From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 842C9545288; Wed, 9 Sep 2026 11:34:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788953660; cv=none; b=Dp7xJLJxi4LsdZgkbGzgwJb7o4ovMShZK9oWlYp5vT9A6HXiEsI7bscnt92nz4InoVKqVPJG9hBWYPyB/QmNoxHKoCfR7dg9uve/uRDG3Gy8wpzLKpvDZXRwgEll6cWxB5WICBBmieamI61OVErBP+jg3AasPGwDDn1ttxWM1zQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788953660; c=relaxed/simple; bh=BYY1z10WkjEwK2mb4dVa2Dd8xSUo3dhWo++giVKDhnw=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=o5STOVcNODuqPBvOd+Jc4+ysLUEjcyP8ueGnLFp1wdM9deie4hkRtHPeJQly8nZigLpe8dWttXQd/4OmyVbLfX2JekVaxkTAFAPtowZSnudCI4C+hNEdy0/WDwefQ6yhSahzfw21ozUVdyJHYKTwvp2l2J6ExH/xb7sopRnnTTY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Yde7Jb30; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Yde7Jb30" 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> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: 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> 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