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 D8849EB64DA for ; Thu, 20 Jul 2023 12:27:40 +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-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-Transfer-Encoding:Content-ID:Content-Description:Resent-Date :Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=daTa396rdHY7qsj623rfUYha1S3N47jW89b+szwI6Gs=; b=YXIwxGGX5A4A8j42OEcrr3CIEg 7xr1BjxO7gHApSnwbgmhRiYOpW/sfkgs5QCYcCGFlzm/fXKxOusbK8lYN9ILTiUx4fI5dPLrIF1s9 mKNxDlXVIqGs2AJv9jJswErhNck1ZTIdmEEvXdWxMb2EJfjBlXVo2YFHUI4WloFFYZf2njJYW/Or2 q2Duf7Y+nVvj7dxsrwzhMyEp253NGpFcFfEKevgfP2/TWWvtg17s0RjB9UCbWqCQmq/tt8eb8rktY Xl0jntoWmeA/rHqyhkRLON/ndXsqMXKxZd3bbg8UR1wI54KYx6C6giXYhob0BmOh9pwh5dxLiseVs R4oEgTzQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1qMSka-00B8BU-2c; Thu, 20 Jul 2023 12:27:20 +0000 Received: from dfw.source.kernel.org ([139.178.84.217]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1qMSkY-00B8Au-0C for linux-arm-kernel@lists.infradead.org; Thu, 20 Jul 2023 12:27:19 +0000 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 934C161A0F; Thu, 20 Jul 2023 12:27:17 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id CB6CAC433C8; Thu, 20 Jul 2023 12:27:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1689856036; bh=rCw+psKLDBdl6kAXIJPY9IcEhZY5IxhHwvg4KUYy27Q=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=BwiRNKVJdr15gmyYf87c5qkAeJKVgK0bUhpYNBH1JoM8PiqO/jE0lKC7Dha56w0BT 7O/vwi9WBffNUurAE/FZjy7XJUz2CFkFxvVB7vCi6Ru6h6KIU083RJOIryIfENkD1X oTENDWIdJqSXUAPOfCcYOIf/NGXgzL/80xC+2m1uOmTieNUgd9F7ACJib/Zssmi7kJ h8IWNcPMAhii51lmlhTmMjHATZ9KWJgeQ7ghBT/98FD0E6coqekAxPi+iTbkKn/6IH LI7B5Qlh4ewNKw5JkkAM1YGH45chzb7Sy41C856SadZ3c4y6onctYse05VbAblsj7m JvR4b6hrEFSTA== Date: Thu, 20 Jul 2023 13:27:10 +0100 From: Mark Brown To: Will Deacon Cc: Catalin Marinas , Shuah Khan , David Spickett , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH 1/3] arm64/fpsimd: Ensure SME storage is allocated after SVE VL changes Message-ID: <3ce4fc14-bd43-47e9-aa37-59bb3cd5d051@sirena.org.uk> References: <20230713-arm64-fix-sve-sme-vl-change-v1-0-129dd8611413@kernel.org> <20230713-arm64-fix-sve-sme-vl-change-v1-1-129dd8611413@kernel.org> <20230720105235.GD11034@willie-the-truck> MIME-Version: 1.0 In-Reply-To: <20230720105235.GD11034@willie-the-truck> X-Cookie: Ginger snap. X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230720_052718_163153_F4A8F37F X-CRM114-Status: GOOD ( 15.06 ) 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: multipart/mixed; boundary="===============4859316798755509088==" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org --===============4859316798755509088== Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="CyMXBdFoH12etnuE" Content-Disposition: inline --CyMXBdFoH12etnuE Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Thu, Jul 20, 2023 at 11:52:36AM +0100, Will Deacon wrote: > On Thu, Jul 13, 2023 at 09:06:04PM +0100, Mark Brown wrote: > > Since the ABI does not specify that changing the SVE vector length disturbs > > SME state, and since SVE code may not be aware of SME code in the process, > > we shouldn't simply discard any ZA state. Instead immediately reallocate > > the storage for SVE if SME is active, and disable SME if we change the SVE > > vector length while there is no SME state active. > What is the advantage of keep the old behaviour in this case? In other > words, if it's acceptable to reallocate the state when SME is active, why > not just reallocate in all cases? It was minimising the changes to the status quo given how attached people often are to these things. --CyMXBdFoH12etnuE Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAABCgAdFiEEreZoqmdXGLWf4p/qJNaLcl1Uh9AFAmS5KB4ACgkQJNaLcl1U h9C+0gf/fQxZuh51kIYByTPW3QLeYr1gzvXo8eFWKQxVOYg96BpcLaqbrocw6ZLg E0VA1/CrGB56VUq99z4VY0JUrqFoupiFJE5M5MihIAUi/0PPH9LsvzvuXuIAnrK4 CmqsOfSQTbsXhntG34dq3UkcK7VZlbK4iSZsaKig3BLtIWHBVJ1WvLpnxEkVu0Mv +qJM4GDgPeIXRKiMcxT6+Gd96Vza5VFUemOFSO9BGW5XzQE7Ix+NpT99XvE0MtwJ mTVS7V3g0F+19U08hExwfgrKS1ybUONPOqncDhwLdghsLFFOeW8WI1ttxw26afX8 UO1YvtblScSAt6Aex+N4yBujBbHMaA== =NOme -----END PGP SIGNATURE----- --CyMXBdFoH12etnuE-- --===============4859316798755509088== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel --===============4859316798755509088==--