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 D74FECD342F for ; Fri, 8 May 2026 09:38:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=Tzi78l9kdvniXfDx5aAG0mSppxO+GIQomKZynRWcED4=; b=fgM6bDvPpewkLYStq6whSg/mN3 sUS6LJmmeMb8S3zNE2FBYh3W5YqDAYBjTIvWWHG1fybeZkV9t0+9CSXl8Jjld2R0CELA03pFtU0TC l/5k6u80eqkDjlLY6eB0rZ15C5DxFOrsLPVThZF4Tc0NuacHC/t34L2BXrJl/mnlXhGDCp2GOCko9 JYNZVdrFxjjFyUjJp02sc/PDqhSwiFmpO7PukUteD7RVKF8Cvt8BLzt8bC3vWw/kHUaq8Rfu9kk/p W9u/6qzFRWVzbq0+HEDzkIm65ZKS0+Jf2VtFF35VguEvTOaBB0LntifVL/PEAnN5AZD1cAekzaP0y Thf86Ncg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wLHex-000000068CO-3SXq; Fri, 08 May 2026 09:38:15 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wLHeu-000000068Aq-2J5u for linux-arm-kernel@lists.infradead.org; Fri, 08 May 2026 09:38:14 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id BF62F1BCA; Fri, 8 May 2026 02:38:03 -0700 (PDT) Received: from [10.1.196.46] (e134344.arm.com [10.1.196.46]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 1390C3FAF5; Fri, 8 May 2026 02:38:05 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1778233089; bh=VwmEXXw0tSFbY6/crtHABcMmJJSuggKfOPrbxXWUh0c=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=vJ2W0+4lrQpJAoTPpmCQDF8cSKPXZ77CfdJnTLjAhQoAarTOYomfu4Q3VyjqfpueG VdSeWGvubLNw7ezXXAr8my+7vTJupdrKEsFyZ3wRYLcihPIcKTm1Pkwuime4URrNtd gmfJOz2D4G4SQ7VwpPpXhG9RER4HrQC7zkOImV8U= Message-ID: Date: Fri, 8 May 2026 10:37:58 +0100 MIME-Version: 1.0 User-Agent: Thunderbird Daily Subject: Re: [PATCH v2 2/2] arm_mpam: Update architecture version check for MPAM MSC To: Zeng Heng , James Morse , xry111@xry111.site, catalin.marinas@arm.com, maz@kernel.org, ardb@kernel.org, yang@os.amperecomputing.com, ryan.roberts@arm.com, kevin.brodsky@arm.com, reinette.chatre@intel.com, miko.lenczewski@arm.com, will@kernel.org, suzuki.poulose@arm.com, thuth@redhat.com, james.clark@linaro.org, lpieralisi@kernel.org, broonie@kernel.org, oupton@kernel.org, anshuman.khandual@arm.com, yeoreum.yun@arm.com, leo.yan@arm.com, mrigendra.chaubey@gmail.com, fenghuay@nvidia.com, ahmed.genidi@arm.com, mark.rutland@arm.com Cc: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, wangkefeng.wang@huawei.com References: <20260203095406.6437-1-zengheng4@huawei.com> <20260203095406.6437-3-zengheng4@huawei.com> <01ef61ca-7ba7-b282-7ec6-b1df5c301aa5@huawei.com> Content-Language: en-US From: Ben Horgan In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260508_023812_690859_A4F9A6DE X-CRM114-Status: GOOD ( 15.50 ) 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: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi James and Zeng, On 5/8/26 04:47, Zeng Heng wrote: > Hi James, > > On 2026/5/8 10:26, Zeng Heng wrote: > >>> I think its simpler to rule out the unsupported combinations, something like: >>> | static bool mpam_msc_check_aidr(struct mpam_msc *msc) >>> | { >>> |     u32 rev; >>> | >>> |     rev = __mpam_read_reg(msc, MPAMF_AIDR) & MPAMF_AIDR_ARCH_REV; >>> | >>> |      /* >>> |      * v0.0 and >v2.x aren't supported, but anything else should be backward >>> |     * compatible to v0.1 or v1.0. >>> |     */ >>> |     if (!rev) >>> |         return false; >>> |     if (rev & MPAMF_AIDR_ARCH_MAJOR_REV > MPAM_ARCHITECTURE_V1) >>> |         return false; >>> | > > Oops, after more complete version number testing, I found there's an > operator precedence issue here. The correct fix is: > >     if ((rev & MPAMF_AIDR_ARCH_MAJOR_REV) > MPAM_ARCHITECTURE_V1) >         return false; > > Note that '>' has higher precedence than '&'. Isn't it better to use FIELD_GET()? We could also avoid creating MPAMF_AIDR_ARCH_REV and use MPAMF_AIDR_ARCH_MAJOR_REV and MPAMF_AIDR_ARCH_MINOR_REV directly to stop splitting the logic over two files. mpam_msc_check_aidr() could become: static bool mpam_msc_check_aidr(struct mpam_msc *msc) { u32 aidr = __mpam_read_reg(msc, MPAMF_AIDR); u32 major = FIELD_GET(MPAMF_AIDR_ARCH_MAJOR_REV, aidr); u32 minor = FIELD_GET(MPAMF_AIDR_ARCH_MINOR_REV, aidr); /* * v0.0 and >v2.x aren't supported, but anything else should be backward * compatible to v0.1 or v1.0. */ if (!major && !minor) return false; if (major > MPAM_ARCHITECTURE_V1) return false; return true; } Thanks, Ben > > > With this fix included: > Tested-by: Zeng Heng > > >>> |     return true; >>> | } >>> >>>> +    if (!mpam_msc_check_aidr(msc)) { >>>> +        dev_err_once(dev, "MSC does not match MPAM architecture\n"); >>>>           return -EIO; >>>>       } >>> >>> I'd like to keep the 'v1.x' in this message - this should help folk with old stable >>> kernels running on new hardware work out why the feature isn't available. >>> (assuming they have some documentation that says v2.0 in it!) >>> >>> I've rebased this with the above changes, which I'll post shortly for fixes. >>> >>> >> >> Agreed. Keep the backward compatibility extension for versions >> (compatible with v0.x(x>0) and 1.x), and remove the redundant >> MPAM_ARCHITECTURE_Vx_x macro definitions. >> >> I've verified locally that everything works fine. >> > >