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=-17.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 EAD69C2B9F8 for ; Tue, 25 May 2021 17:27:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CF4C961059 for ; Tue, 25 May 2021 17:27:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234012AbhEYR2p (ORCPT ); Tue, 25 May 2021 13:28:45 -0400 Received: from mail.kernel.org ([198.145.29.99]:57492 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231968AbhEYR2k (ORCPT ); Tue, 25 May 2021 13:28:40 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id EB5A061059; Tue, 25 May 2021 17:27:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1621963630; bh=Py8o9CpBdeHqkrPglGRVHtpKGSFKgoBf9UwTlNommvg=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=SlJVOP5HjP6X7p8+sAHbrLWIDwGzcdXySE+klKG1rX1/eGWcXcx6JZBK91dIkPD9c kX99nnqLMCzVeNrxkUWho5UAKkHMdpUFanZeWK0PoKDXZZlTKKB1ctei7V3AO2lkSl gqfPRbxSeEeWxTjimVy1kemYb/Ds5GuWfgl7ZZDG0ibTdlhhJcu3d/kVKbq4ce1fyQ K8gYNZA6Uc3jUNc5Yp0ftZsLy8CWhELiFQFL6Qt6+soa0gjTgryne4cauQmxRfCwlo /1Jo9dGP+HLN5A1uJWMtUcR8okTTNkEBaQCzPFnAJtPTfmtVKb2O1J5ygtlrcWBxWi /T3ezz3tcdrmw== Date: Tue, 25 May 2021 18:27:03 +0100 From: Will Deacon To: Marc Zyngier 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 Message-ID: <20210525172703.GA17250@willie-the-truck> References: <20210525151432.16875-1-will@kernel.org> <20210525151432.16875-23-will@kernel.org> <877djmwxbd.wl-maz@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <877djmwxbd.wl-maz@kernel.org> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, May 25, 2021 at 06:13:58PM +0100, Marc Zyngier wrote: > 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, I'll add "and will remain non-runnable until re-initialised by a subsequent KVM_ARM_VCPU_INIT operation". Can the VMM tell that it needs to do that? I wonder if we should be setting 'hardware_entry_failure_reason' to distinguish this case. Will 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=-15.9 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,USER_AGENT_SANE_1 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 0A239C2B9F8 for ; Tue, 25 May 2021 17:31:28 +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 C30AF61059 for ; Tue, 25 May 2021 17:31:27 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C30AF61059 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:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=pPgvknfEpiE3AJR2PHWXNyz02+ZZOHVIGkUoR8j1BYE=; b=F66HHb4dpLphv8 od7hTBBDCf+BQgW/4XWdmX6ojf+N5UsMfVcoVCJ437UkNggAIuLXm8LqwtZcGcYXH8aXow8SepYvO aTXHUmTCuYWLlDpJ0TV5dAjCg+N5QBbDTYf/kv5aP6nWK4qJP6YVFmCE0CvW6NOdPUUg1xazC+gKm olMZEr0BfOCRPqiojoKw2KRJSwZ3ZoieSyTY8LHID3rCkweKXRj7WIiUR1Mb1l5/RNEm0y7qvrqog 3aNs+8d+yDddgDQ/VBh9/DlSxcNYJehNlTYSe+WPwiHhI87oBPiPn8tST/xiCj2RcrzKBefgbWVWK N/KhRNfLcg15wGf0Um7g==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1llasG-006soZ-DB; Tue, 25 May 2021 17:29:48 +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 1llapi-006rTQ-Ii for linux-arm-kernel@lists.infradead.org; Tue, 25 May 2021 17:27:12 +0000 Received: by mail.kernel.org (Postfix) with ESMTPSA id EB5A061059; Tue, 25 May 2021 17:27:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1621963630; bh=Py8o9CpBdeHqkrPglGRVHtpKGSFKgoBf9UwTlNommvg=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=SlJVOP5HjP6X7p8+sAHbrLWIDwGzcdXySE+klKG1rX1/eGWcXcx6JZBK91dIkPD9c kX99nnqLMCzVeNrxkUWho5UAKkHMdpUFanZeWK0PoKDXZZlTKKB1ctei7V3AO2lkSl gqfPRbxSeEeWxTjimVy1kemYb/Ds5GuWfgl7ZZDG0ibTdlhhJcu3d/kVKbq4ce1fyQ K8gYNZA6Uc3jUNc5Yp0ftZsLy8CWhELiFQFL6Qt6+soa0gjTgryne4cauQmxRfCwlo /1Jo9dGP+HLN5A1uJWMtUcR8okTTNkEBaQCzPFnAJtPTfmtVKb2O1J5ygtlrcWBxWi /T3ezz3tcdrmw== Date: Tue, 25 May 2021 18:27:03 +0100 From: Will Deacon To: Marc Zyngier 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 Message-ID: <20210525172703.GA17250@willie-the-truck> References: <20210525151432.16875-1-will@kernel.org> <20210525151432.16875-23-will@kernel.org> <877djmwxbd.wl-maz@kernel.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <877djmwxbd.wl-maz@kernel.org> User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210525_102710_713141_B743B89A X-CRM114-Status: GOOD ( 19.98 ) 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, May 25, 2021 at 06:13:58PM +0100, Marc Zyngier wrote: > 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, I'll add "and will remain non-runnable until re-initialised by a subsequent KVM_ARM_VCPU_INIT operation". Can the VMM tell that it needs to do that? I wonder if we should be setting 'hardware_entry_failure_reason' to distinguish this case. Will _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel