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 8C4F8C433EF for ; Fri, 22 Apr 2022 16:28:15 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id D7F3D49EB1; Fri, 22 Apr 2022 12:28:14 -0400 (EDT) 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 Cf73StCTDSwE; Fri, 22 Apr 2022 12:28:13 -0400 (EDT) Received: from mm01.cs.columbia.edu (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id A9BBA4B206; Fri, 22 Apr 2022 12:28:13 -0400 (EDT) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id D03A449ED8 for ; Fri, 22 Apr 2022 12:28:12 -0400 (EDT) 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 4u2Fjpg7F0fn for ; Fri, 22 Apr 2022 12:28:11 -0400 (EDT) Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by mm01.cs.columbia.edu (Postfix) with ESMTPS id 8672D49EB1 for ; Fri, 22 Apr 2022 12:28:11 -0400 (EDT) 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 1AED4B831AD; Fri, 22 Apr 2022 16:28:10 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D57AEC385A4; Fri, 22 Apr 2022 16:28:05 +0000 (UTC) Date: Fri, 22 Apr 2022 17:28:02 +0100 From: Catalin Marinas To: Mark Brown Subject: Re: [PATCH v14 16/39] arm64/sme: Implement traps and syscall handling for SME Message-ID: References: <20220419112247.711548-1-broonie@kernel.org> <20220419112247.711548-17-broonie@kernel.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20220419112247.711548-17-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 , Luca Salabrino 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 Tue, Apr 19, 2022 at 12:22:24PM +0100, Mark Brown wrote: > By default all SME operations in userspace will trap. When this happens > we allocate storage space for the SME register state, set up the SVE > registers and disable traps. We do not need to initialize ZA since the > architecture guarantees that it will be zeroed when enabled and when we > trap ZA is disabled. > > On syscall we exit streaming mode if we were previously in it and ensure > that all but the lower 128 bits of the registers are zeroed while > preserving the state of ZA. This follows the aarch64 PCS for SME, ZA > state is preserved over a function call and streaming mode is exited. > Since the traps for SME do not distinguish between streaming mode SVE > and ZA usage if ZA is in use rather than reenabling traps we instead > zero the parts of the SVE registers not shared with FPSIMD and leave SME > enabled, this simplifies handling SME traps. If ZA is not in use then we > reenable SME traps and fall through to normal handling of SVE. > > Signed-off-by: Mark Brown Re-adding my reviewed-by following the update. Reviewed-by: Catalin Marinas _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm