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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 17050C433F5 for ; Tue, 26 Oct 2021 09:07:53 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id DC98560555 for ; Tue, 26 Oct 2021 09:07:52 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org DC98560555 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=lists.infradead.org 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=aA4irthTq7isBlpFGl/momYH67OIa02v94Tr6M5oPUQ=; b=sEDTHV+sV6RwIh YoMN4oBxbS+HJl/m7hzloSOzux2J0mbseP3Mh0OqI9Lr1HZx61YDm0UxJGWBiGg7jnqXmdTbcPfWR KLGND5fIGEtdyTufWeh30dI66BetEKkv2qi4c/pw2lN3hhaJIjYfZqSzbSu5YM34gCKPkEG0n8qoY F41gFDgc9t8nqTIygH5ukDd/R95roe5Lg8fGi5Y3sXQXWHeMmuPTybhz2ksui8cvzbEapUAjOGeb0 UkzCaZBUdw0GzcEhibPWCfF+OT1Ihs/LwdQfPDpdospJpmFSq4AmCA2wNDehAeTjdEd2G6YmEn3cL IzSn5XVekFHS9hLF94qg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1mfIPa-001Aal-Hd; Tue, 26 Oct 2021 09:06:26 +0000 Received: from mail.kernel.org ([198.145.29.99]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1mfIPW-001AaS-W5 for linux-arm-kernel@lists.infradead.org; Tue, 26 Oct 2021 09:06:24 +0000 Received: by mail.kernel.org (Postfix) with ESMTPSA id ED79B60F0F; Tue, 26 Oct 2021 09:06:20 +0000 (UTC) Date: Tue, 26 Oct 2021 10:06:17 +0100 From: Catalin Marinas To: Reiji Watanabe Cc: Will Deacon , Marc Zyngier , linux-arm-kernel@lists.infradead.org, Peter Shier , Ricardo Koller , Oliver Upton , Jing Zhang , Raghavendra Rao Anata Subject: Re: [PATCH] arm64: clear_page() shouldn't use DC ZVA when DCZID_EL0.DZP == 1 Message-ID: References: <20211026034844.1393437-1-reijiw@google.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20211026034844.1393437-1-reijiw@google.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20211026_020623_074010_3CF34C12 X-CRM114-Status: UNSURE ( 7.98 ) X-CRM114-Notice: Please train this message. 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, Oct 25, 2021 at 08:48:44PM -0700, Reiji Watanabe wrote: > Currently, clear_page() uses DC ZVA instruction unconditionally. But it > should make sure that DCZID_EL0.DZP, which indicates whether or not use > of DC ZVA instruction is prohibited, is zero when using the instruction. > Use stp as memset does instead when DCZID_EL0.DZP == 1. For correctness, this is fine, but have you come across a system that has DZP == 1 (or hypervisor setting HCR_EL2.TDZ)? -- Catalin _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel