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,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 AF253C433B4 for ; Thu, 8 Apr 2021 13:07:53 +0000 (UTC) Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) (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 386406113B for ; Thu, 8 Apr 2021 13:07:53 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 386406113B 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=desiato.20200630; 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=PJLlORZrU9RzUyhnAHACahQZQh6V+mbzbQHV/KA8HVw=; b=eAyvg8IDDEi24reyRIER0codM QVsGEyAeTC+nTTlPhgXnRu+jYTzL/u3j8xbvYwhNb46XkhG/5/tMxRIZGSYPEhq3B1WNN5bYDZoJS YhhbZZDswROla5n6syksBNoKgn6vfwOdKs0gA21CPm9Y2kMneUJgpiFok+R5/tIt5E7R17uzD0KQr DjxbGS2/en5oAD2zaspyxb6AIZClsOcBulUjBDo16ROrUW4RbCNPH63NQuXfOopj5+0GIuQ7oyytI zn81ife07GexfF7tTRfdYWgum+7cQ/wjzrK+6SfwIJnMMtj5Wa1Z5wfupizBJ8p/om1TapaFee8uQ b6Etm5zjQ==; Received: from localhost ([::1] helo=desiato.infradead.org) by desiato.infradead.org with esmtp (Exim 4.94 #2 (Red Hat Linux)) id 1lUUMN-0084KJ-IB; Thu, 08 Apr 2021 13:06:11 +0000 Received: from mail.kernel.org ([198.145.29.99]) by desiato.infradead.org with esmtps (Exim 4.94 #2 (Red Hat Linux)) id 1lUUMF-0084Jk-5a for linux-arm-kernel@lists.infradead.org; Thu, 08 Apr 2021 13:06:05 +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 7CB4D6113B; Thu, 8 Apr 2021 13:05:58 +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) (envelope-from ) id 1lUUM8-006JIY-Cq; Thu, 08 Apr 2021 14:05:56 +0100 Date: Thu, 08 Apr 2021 14:05:55 +0100 Message-ID: <8735w1orik.wl-maz@kernel.org> From: Marc Zyngier To: Will Deacon Cc: linux-arm-kernel@lists.infradead.org, Hector Martin , Arnd Bergmann , Mark Rutland , Catalin Marinas , kernel-team@android.com Subject: Re: [PATCH v2 3/3] arm64: Allow nVHE impaired CPUs to boot without CONFIG_ARM64_VHE In-Reply-To: <20210408105823.GB17280@willie-the-truck> References: <20210330173947.999859-1-maz@kernel.org> <20210330173947.999859-4-maz@kernel.org> <20210407211848.GE16198@willie-the-truck> <8474e539259346842178f51a26d59d74@kernel.org> <20210408105823.GB17280@willie-the-truck> 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, marcan@marcan.st, arnd@kernel.org, mark.rutland@arm.com, catalin.marinas@arm.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-20210408_140603_635799_A5F5D296 X-CRM114-Status: GOOD ( 36.69 ) 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 Thu, 08 Apr 2021 11:58:23 +0100, Will Deacon wrote: > > On Thu, Apr 08, 2021 at 11:31:42AM +0100, Marc Zyngier wrote: > > On 2021-04-07 22:18, Will Deacon wrote: > > > On Tue, Mar 30, 2021 at 06:39:47PM +0100, Marc Zyngier wrote: > > > > CPUs stuck in VHE mode need some additional care if the kernel > > > > is compiled without CONFIG_ARM64_VHE. > > > > > > > > Treat this case as another version of a mismatched boot, and > > > > prevent KVM from being initialised. The machine will boot in > > > > some bizarre state, using TPIDR_EL1 instead of TPIDR_EL2, but > > > > otherwise be functional. > > > > > > > > Signed-off-by: Marc Zyngier > > > > --- > > > > arch/arm64/include/asm/virt.h | 18 +++++++++++++----- > > > > arch/arm64/kvm/va_layout.c | 9 +++++++++ > > > > 2 files changed, 22 insertions(+), 5 deletions(-) > > > > > > Hmm, I think we definitely need _something_ here, but it's a bit > > > annoying > > > to put ourselves into this weird state just for the sake of one stupid > > > machine. > > > > Which is why I'm not keen at all on this patch, and I'm happy to see > > the machine die a painful death. We really can't be blamed for terminally > > buggy HW, which the M1 obviously is. > > Perhaps, but it's not clear at all how the problem manifests and so we > _will_ be blamed when things go wonky, especially as the real culprits > all seem to be hiding... > > > > What if we dropped CONFIG_ARM64_VHE and made the VHE code unconditional > > > instead? Is there a good reason to allow it to be disabled nowadays? > > > > What do we do for the other camp, aka people really wanting to run nVHE > > without any command line parameter? I can't see why you'd want to do > > that, but hey, that's only me. > > They can pass the command-line parameter, no? If we ever get CMDLINE_EXTEND > support back, they could even add it in there! My point was that they could do it *without* the parameter. No skin off my nose anyway. > > > I'd be quite happy to see CONFIG_ARM64_VHE go though. Let me know if you > > want a patch doing that instead. > > Yes please. Right, let me repost the series then. 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