From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 571881A0712 for ; Fri, 13 Mar 2026 09:06:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773392778; cv=none; b=czcLb4pir+5NBlr2ADrCvjxKnHBHPCiqCoV1TbUg27gk3wcjY3skrLb48eIJ/5aY1/Vw2Hz7tTFqhW/NuXQn9CYFMC56w4PowxsztwW4Fq12vkZAr7beIATXfoJqkccc1pke5jpnSzXCdGXY7G78UHcCIdT8mVfvc72no42B9l8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773392778; c=relaxed/simple; bh=ApLUkt+F3u3gzBaangDP3HWLIX1uwr3fS7gulGMSVsM=; h=Date:Message-ID:From:To:Cc:Subject:In-Reply-To:References: MIME-Version:Content-Type; b=X/EpHQlSNxB7Fgo0DjoAU8hS9g/2N/ZvpDFwUMIm6/UlPPWv6KFRXgyYrl4nXnlMT46b51P3BFDKw/rpg961Mx42pwKvCwG52iozBQ26Brwz3LLQQXoNbys2vBm/CoJ6hQLLeL5V+gs8cOXYoJ7TKDxEe0XSi7o97pV8cUInEAw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=YGezCFoa; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="YGezCFoa" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E6ED6C19421; Fri, 13 Mar 2026 09:06:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1773392778; bh=ApLUkt+F3u3gzBaangDP3HWLIX1uwr3fS7gulGMSVsM=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=YGezCFoazK+VdxfRZrKwmQniEkzkOLW2rFO8xOoMZPnpwVK7g7wpOALwucLzJzO3p pK3n2iljrFzpiraCETyaa+419LqKMyLKKytRoJq+HSHD96RWMNGilV7f3metkM/6Z6 5tt8eGJANUetDvdkvOK5ATCORERP1xM8ZwxBnbMi4A6AkedWJ+mz5u028jTm7cArcv RtNi1UWsPEcGJ2B/lILRfbdqxckx9LwqaJwPwitQYU2s3wD+an5feVuwhi342u6+oC WIAsQLct1yfaeXP3WSUSj67MeWm9VHWT/K3sMufJj4dqapS2RfiayQLouEMotO7E8R AyHcxPve3zKyw== Received: from [84.207.203.52] (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 1w0yTH-00000001avQ-2egT; Fri, 13 Mar 2026 09:06:15 +0000 Date: Fri, 13 Mar 2026 09:06:14 +0000 Message-ID: <87ms0ccd4p.wl-maz@kernel.org> From: Marc Zyngier To: Anshuman Khandual Cc: linux-arm-kernel@lists.infradead.org, Catalin Marinas , Will Deacon , Oliver Upton , Mark Rutland , linux-kernel@vger.kernel.org Subject: Re: [PATCH] arm64: Clear VTCR_EL2 in __init_el2_stage2() In-Reply-To: <949f02cf-9f26-40ba-9c68-1742e335e2b9@arm.com> References: <20260313053857.1277828-1-anshuman.khandual@arm.com> <87sea4chrw.wl-maz@kernel.org> <87o6kscfon.wl-maz@kernel.org> <949f02cf-9f26-40ba-9c68-1742e335e2b9@arm.com> 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: 84.207.203.52 X-SA-Exim-Rcpt-To: anshuman.khandual@arm.com, linux-arm-kernel@lists.infradead.org, catalin.marinas@arm.com, will@kernel.org, oupton@kernel.org, mark.rutland@arm.com, 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, 13 Mar 2026 08:39:46 +0000, Anshuman Khandual wrote: > > > > On 13/03/26 1:41 PM, Marc Zyngier wrote: > > On Fri, 13 Mar 2026 07:54:04 +0000, > > Anshuman Khandual wrote: > >> > >> But it can be argued that these registers > >> need not have to be cleared now and can just be initialised before > >> setting up HCR_EL2_VM itself. In which case should we drop > >> __init_el2_stage2() entirely ? > > > > And something worth thinking of: the role of VTTBR_EL2.VMID when > > HCR_EL2.VM is 0. > > Are you suggesting that VTTBR_EL2_VMID needs to be 0 even when > HCR_EL2_VM = 0 because of its corresponding TLB entries ? But > during system boot such possibilities might not really exist ? This is not a suggestion. This is an architectural requirement. TLBs filled from the EL1&0 translation regime are always tagged by VMID when EL2 is implemented, irrespective of HCR_EL2.VM. M. -- Jazz isn't dead. It just smells funny.