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 A7D75C48260 for ; Thu, 8 Feb 2024 12:30:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; 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=n75NRHYIkZYpFN5gtSwjUcqVO4tyXrLY9Mbz3NvFpzg=; b=jBcktIuZ2qRD/7 8xkgz1xk0Say2KYG+RHT/Z6tiQj+cyyrN/utImlMatwnyjxv0iuPQVyc2CS+71zgg1/CCB12FVMA4 YwuL/PUN38GFQv9QG/wJK3cp8W4hmVygojfUL8ME9Zj66RY0y/yESQ42l6bRGegS7XfK+Hl58FFuF 4847euUv4X+HGAgGZMTLfCmTto+Epwf5RXFhz8hbrPdfZwafho5ViqhmDD+kb4+gY89foNEF57HHV 0icemJ/eYdl+CAEsnhJsAA6qfKwP4qHN/DC61gPpc2Ax8YGqel7wCt9vR+8neG/DLxkX5tFm7sJOn FyOmDyGzI66+TDAYhWuQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1rY3Xw-0000000Dj7G-3Ct6; Thu, 08 Feb 2024 12:30:28 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1rY3Xt-0000000Dj6s-3dZn for linux-arm-kernel@lists.infradead.org; Thu, 08 Feb 2024 12:30:27 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id F19371FB; Thu, 8 Feb 2024 04:31:05 -0800 (PST) Received: from arm.com (RQ4T19M611.cambridge.arm.com [10.1.31.53]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 7D9233F5A1; Thu, 8 Feb 2024 04:30:22 -0800 (PST) Date: Thu, 8 Feb 2024 12:30:20 +0000 From: Catalin Marinas To: Oliver Upton Cc: Marc Zyngier , linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, Will Deacon , Mark Rutland , Suzuki K Poulose , Ard Biesheuvel , James Morse , Zenghui Yu Subject: Re: [PATCH v4 00/10] arm64: Add support for FEAT_E2H0, or lack thereof Message-ID: References: <20240122181344.258974-1-maz@kernel.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240208_043025_974915_7BFF08E0 X-CRM114-Status: GOOD ( 21.54 ) 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 Fri, Feb 02, 2024 at 07:03:25PM +0000, Oliver Upton wrote: > On Mon, Jan 22, 2024 at 06:13:34PM +0000, Marc Zyngier wrote: > > Since ARMv8.1, the architecture has grown the VHE feature, which makes > > EL2 a superset of EL1. With ARMv9.5 (and retroactively allowed from > > ARMv8.1), the architecture allows implementations to have VHE as the > > *only* implemented behaviour, meaning that HCR_EL2.E2H can be > > implemented as RES1. As a follow-up, HCR_EL2.NV1 can also be > > implemented as RES0, making the VHE-ness of the architecture > > recursive. > > > > This has a number of consequences, both at boot time and for KVM, > > though the changes at that level are pretty minor. > > > > The real meat of this series is on the cpufeature front, as FEAT_E2H0 > > is a *negative* feature, where 0b1111 (-1) represents E2H being RES1 > > and 0b1110 (-2) additionally indicates that NV1 is RES0. Fun, isn't > > it? > > This looks good to me. Catalin + Will, are you comfortable with the > cpufeature changes at this point? Yes, I acked those touching the arm64 files. > No strong opinions on which tree these patches get applied to. Most of > the series is non-KVM code, so I'd understand if y'all wanted it to go > through arm64. OTOH, there are some other KVM features that might appear > in 6.9 that build on top of this, so at minimum I'd probably need a > shared branch. Please take it through the arm64 kvm tree but keep it on a separate stable branch in case I need to pull it. -- Catalin _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel