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 mm01.cs.columbia.edu (mm01.cs.columbia.edu [128.59.11.253]) by smtp.lore.kernel.org (Postfix) with ESMTP id 45AD8C433F5 for ; Tue, 22 Feb 2022 12:53:58 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id AA48C4B0CB; Tue, 22 Feb 2022 07:53:57 -0500 (EST) X-Virus-Scanned: at lists.cs.columbia.edu Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id IoM1J2bxY3h6; Tue, 22 Feb 2022 07:53:56 -0500 (EST) Received: from mm01.cs.columbia.edu (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 6A5944A417; Tue, 22 Feb 2022 07:53:56 -0500 (EST) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 6C1CE49F28 for ; Tue, 22 Feb 2022 07:53:55 -0500 (EST) X-Virus-Scanned: at lists.cs.columbia.edu Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id X742+Tlp+V8B for ; Tue, 22 Feb 2022 07:53:54 -0500 (EST) Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by mm01.cs.columbia.edu (Postfix) with ESMTPS id 3E63449EF2 for ; Tue, 22 Feb 2022 07:53:54 -0500 (EST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 4EDF0B818FA; Tue, 22 Feb 2022 12:53:53 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3B357C340E8; Tue, 22 Feb 2022 12:53:49 +0000 (UTC) Date: Tue, 22 Feb 2022 12:53:46 +0000 From: Catalin Marinas To: Mark Brown Subject: Re: [PATCH v11 17/40] arm64/sme: Implement ZA context switching Message-ID: References: <20220207152109.197566-1-broonie@kernel.org> <20220207152109.197566-18-broonie@kernel.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20220207152109.197566-18-broonie@kernel.org> Cc: Basant Kumar Dwivedi , Will Deacon , Luis Machado , Szabolcs Nagy , Marc Zyngier , Shuah Khan , linux-arm-kernel@lists.infradead.org, linux-kselftest@vger.kernel.org, Alan Hayward , Shuah Khan , kvmarm@lists.cs.columbia.edu, Salil Akerkar X-BeenThere: kvmarm@lists.cs.columbia.edu X-Mailman-Version: 2.1.14 Precedence: list List-Id: Where KVM/ARM decisions are made List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu On Mon, Feb 07, 2022 at 03:20:46PM +0000, Mark Brown wrote: > Allocate space for storing ZA on first access to SME and use that to save > and restore ZA state when context switching. We do this by using the vector > form of the LDR and STR ZA instructions, these do not require streaming > mode and have implementation recommendations that they avoid contention > issues in shared SMCU implementations. > > Since ZA is architecturally guaranteed to be zeroed when enabled we do not > need to explicitly zero ZA, either we will be restoring from a saved copy > or trapping on first use of SME so we know that ZA must be disabled. > > Signed-off-by: Mark Brown Reviewed-by: Catalin Marinas _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm