From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 284CA257852; Thu, 28 Aug 2025 15:58:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756396722; cv=none; b=oMn29bgEaLQ+fiNjICsETBYGeFszTdUVOVE1z8xcYgLSKUTpd7LYXoVk1XWNfIwyxpc1PQ488d9wc8ZJNn65i6ddcZYaM6kGydJ2LLk+h6taf6TLmkuqB00acBcQGdKLnNtJG/LcVD8Ir2f35cOb88uuhnrOXKGUeGpJUfzsa7o= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756396722; c=relaxed/simple; bh=L6c6sYKZ2Bo7HkfwuY5ExJZmk8rqe6Wfutw8lY2CxwQ=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=oW5zIXwQZktRtDWTjJnEHduxGAfcys4NYVHCZKbgxFGiv+SP3LQ2Ir6RCgPQo2k+agelCQZlLdQlCMM8pPi855lYNMzLtyDlemqopeQ4yeKC9EzqocVmUbUy2TI/4x+XVfz33WKqR7a7ipUJ6rWvuvsN1Zcgfkx9qt5pPeJnSQ0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com 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 3A6912C40; Thu, 28 Aug 2025 08:58:28 -0700 (PDT) Received: from [10.1.196.42] (eglon.cambridge.arm.com [10.1.196.42]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 322993F694; Thu, 28 Aug 2025 08:58:27 -0700 (PDT) Message-ID: Date: Thu, 28 Aug 2025 16:58:26 +0100 Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 07/33] arm64: kconfig: Add Kconfig entry for MPAM To: Ben Horgan , 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> Content-Language: en-GB From: James Morse In-Reply-To: <0c8a6a7c-3d0d-4093-8bc5-3a04f70b00fa@arm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit 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! Thanks, James