com ([217.140.110.172]:44412 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389972AbgLAO7d (ORCPT ); Tue, 1 Dec 2020 09:59:33 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id A6CCA30E; Tue, 1 Dec 2020 06:58:47 -0800 (PST) Received: from C02TD0UTHF1T.local (unknown [10.57.30.155]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 444ED3F575; Tue, 1 Dec 2020 06:58:43 -0800 (PST) Date: Tue, 1 Dec 2020 14:58:40 +0000 From: Mark Rutland To: David Brazdil Cc: Sudeep Holla , kvmarm@lists.cs.columbia.edu, Jonathan Corbet , Catalin Marinas , Will Deacon , Marc Zyngier , James Morse , Julien Thierry , Suzuki K Poulose , Dennis Zhou , Tejun Heo , Christoph Lameter , Lorenzo Pieralisi , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kernel-team@android.com Subject: Re: [PATCH v3 06/23] kvm: arm64: Add kvm-arm.protected early kernel parameter Message-ID: <20201201145840.GC86881@C02TD0UTHF1T.local> References: <20201126155421.14901-1-dbrazdil@google.com> <20201126155421.14901-7-dbrazdil@google.com> <20201127163254.zxdrszlveaxhluwn@bogus> <20201201131913.u7m2eifvtus74dra@google.com> <20201201140734.GA86881@C02TD0UTHF1T.local> <20201201144349.bglz7yicc3peixe6@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201201144349.bglz7yicc3peixe6@google.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Dec 01, 2020 at 02:43:49PM +0000, David Brazdil wrote: > > > > be just me, but if you agree please update so that it doesn't give remote > > > > idea that it is not valid on VHE enabled hardware. > > > > > > > > I was trying to run this on the hardware and was trying to understand the > > > > details on how to do that. > > > > > > I see what you're saying, but !CONFIG_ARM64_VHE isn't accurate either. The > > > option makes sense if: > > > 1) all cores booted in EL2 > > > == is_hyp_mode_available() > > > 2) ID_AA64MMFR1_EL1.VH=0 or !CONFIG_ARM64_VHE > > > == !is_kernel_in_hyp_mode() > > > > > > The former feels implied for KVM, the latter could be 'Valid if the kernel > > > is running in EL1'? WDYT? > > > > I reckon we can avoid the restriction if we instead add an early stub > > like with have for KASLR. That way we could parse the command line > > early, and if necessary re-initialize EL2 and drop to EL1 before the > > main kernel has to make any decisions about how to initialize things. > > That would allow us to have a more general kvm-arm.mode option where a > > single kernel Image could support: > > > > * "protected" mode on nVHE or VHE HW > > * "nvhe" mode on nVHE or VHE HW > > * "vhe" mode on VHE HW > > > > ... defaulting to VHE/nVHE modes depending on HW support. > > > > That would also be somewhat future-proof if we have to add other > > variants of protected mode in future, as we could extend the mode option > > with parameters for each mode. > > Agreed that 'mode' is a more future-proof flag and I would very much love to > have an option to force nVHE on VHE HW. I however expect that the early stub > would not be a trivial addition and would not want to get into that in this > series. Could we agree on 'protected' as the only supported value for the time > being? Sure, that works for me. Thanks, Mark.