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 8B3821E8324; Fri, 29 Aug 2025 08:21:05 +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=1756455667; cv=none; b=tlOhcHgIJkZ6tzOJQeNinuhUbmi0QWN0G2fdkx6MyVAZR3RKKzztkKIeh3WtFIqnyh2u4fEvr10DLo6PDKPUb4stugi+QjItSnfats8hwRBA16c4xCdTTZ7QPYcuCK7EF3stEffuU6ibqT94gV508Qh6SEd2Osej1i+GiK9ixw4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756455667; c=relaxed/simple; bh=zYHLkfGYlush9y5rRs4PMn/zClN6Vxh+u4+Ok4/hpHk=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=Ph2kbhl5K0+T00VdzBWjlr83yn4h2h2uvgTZgBvi+7PLDIvvoAAh9Caxl/+0XtqGCDbr5haoEnY8pMM7B8kqY74EdJ+nk63TktOK/I3aJyrZHLn+wNkE+ZONPpVLg/GtWnPbmrHfnWLDWSbI1de5AJVtHSlW89HPYk4coDONnzE= 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 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 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: 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 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