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 806DDC55171 for ; Sat, 1 Aug 2026 00:24:38 +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=kMABh0sp2CLAMvAaOZJ6Os12WEF9NHcunqGFfBVy2Xc=; b=2LgUAGiZvAhB3tvlowsHeeL/at 9OKmQufrHH9JsJu20MR8x/ksZC6k6zZwZrqk89wBO48wWX7G7NJZJxZb+AU9qRJ4SHxHLqKOHXSpF 6tLcO/J9Hs6BXb1kpZ3YuDln1G4lyC5ResYejs8acZeyPF7fcz14KqXHjiaR+3MP5lQk0OedqQZLn gmAz6nVkjLgoFUqQfRCsruIlW2wYVt2lpq29nWAsxc0nd12LKathn5tfiXkPXNDRCsUQPc0LiXbhn oYXZP7AIFlHbt+fLeODOA552alMjOZn8YDKxq6MDqtBKSzUcPRpHIpLPmG/unhzpsjU+thc8v6Nkk 9L3jRysA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wpxWX-0000000Dl8V-25iJ; Sat, 01 Aug 2026 00:24:21 +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 1wpxWS-0000000Dl87-2VZg for linux-arm-kernel@lists.infradead.org; Sat, 01 Aug 2026 00:24:18 +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 051451595; Fri, 31 Jul 2026 17:24:10 -0700 (PDT) Received: from [10.211.55.3] (unknown [10.57.65.21]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 677313F66F; Fri, 31 Jul 2026 17:24:12 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1785543854; bh=eDQIXM1OVa//5nRVyjR/EED0Zzmr4Ifp8MMz5b+Y97c=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=ndvYob/B08rDgFN8UGLk9cCVxgEtIwerbLtVMtqpv8KMaSRifmxLeS4Hg+poraF5I s1gHU28NCtlOZPTNDmaYiRGVqMtBgo2zu49os5T0KXZY6vLQqKvRc0xz6kzyKZoSDC sh4jKjuZtSt0HJ5ERhigOeOMpfuq/56s8owJwFGQ= Message-ID: <0fca2908-e8eb-4842-9a9b-a876fa459e02@arm.com> Date: Sat, 1 Aug 2026 01:23:57 +0100 MIME-Version: 1.0 User-Agent: Thunderbird Daily Subject: Re: [PATCH 6/6] arm_mpam: Apply T241-MPAM-6 to 63-bit counters To: will@kernel.org Cc: james.morse@arm.com, fenghuay@nvidia.com, linux-arm-kernel@lists.infradead.org, andre.przywara@arm.com, gshan@redhat.com, tan.shaopeng@jp.fujitsu.com, sdonthineni@nvidia.com, jonathan.cameron@oss.qualcomm.com References: <20260731175243.904730-1-ben.horgan@arm.com> <20260731175243.904730-7-ben.horgan@arm.com> Content-Language: en-US From: Ben Horgan In-Reply-To: <20260731175243.904730-7-ben.horgan@arm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260731_172416_867070_6551BD87 X-CRM114-Status: UNSURE ( 8.52 ) 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: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Will, On 7/31/26 18:52, Ben Horgan wrote: > From: Shanker Donthineni > > T241-MPAM-6 causes all MBWU counter formats to count 64-byte > requests instead of bytes. Commit dc48eb1ff27c excluded the 63-bit > MSMON_MBWU_LWD format while scaling the shorter counters. Systems > selecting the preferred 63-bit counter consequently report bandwidth > values that are 64 times too small. > > Apply the scale to both the sampled value and overflow correction for > the 63-bit format. Unsigned arithmetic retains modulo-u64 behavior > when the scaled counter range exceeds u64. > > Fixes: dc48eb1ff27c ("arm_mpam: Add workaround for T241-MPAM-6") > Link: https://lore.kernel.org/lkml/20240816131432.993859-1-sdonthineni@nvidia.com/ > Signed-off-by: Shanker Donthineni > Reviewed-by: Fenghua Yu > Tested-by: Fenghua Yu > Reviewed-by: Ben Horgan Should have put this before, sorry. For handling the patch, Signed-off-by: Ben Horgan