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 92FE7CA0FF0 for ; Fri, 29 Aug 2025 08:59:57 +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=zLcrT93XVR//RGhRgRl+nQC7JmXUMUw3llpVTjG3V1Y=; b=WJAOsO0gHC7nKoQE3rmzkkDSeq OOb8uAa849KpHqvBVOFsohpFgwsZhbkdRM37IZYkVYLh612od06+SdgYP0foqlmJEkdr5fNxlbsik IjNnq/fZ9u9QtKEMgvJ/4ekebLnNt77Oz0nFUvGez6zpBH+UEZxn0VTOmTLo7K3L3OmWnfch6dQA7 LujRFk81GIn755slwFnRSaF1wy1mGYOARmer+WMvZBulI2p8q2xbtLfjY5teEBuOjdysdArknloeX a8qP6ZPmMZ67xWA9q+ef68sIFoAF1WGyqKsT2WTQVpHCajgf0ckcTeZyTd7jzTv+HX5ZdEjihD3E4 XLkY68Xg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1uruxd-000000053uO-1HJG; Fri, 29 Aug 2025 08:59:53 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1uruM7-00000004weh-24f5 for linux-arm-kernel@lists.infradead.org; Fri, 29 Aug 2025 08:21:10 +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 3F29F1BCB; Fri, 29 Aug 2025 01:20:56 -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 B62B73F694; Fri, 29 Aug 2025 01:20:58 -0700 (PDT) Message-ID: Date: Fri, 29 Aug 2025 09:20:57 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 07/33] arm64: kconfig: Add Kconfig entry for MPAM To: James Morse , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-acpi@vger.kernel.org, devicetree@vger.kernel.org Cc: shameerali.kolothum.thodi@huawei.com, D Scott Phillips OS , carl@os.amperecomputing.com, lcherian@marvell.com, bobo.shaobowang@huawei.com, tan.shaopeng@fujitsu.com, baolin.wang@linux.alibaba.com, Jamie Iles , Xin Hao , peternewman@google.com, dfustini@baylibre.com, amitsinght@marvell.com, David Hildenbrand , Rex Nie , Dave Martin , Koba Ko , Shanker Donthineni , fenghuay@nvidia.com, baisheng.gao@unisoc.com, Jonathan Cameron , Rob Herring , Rohit Mathew , Rafael Wysocki , Len Brown , Lorenzo Pieralisi , Hanjun Guo , Sudeep Holla , Krzysztof Kozlowski , Conor Dooley , Catalin Marinas , Will Deacon , Greg Kroah-Hartman , Danilo Krummrich References: <20250822153048.2287-1-james.morse@arm.com> <20250822153048.2287-8-james.morse@arm.com> <0c8a6a7c-3d0d-4093-8bc5-3a04f70b00fa@arm.com> From: Ben Horgan Content-Language: en-US In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250829_012107_614651_C0A0118A X-CRM114-Status: GOOD ( 21.46 ) 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, On 8/28/25 16:58, James Morse wrote: > Hi Ben, > > On 27/08/2025 09:53, Ben Horgan wrote: >> On 8/22/25 16:29, James Morse wrote: >>> The bulk of the MPAM driver lives outside the arch code because it >>> largely manages MMIO devices that generate interrupts. The driver >>> needs a Kconfig symbol to enable it, as MPAM is only found on arm64 >>> platforms, that is where the Kconfig option makes the most sense. >>> >>> This Kconfig option will later be used by the arch code to enable >>> or disable the MPAM context-switch code, and registering the CPUs >>> properties with the MPAM driver. > >>> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig >>> index e9bbfacc35a6..658e47fc0c5a 100644 >>> --- a/arch/arm64/Kconfig >>> +++ b/arch/arm64/Kconfig >>> @@ -2060,6 +2060,23 @@ config ARM64_TLB_RANGE >>> ARMv8.4-TLBI provides TLBI invalidation instruction that apply to a >>> range of input addresses. >>> >>> +config ARM64_MPAM >>> + bool "Enable support for MPAM" >>> + help >>> + Memory Partitioning and Monitoring is an optional extension >>> + that allows the CPUs to mark load and store transactions with >>> + labels for partition-id and performance-monitoring-group. >>> + System components, such as the caches, can use the partition-id >>> + to apply a performance policy. MPAM monitors can use the >>> + partition-id and performance-monitoring-group to measure the >>> + cache occupancy or data throughput. >>> + >>> + Use of this extension requires CPU support, support in the >>> + memory system components (MSC), and a description from firmware >>> + of where the MSC are in the address space. >>> + >>> + MPAM is exposed to user-space via the resctrl pseudo filesystem. >>> + >>> endmenu # "ARMv8.4 architectural features" > >> Should this be moved to "ARMv8.2 architectural features" rather than the >> 8.4 menu? In the arm reference manual, version L.b, I see FEAT_MPAM >> listed in the section A2.2.3.1 Features added to the Armv8.2 extension >> in later releases. > > Hmmm, I don't think we've done that anywhere else. I'm only aware of one v8.2 platform > that had it, and those are not widely available. As it was a headline v8.4 feature I'd > prefer to keep it there. > > I think its more confusing to put it under v8.2! Ok, always best to minimise confusion. Keep it in v8.4. > > Thanks, > > James -- Thanks, Ben