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 2ED52C2BB41 for ; Wed, 17 Aug 2022 10:07:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235764AbiHQKHS (ORCPT ); Wed, 17 Aug 2022 06:07:18 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43368 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229764AbiHQKHO (ORCPT ); Wed, 17 Aug 2022 06:07:14 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A36685EDCC for ; Wed, 17 Aug 2022 03:07:13 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 3E37D61458 for ; Wed, 17 Aug 2022 10:07:13 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 93BD3C433D6; Wed, 17 Aug 2022 10:07:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1660730832; bh=Trzx1RKPpCk+PY9PWVhC3SaQLll2gZJqQPhYEYtpBs4=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=Wt9OmIxeM/7jTZJGYmd6EKT20NKldj6lr6pGrGbTkvBgsR3LS3b/E3xVRgnXsl8U9 HgP6eW+iQrOiQa7S7c0HLKQGMK2VncfU3gAwnI3jcqzboUFXxm01a36tkO2UkMKmr0 J9OtpTk8lwXamC//D/xcwyGYH0TARpUnrDU5kbaFsb8AkUC6M3SIg0/sZs51OMkSos JxU8m0mO20yU76RtoODr7I90pf6G38MSRUY9HaKOqnLogOo/heIQLqWQUhAtD6Opig PgTf0TuUY6Ty3BKhvaU0j930MXvAE0ZJYxvEq9js1w7Gz2HGdnI4J4Edv2e7ZDAfet rD9WK6urfA/Hg== Received: from sofa.misterjones.org ([185.219.108.64] helo=why.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.95) (envelope-from ) id 1oOFx8-003hbm-CE; Wed, 17 Aug 2022 11:07:10 +0100 Date: Wed, 17 Aug 2022 11:07:10 +0100 Message-ID: <87tu6bw5dd.wl-maz@kernel.org> From: Marc Zyngier To: Oliver Upton Cc: kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, james.morse@arm.com, alexandru.elisei@arm.com, suzuki.poulose@arm.com, will@kernel.org Subject: Re: [PATCH v2 0/2] KVM: arm64: Uphold 64bit-only behavior on asymmetric systems In-Reply-To: <20220816192554.1455559-1-oliver.upton@linux.dev> References: <20220816192554.1455559-1-oliver.upton@linux.dev> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/27.1 (x86_64-pc-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=US-ASCII X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: oliver.upton@linux.dev, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, james.morse@arm.com, alexandru.elisei@arm.com, suzuki.poulose@arm.com, will@kernel.org X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Tue, 16 Aug 2022 20:25:52 +0100, Oliver Upton wrote: > > Small series to fix a couple issues around when 64bit-only behavior is > applied. As KVM is more restrictive than the kernel in terms of 32bit > support (no asymmetry), we really needed our own predicate when the > meaning of system_supports_32bit_el0() changed in commit 2122a833316f > ("arm64: Allow mismatched 32-bit EL0 support"). > > Lightly tested as I do not have any asymmetric systems on hand at the > moment. Attention on patch 2 would be appreciated as it affects ABI. I don't think this significantly affect the ABI, as it is pretty unlikely that you'd have been able to execute the result, at least on VM creation (set PSTATE.M=USR, start executing, get the page fault on the first instruction... bang). You could have tricked it in other ways, but at the end of the day you're running a broken hypervisor on an even more broken system... Anyway, I've applied this to fixes. Thanks, M. -- Without deviation from the norm, progress is not possible.