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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id A1C3EC79FAD for ; Wed, 9 Sep 2026 11:34:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=oSUP/FldKSKIh3rMEH+d3FwAjG9D+pH/7vnolvntLZ0=; b=uXW0w0LYzh0F4rPwWYSiqqVhFi ri3CNBHra0dv9lRpB6kxAfvpHDwVTAQDCcVK/cA47CUIaIuT0ghXQkhmp+BaMpnfQ5vsbITo9YdgZ 8P4M4uihoElsp9hFamMmxuGtJgxRdroMWyIU1SX93jetAP3q+UVJVw8oA9zbLagHMS0a3rG5bE61v ThbomWd//sWGhsovFEAx52KWKjF3GJzk8aiPS1gwln4AwlLQsD807mycsvTP8NDfO9841TVLM+/8K ao/jI4p31Hxnekbsoei0dznJLzRDyQe1Z8BiWl5Racxc2zBBBVyAfO9pjOp8/hDnirD0jV1oVTa/T LfPbomKQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1x4GZI-0000000Babx-2Vyc; Wed, 09 Sep 2026 11:34:20 +0000 Received: from tor.source.kernel.org ([2600:3c04:e001:324:0:1991:8:25]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1x4GZH-0000000Babe-0ZR0 for linux-arm-kernel@lists.infradead.org; Wed, 09 Sep 2026 11:34:19 +0000 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id 8010560207; Wed, 9 Sep 2026 11:34:18 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B3D401F00A3F; Wed, 9 Sep 2026 11:34:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788953658; bh=oSUP/FldKSKIh3rMEH+d3FwAjG9D+pH/7vnolvntLZ0=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=Yde7Jb30UcygvXK1+GjsPtdnydHn1R+M/nx8DmYk/Yf32NI2SN6NuUACHfnYM5AmP N+MpZQaEiEU1VY8D0fYerMGmJBbrnNH5FeTDmz5idDk18YK/FpLWJe60skjL4KHLvr PeEpzfV6ykd0BDY3jXAbCr+HK9My1i/y6y8Wrw4KrvpeLobGeL0VGZ+RIggo7CyqOP 1tTeQAZhegkLr9eFSXFKTSQiZV5QN+Er8GnUYkT+EnCQW0iQj6ytK9lzCj/BnwJlVR VylFoArNg/gAtvX6nhU4gSeUU43t0+01Kg2meWR8ZYhQkuGXr+BwlZDJBh2xPqi6sX knSUvbNG+XKNw== Date: Wed, 9 Sep 2026 12:34:11 +0100 From: "Lorenzo Stoakes (ARM)" To: Mark Brown Cc: Catalin Marinas , Will Deacon , Marc Zyngier , Joey Gouly , Suzuki K Poulose , Shuah Khan , Oliver Upton , Fuad Tabba , Peter Maydell , Leonardo Bras , Wei-Lin Chang , Yao Yuan , linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, kvmarm@lists.linux.dev, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v20 03/14] KVM: arm64: Manage GCS access and registers for guests Message-ID: References: <20260901-arm64-gcs-v20-0-f31750bdfadb@kernel.org> <20260901-arm64-gcs-v20-3-f31750bdfadb@kernel.org> <1effee02-41f0-4680-9a6f-9b9f12459ec1@sirena.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1effee02-41f0-4680-9a6f-9b9f12459ec1@sirena.org.uk> 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: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Mon, Sep 07, 2026 at 03:55:43PM +0100, Mark Brown wrote: > On Mon, Sep 07, 2026 at 03:14:34PM +0100, Lorenzo Stoakes (ARM) wrote: > > On Fri, Sep 04, 2026 at 10:07:49PM +0100, Mark Brown wrote: > > > On Fri, Sep 04, 2026 at 09:54:51AM +0100, Lorenzo Stoakes (ARM) wrote: > > > > I think the best thing overall would be to leave the runtime paths as > > > they are and refuse to run with an architecturally invalid setup, that > > > would avoid bloating the fast path. > > > Ack, it'd be nice to not have to worry about that. > > > Presumably we definitely want an oops on a GCS violation in general? > > Yes, the guest is going to want GCS exceptions delivering if they've > enabled them and something triggers them. It might also be relying on > the GCS for stack traces even if nothing triggers any GCS related fault. OK so the answer seems definitely to be disallowing the invalid config at runtime then I think! :) -- Cheers, Lorenzo