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 F0765357A26 for ; Tue, 27 Jan 2026 14:30:43 +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=1769524245; cv=none; b=HOOKVuNOoXghp+cr7CS1wy1HsYezCMDFVYPwGCAYs0jKSv5Hk2fynNhkxCs0xIujsIsKyS5qa3+hHXYUT/zrB8T+zmIwjmnmml/yrLgqsK/KKyXiEU5dCM2+m0DWK3LtJ+BypSpIl89ZRnWhddUW7P1X0UIUtI8fGdKTVdiJmjM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769524245; c=relaxed/simple; bh=IHx3RgrNW0LkKMwinSZrodra9NuV0i0xjBt23Pk73Bs=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=gkuHb0/3JPNIRPOjh0UcpadkNVAQNvLSQvBvo/1r4UQmJ2GyyAHood7jraGGl9EaY4ugySDKskWx3SD/Xh1O5Za4KEywFs/8tBmjC9Zu0F3LZik+giQiXtu71M7Du9oBNcJba8ZDmmnVz+1BdBFyxM4QJQnI12inOKmUr+zXMzo= 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 81CA31595; Tue, 27 Jan 2026 06:30:36 -0800 (PST) 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 E27663F73F; Tue, 27 Jan 2026 06:30:38 -0800 (PST) Message-ID: <37f87d5d-bd70-4b13-93e0-8024108be948@arm.com> Date: Tue, 27 Jan 2026 14:30:37 +0000 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] arm64: cpufeature: Add support for the MPAM v0.1 architecture version To: Zeng Heng , james.morse@arm.com, miko.lenczewski@arm.com, thuth@redhat.com, mark.rutland@arm.com, yeoreum.yun@arm.com, robh@kernel.org, james.clark@linaro.org, ahmed.genidi@arm.com, xry111@xry111.site, oupton@kernel.org, lpieralisi@kernel.org, catalin.marinas@arm.com, mrigendra.chaubey@gmail.com, suzuki.poulose@arm.com, maz@kernel.org, ardb@kernel.org, broonie@kernel.org, will@kernel.org, kevin.brodsky@arm.com, leo.yan@arm.com, anshuman.khandual@arm.com, yang@os.amperecomputing.com, frederic@kernel.org Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, bobo.shaobowang@huawei.com References: <20260104133434.1887677-1-zengheng4@huawei.com> From: Ben Horgan Content-Language: en-US In-Reply-To: <20260104133434.1887677-1-zengheng4@huawei.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Hi Zeng, On 1/4/26 13:34, Zeng Heng wrote: > According to the MPAM spec [1], the supported architecture versions are > v1.0, v1.1 and v0.1. MPAM versions v0.1 and v1.1 are functionally > identical, but v0.1 additionally supports the FORCE_NS feature. > > ID_AA64PR | ID_AA64PR | MPAM Extension | Notes > F0_EL1. | F1_EL1. | Architecture | > MPAM | MPAM_frac | version | > --------------------------------------------------------------------------- > 0b0000 | 0b0001 | v0.1 | MPAM v0.1 is implemented. > | | | MPAM v0.1 is the same as MPAM v1.1 > | | | with FORCE_NS which is > | | | incompatible with MPAM v1.0. > --------------------------------------------------------------------------- > 0b0001 | 0b0000 | v1.0 | MPAM v1.0 is implemented. > --------------------------------------------------------------------------- > 0b0001 | 0b0001 | v1.1 | MPAM v1.1 is implemented. > | | | MPAM v1.1 includes all features of > | | | MPAM v1.0. > | | | It must not include FORCE_NS. > > FORCE_NS is a feature that operates in EL3 mode. Consequently, the current > Linux MPAM driver is also compatible with MPAM v0.1. To support v0.1, the > existing driver which only checks ID_AA64PFR0_EL1.MPAM for the major > version needs to examine ID_AA64PFR1_EL1.MPAM_frac for the minor version > as well. > > [1] https://developer.arm.com/documentation/ddi0598/db/?lang=en > > Signed-off-by: Zeng Heng So far we've avoided added MPAM 0.1 support as we don't know of any machines using it. What's your motivation here? Do you have a machine with MPAM 0.1 that runs mainline linux? Thanks, Ben