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 AC8B029C33C for ; Wed, 6 Aug 2025 18:07:31 +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=1754503654; cv=none; b=aG65Xj49cmOavuw7ty5xaHCQSF31jCULw5ceS1b00DZCrTJz52/v3ncht+VulWwiXe9S9AB3bfIrvCitkUlgXBZEDR3WHUDvvVVKw2lAJJfZkTjtMnYZwVAnUK8slep8TV8AiLeGS1wbuCiG0WW3pKfPHRJDmBsMInLaMw1Vbd0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754503654; c=relaxed/simple; bh=CaKjL0++SnUx3gkCzYPtfs3Eu4ajclGP5HvZ0b6cm9M=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=p3CJvOu8Koq11BzNOrnrMobXUEKGHPh/jxeFK1yPGVyvGdnOawsoP0ibn8FODQJ32wcEWnjNXfewjiIw/cSfFUJgtdOjGI52quv26JlFOiFMOAu+kY40Lp1nKr8zlGy7l1yhPUTejmqucblTRpWVBaYdlBX8GVg0SGqCieAG2QU= 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 0745819F0; Wed, 6 Aug 2025 11:07:23 -0700 (PDT) Received: from [10.1.197.43] (eglon.cambridge.arm.com [10.1.197.43]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 39D283F738; Wed, 6 Aug 2025 11:07:27 -0700 (PDT) Message-ID: <2164fca1-0a78-4c72-b93b-2b95d5f41e08@arm.com> Date: Wed, 6 Aug 2025 19:07:25 +0100 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: [RFC PATCH 17/36] arm_mpam: Add cpuhp callbacks to probe MSC hardware To: Baisheng Gao Cc: amitsinght@marvell.com, baolin.wang@linux.alibaba.com, ben.horgan@arm.com, bobo.shaobowang@huawei.com, carl@os.amperecomputing.com, dave.martin@arm.com, david@redhat.com, dfustini@baylibre.com, kobak@nvidia.com, lcherian@marvell.com, lecopzerc@nvidia.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, peternewman@google.com, quic_jiles@quicinc.com, rex.nie@jaguarmicro.com, robh@kernel.org, rohit.mathew@arm.com, scott@os.amperecomputing.com, sdonthineni@nvidia.com, shameerali.kolothum.thodi@huawei.com, tan.shaopeng@fujitsu.com, xhao@linux.alibaba.com, zengheng4@huawei.com, hao_hao.wang@unisoc.com References: <20250711183648.30766-18-james.morse@arm.com> <20250729061127.206-1-baisheng.gao@unisoc.com> Content-Language: en-GB From: James Morse In-Reply-To: <20250729061127.206-1-baisheng.gao@unisoc.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Hi Baisheng, On 29/07/2025 07:11, Baisheng Gao wrote: >> Because an MSC can only by accessed from the CPUs in its cpu-affinity >> set we need to be running on one of those CPUs to probe the MSC >> hardware. >> >> Do this work in the cpuhp callback. Probing the hardware will only >> happen before MPAM is enabled, walk all the MSCs and probe those we can >> reach that haven't already been probed. >> >> Later once MPAM is enabled, this cpuhp callback will be replaced by >> one that avoids the global list. >> >> Enabling a static key will also take the cpuhp lock, so can't be done >> from the cpuhp callback. Whenever a new MSC has been probed schedule >> work to test if all the MSCs have now been probed. >> diff --git a/drivers/platform/arm64/mpam/mpam_devices.c b/drivers/platform/arm64/mpam/mpam_devices.c >> index 0d6d5180903b..89434ae3efa6 100644 >> --- a/drivers/platform/arm64/mpam/mpam_devices.c >> +++ b/drivers/platform/arm64/mpam/mpam_devices.c >> @@ -513,9 +541,84 @@ int mpam_ris_create(struct mpam_msc *msc, u8 ris_idx, >> +static void mpam_register_cpuhp_callbacks(int (*online)(unsigned int online), >> + int (*offline)(unsigned int offline)) >> +{ >> + mutex_lock(&mpam_cpuhp_state_lock); >> + if (mpam_cpuhp_state) { >> + cpuhp_remove_state(mpam_cpuhp_state); >> + mpam_cpuhp_state = 0; >> + } >> + >> + mpam_cpuhp_state = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "mpam:online", >> + online, offline); >> + if (mpam_cpuhp_state <= 0) { >> + pr_err("Failed to register cpuhp callbacks"); >> + mpam_cpuhp_state = 0; >> + } >> + mutex_unlock(&mpam_cpuhp_state_lock); >> } >> >> static int mpam_dt_count_msc(void) >> @@ -797,6 +900,46 @@ static struct platform_driver mpam_msc_driver = { >> +static void mpam_enable_once(void) >> +{ >> + mutex_lock(&mpam_cpuhp_state_lock); >> + cpuhp_remove_state(mpam_cpuhp_state); >> + mpam_cpuhp_state = 0; >> + mutex_unlock(&mpam_cpuhp_state_lock); > Deleting the above 4 lines? > The mpam_cpuhp_state will be removed firstly in mpam_register_cpuhp_callbacks > if the mpam_cpuhp_state isn't 0. Yup - this is a pointless appendage because of the way the code evolved! Thanks for catching it James >> + >> + mpam_register_cpuhp_callbacks(mpam_cpu_online, mpam_cpu_offline); >> + >> + pr_info("MPAM enabled\n"); >> +}