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 850CD42D757; Fri, 4 Sep 2026 13:21:01 +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=1788528065; cv=none; b=Aq7zTDe6o1+zKv7L6lwSQsI0lD4rMmU9wKBDnmTHwM7TI3eEJJ11WPzIEtW8OzOOKBwW5cbm7gHb6Y5CXhnuWK1EMfNiQTqSLBTFhYwUnZ0Z65ULwmATj5yKXOO6Lkw/3j/dxNJUWssSVKa2j2tLfK5iBR27vsCUQvXT0ppmtPU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788528065; c=relaxed/simple; bh=qYlbXxCESLnKTi15PNafXzFG9I32g8umk7IEaNs3F3E=; h=Date:Message-ID:From:To:Cc:Subject:In-Reply-To:References: MIME-Version:Content-Type; b=czcpRzPc31EXlrQVFIX/iWNA8fdP7xA9Y1EVQnJaIDTKW9day/ouyG9aY76a/09uIyASE1aP1U6RooYlrM/RZRZc2DEfuoBo8A2rjBmG6RfYZHKP4YCneIrhntd0tRWYbJMKgLW2yJLilKL6WIIU910iuUCiiiKs05BXTucQQEw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=UxHEGf5/; 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="UxHEGf5/" Received: by smtp.kernel.org (Postfix) with ESMTPSA id ED7AD1F00A3D; Fri, 4 Sep 2026 13:21:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788528061; bh=Lv/0JtR0FodYX+QBu/pIWvc7PlCw0OO+KIN2P0yniD8=; h=Date:From:To:Cc:Subject:In-Reply-To:References; b=UxHEGf5/vmUuVHamJ+CpV7i097/cbhGNzN8V3KtbBVSxZepixnY3TDFYXTccIFaE5 Aa5GKvNRW+oawEo8iGOtKIDZLUKKjESayIKzn2sCUrbvFsplJyNmCWWB5FpfeeWc3w QgJSMamU31vlFvqymOkgZlPYHFSdmf2H10S/j/trwRpsVLNW+oC6ZI65+N7npM3WOU PqsbN5XJyrasw5jjaO9Ig7aoY7BKu2ZTMvrIr6bum5u891PnguYSMkYmjf2lSSrvdg 2qzyk5wAbbv/3joPXvkPsX5MwLUOStlCAUFSDCJFDC5wsAIz56vZQFBrmQsZaUVTQV lIQ8TUUAtPRHQ== Received: from sofa.misterjones.org ([185.219.108.64] helo=lobster-girl.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.98.2) (envelope-from ) id 1x2Tqk-00000004rhC-1x7s; Fri, 04 Sep 2026 13:20:58 +0000 Date: Fri, 04 Sep 2026 14:23:32 +0100 Message-ID: <87y0dh40bv.wl-maz@kernel.org> From: Marc Zyngier To: Mark Brown Cc: Will Deacon , Oliver Upton , Fuad Tabba , Joey Gouly , Steffen Eiden , Suzuki K Poulose , Zenghui Yu , Catalin Marinas , Mark Rutland , linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/2] KVM: arm64: Enable S1PIE for nVHE and hVHE In-Reply-To: <05f1e2f4-173a-4226-8c98-1452c20f0a47@sirena.org.uk> References: <20260904-kvm-arm64-nvhe-pie-v1-0-29d59f245e6c@kernel.org> <20260904-kvm-arm64-nvhe-pie-v1-2-29d59f245e6c@kernel.org> <86pkyt4gvt.wl-maz@kernel.org> <05f1e2f4-173a-4226-8c98-1452c20f0a47@sirena.org.uk> 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/30.1 (aarch64-unknown-linux-gnu) MULE/6.0 (HANACHIRUSATO) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=US-ASCII X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: broonie@kernel.org, will@kernel.org, oupton@kernel.org, fuad.tabba@linux.dev, joey.gouly@arm.com, seiden@linux.ibm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com, catalin.marinas@arm.com, mark.rutland@arm.com, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-kernel@vger.kernel.org X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false On Fri, 04 Sep 2026 12:48:14 +0100, Mark Brown wrote: > > On Fri, Sep 04, 2026 at 12:29:23PM +0100, Will Deacon wrote: > > On Fri, Sep 04, 2026 at 11:33:24AM +0100, Mark Brown wrote: > > > > What about pKVM, my understanding was that that is very much an ongoing > > > concern and uses the nVHE hypervisor? My expectation was that this > > > would only ever get used in hVHE configurations when people enable pKVM > > > on modern hardware, actual nVHE mode was mostly just carried along with > > > that. > > > pKVM uses hVHE wherever it can nowadays, so I'm fine with only supporting > > S1PIE on hVHE and VHE configurations if that's easier to maintain. We > > just need to make sure that the failure mode for nVHE results in the > > feature being gracefully disabled, rather than e.g. crashing or quietly > > doing the wrong thing. > > I figure that if we're supporting hVHE it will end up less complicated > to also enable nVHE, it reduces the potential for having bad or missing > fallback paths for features downstream of S1POE. It's not like it's a > huge extra bit of code and it seems likely to save hassle down the line. It's not about the code size. it's about the code being *dead*. Nobody is going to maintain this configuration, because this is a silly one. KVM with E2H==0 has reached its architectural peak years ago. We're not adding anything to it anymore, and all new architectural bits require running with E2H==1. M. -- Jazz isn't dead. It just smells funny.