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 D5BD7C4828F for ; Fri, 2 Feb 2024 19:03:59 +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=1p9/yUYefGka5zrJwXws8Vld0EPe7r/ZXrlMqqvnOhc=; b=lSydyOi32WKDu7 L9X3qZcxHgvjvBNTHEh9sDkKDnt+wjVhEs8c136a3UyQkK/hvu6FdWCZ/4AB+JyuV7tEH1cbOH7TS a+5IVzmSV6K6hLKv5Ytm3Lpvp0DMgYN9/VNjOApZooA1PkEIqvM4htL6ThbLqHiWi8XanVGsKYO5w w3Gc/1+bkFZufWw3SOV+IZsWZvike+5iPkGLW4qbNW1T2P17hN/HSIop9toC2rateF707/GLoxl+7 NmNbikUjZtYJxp6EQc1ojSoO8kHmVRYFv25uzMKFBEUumoYC1ukGkrwkeHAfxg7vRPHXsIz7jtMM8 bWtYaAyQiQHBpO3xoIiQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1rVyp9-0000000D4Bw-1Ufy; Fri, 02 Feb 2024 19:03:39 +0000 Received: from out-183.mta0.migadu.com ([91.218.175.183]) by bombadil.infradead.org with esmtps (Exim 4.97.1 #2 (Red Hat Linux)) id 1rVyp5-0000000D49E-3Gk9 for linux-arm-kernel@lists.infradead.org; Fri, 02 Feb 2024 19:03:37 +0000 Date: Fri, 2 Feb 2024 19:03:25 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1706900610; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=evBFkKEKKP0LsMc6bHbbUzAu/6aHsfdZ5OMDYq25fsg=; b=lsO1ux64yYk95nCObYCdu+AL+bunpDjSLs4b7DNXZpKu2ZJB288FnWR9JmxQ3nKHSwR1S7 8+iAOa707aux0vMGHmETQf+FvPmw6UOhjsGIUstEV+KoYBp+jIDoLSAMf9ahIsVcx1R+vt /EiAiNfRyyuasRSLLEYJTpDqlNOKM/A= X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Oliver Upton To: Marc Zyngier Cc: linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, Catalin Marinas , 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: <20240122181344.258974-1-maz@kernel.org> X-Migadu-Flow: FLOW_OUT X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240202_110336_413462_E5A465D6 X-CRM114-Status: GOOD ( 15.67 ) 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 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? 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. LMK what you think. -- Thanks, Oliver _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel