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=-14.0 required=3.0 tests=BAYES_00,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,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 8E213C47084 for ; Tue, 25 May 2021 17:14:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 705656141D for ; Tue, 25 May 2021 17:14:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233581AbhEYRPd (ORCPT ); Tue, 25 May 2021 13:15:33 -0400 Received: from mail.kernel.org ([198.145.29.99]:54094 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233371AbhEYRPb (ORCPT ); Tue, 25 May 2021 13:15:31 -0400 Received: from disco-boy.misterjones.org (disco-boy.misterjones.org [51.254.78.96]) (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 9D21D61417; Tue, 25 May 2021 17:14:01 +0000 (UTC) Received: from 78.163-31-62.static.virginmediabusiness.co.uk ([62.31.163.78] helo=why.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1llacx-003Wo9-Fm; Tue, 25 May 2021 18:13:59 +0100 Date: Tue, 25 May 2021 18:13:58 +0100 Message-ID: <877djmwxbd.wl-maz@kernel.org> From: Marc Zyngier To: Will Deacon Cc: linux-arm-kernel@lists.infradead.org, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, Catalin Marinas , Greg Kroah-Hartman , Peter Zijlstra , Morten Rasmussen , Qais Yousef , Suren Baghdasaryan , Quentin Perret , Tejun Heo , Johannes Weiner , Ingo Molnar , Juri Lelli , Vincent Guittot , "Rafael J. Wysocki" , Dietmar Eggemann , Daniel Bristot de Oliveira , kernel-team@android.com Subject: Re: [PATCH v7 22/22] Documentation: arm64: describe asymmetric 32-bit support In-Reply-To: <20210525151432.16875-23-will@kernel.org> References: <20210525151432.16875-1-will@kernel.org> <20210525151432.16875-23-will@kernel.org> 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: 62.31.163.78 X-SA-Exim-Rcpt-To: will@kernel.org, linux-arm-kernel@lists.infradead.org, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, catalin.marinas@arm.com, gregkh@linuxfoundation.org, peterz@infradead.org, morten.rasmussen@arm.com, qais.yousef@arm.com, surenb@google.com, qperret@google.com, tj@kernel.org, hannes@cmpxchg.org, mingo@redhat.com, juri.lelli@redhat.com, vincent.guittot@linaro.org, rjw@rjwysocki.net, dietmar.eggemann@arm.com, bristot@redhat.com, kernel-team@android.com 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: linux-kernel@vger.kernel.org On Tue, 25 May 2021 16:14:32 +0100, Will Deacon wrote: > > Document support for running 32-bit tasks on asymmetric 32-bit systems > and its impact on the user ABI when enabled. > > Signed-off-by: Will Deacon > --- > .../admin-guide/kernel-parameters.txt | 3 + > Documentation/arm64/asymmetric-32bit.rst | 154 ++++++++++++++++++ > Documentation/arm64/index.rst | 1 + > 3 files changed, 158 insertions(+) > create mode 100644 Documentation/arm64/asymmetric-32bit.rst > [...] > +KVM > +--- > + > +Although KVM will not advertise 32-bit EL0 support to any vCPUs on an > +asymmetric system, a broken guest at EL1 could still attempt to execute > +32-bit code at EL0. In this case, an exit from a vCPU thread in 32-bit > +mode will return to host userspace with an ``exit_reason`` of > +``KVM_EXIT_FAIL_ENTRY``. Nit: there is a bit more to it. The vcpu will be left in a permanent non-runnable state until KVM_ARM_VCPU_INIT is issued to reset the vcpu into a saner state. Thanks, M. -- Without deviation from the norm, progress is not possible. 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=-14.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 1AD08C2B9F8 for ; Tue, 25 May 2021 17:17:02 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id D60ED613F5 for ; Tue, 25 May 2021 17:17:01 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D60ED613F5 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Subject:Cc:To:From:Message-ID:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=c7Dl+gAHY9qy5sn76BqNZ6bRjFPbuzs1vp1bbrgxRw4=; b=xu98+haTyNwl3j zgalKNmPN9SwqhdKJF7NsEpzh8X+vw3RmLAsvfZFdVt1YZZLcpZZJVTpz8Xd3fBqvl8MonxWMkh7p VZ1ppLNmsD6S1MiAqksRcAZoatbqfr9l6fvn9Gi92Qs9S8kpD+xYTbY4yTbVBFjIKQMOsHvr1NlMX InvfYvPEJ61zT1et9lWiGEsFgylcZadktLkRQ2JvSURWHyw6LnU7jlD4dTAdUFLkMlrEF0BcR3CAP T5vQstv5bmKP6zNFfpIliehqJuoj4G8If0VzHwrN9r9mIymsiaMcmsREJMrYzTnfETcK+DeQ20yC6 tRa+2aSDjSlqLdhiTViQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1llad7-006lcC-44; Tue, 25 May 2021 17:14:10 +0000 Received: from mail.kernel.org ([198.145.29.99]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1llad0-006lZq-34 for linux-arm-kernel@lists.infradead.org; Tue, 25 May 2021 17:14:03 +0000 Received: from disco-boy.misterjones.org (disco-boy.misterjones.org [51.254.78.96]) (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 9D21D61417; Tue, 25 May 2021 17:14:01 +0000 (UTC) Received: from 78.163-31-62.static.virginmediabusiness.co.uk ([62.31.163.78] helo=why.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1llacx-003Wo9-Fm; Tue, 25 May 2021 18:13:59 +0100 Date: Tue, 25 May 2021 18:13:58 +0100 Message-ID: <877djmwxbd.wl-maz@kernel.org> From: Marc Zyngier To: Will Deacon Cc: linux-arm-kernel@lists.infradead.org, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, Catalin Marinas , Greg Kroah-Hartman , Peter Zijlstra , Morten Rasmussen , Qais Yousef , Suren Baghdasaryan , Quentin Perret , Tejun Heo , Johannes Weiner , Ingo Molnar , Juri Lelli , Vincent Guittot , "Rafael J. Wysocki" , Dietmar Eggemann , Daniel Bristot de Oliveira , kernel-team@android.com Subject: Re: [PATCH v7 22/22] Documentation: arm64: describe asymmetric 32-bit support In-Reply-To: <20210525151432.16875-23-will@kernel.org> References: <20210525151432.16875-1-will@kernel.org> <20210525151432.16875-23-will@kernel.org> 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") X-SA-Exim-Connect-IP: 62.31.163.78 X-SA-Exim-Rcpt-To: will@kernel.org, linux-arm-kernel@lists.infradead.org, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, catalin.marinas@arm.com, gregkh@linuxfoundation.org, peterz@infradead.org, morten.rasmussen@arm.com, qais.yousef@arm.com, surenb@google.com, qperret@google.com, tj@kernel.org, hannes@cmpxchg.org, mingo@redhat.com, juri.lelli@redhat.com, vincent.guittot@linaro.org, rjw@rjwysocki.net, dietmar.eggemann@arm.com, bristot@redhat.com, kernel-team@android.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210525_101402_196314_ECD19D29 X-CRM114-Status: GOOD ( 21.06 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, 25 May 2021 16:14:32 +0100, Will Deacon wrote: > > Document support for running 32-bit tasks on asymmetric 32-bit systems > and its impact on the user ABI when enabled. > > Signed-off-by: Will Deacon > --- > .../admin-guide/kernel-parameters.txt | 3 + > Documentation/arm64/asymmetric-32bit.rst | 154 ++++++++++++++++++ > Documentation/arm64/index.rst | 1 + > 3 files changed, 158 insertions(+) > create mode 100644 Documentation/arm64/asymmetric-32bit.rst > [...] > +KVM > +--- > + > +Although KVM will not advertise 32-bit EL0 support to any vCPUs on an > +asymmetric system, a broken guest at EL1 could still attempt to execute > +32-bit code at EL0. In this case, an exit from a vCPU thread in 32-bit > +mode will return to host userspace with an ``exit_reason`` of > +``KVM_EXIT_FAIL_ENTRY``. Nit: there is a bit more to it. The vcpu will be left in a permanent non-runnable state until KVM_ARM_VCPU_INIT is issued to reset the vcpu into a saner state. Thanks, M. -- Without deviation from the norm, progress is not possible. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel