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=-15.5 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 31ED7C433B4 for ; Thu, 8 Apr 2021 11:00:09 +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 A8C20608FE for ; Thu, 8 Apr 2021 11:00:08 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A8C20608FE 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: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=Z3p1J6F34VeK5b2yI8X352ewF02casOvG/mZKkRUJWI=; b=G8NTO/GbCnKf52Z3CuW6PK+ZB 1MJGv4NJjJir4X+S+vnBF6J+KHdNs1iNdgk2S7aj0zJGGa2movw3tdpPF9kAr7Fz5sgEVRuYIyjxJ CF/jdtcZBMdy5unMWLmbniDtTMfISAXj2uoVsBXpOlc2PkQGkJPY4wvHvOG87nnqKu+jE+ReODX8b TL6H9FjtqZABBf6Pa0V70WwanGWhVsSYi6QF5R/jlbHfjurDEsOZ2GZTXuSbHzhjls3qPmvlpt+L8 cYxnN4/sffUQ4Cf+RalgZ4ksGmEgFP+eFvSrTqsFmlwe/TP2BxPjfHky5WYrGdZjGcqF+JWktQzmO NNlqexJWg==; Received: from localhost ([::1] helo=desiato.infradead.org) by desiato.infradead.org with esmtp (Exim 4.94 #2 (Red Hat Linux)) id 1lUSMs-007ioz-9c; Thu, 08 Apr 2021 10:58:34 +0000 Received: from mail.kernel.org ([198.145.29.99]) by desiato.infradead.org with esmtps (Exim 4.94 #2 (Red Hat Linux)) id 1lUSMo-007io8-3V for linux-arm-kernel@lists.infradead.org; Thu, 08 Apr 2021 10:58:31 +0000 Received: by mail.kernel.org (Postfix) with ESMTPSA id 5A669608FE; Thu, 8 Apr 2021 10:58:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1617879508; bh=c2s8NWJIXr2pIuPd0v9uyxUJSdXpvOv/oUlgecep2Sc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=LJ0x/JbDPGowwjsb8khMS8pcKT7NT+K4lGF54UV0k6hfmendRnsRJf0Q7pdThEu8G Sjras/DbUxPygJOpIu/yfCzKReEXojb0P/VpCcUsvN/R6ttprm79hjDjioFPWFO6uE DzBEfV30R5lKQ7DF6jNQ4o7YFrF8iaJJLywcLW8esMP7Y8jnqa6zMWxKT19zAaNkIa tuTnAgg+qaLlr+HP0yVJ7+ietUfK3xNBs6SKFuON7gWB0F15GE5Caifg7qGvjFJzil xeXpa8PiIg6lUOlZSPZWo0oWk3KaH0mXETc6gcTihbEjWSJeNHumEdAKfGe1kgbTBc 2GtfeGsqeDcXQ== Date: Thu, 8 Apr 2021 11:58:23 +0100 From: Will Deacon To: Marc Zyngier 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 Message-ID: <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> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <8474e539259346842178f51a26d59d74@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-20210408_115830_358916_DB766D1D X-CRM114-Status: GOOD ( 26.35 ) 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, 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! > 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. Will _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel