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 CFE4630AD05; Tue, 30 Sep 2025 17:06:37 +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=1759251999; cv=none; b=G7ztwNsmN+bIrDSF/yHJ1AF/0LcYpU/45JAGqMwDc6dhFarKVIHX3S4Y3a6siPn7zv1lvSmkTmiLGLrrAgDU0rCYdbDeUeL8sdP7BTe1mnNGZ52Ygnl25LhcM+17oAKfV+C8+mUGDcw1BvybMzKOG5PKGFf4iIz6JU8GSKRnJjg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1759251999; c=relaxed/simple; bh=rsdmX6SyFZkENXtJNI7zZ5FCm7c9XX7EaXpvg0nvR0Q=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=oLgxlj8aI1OkQU9O0wVh9xdomAdm9DkorH5P44MhK5V/a/oF/RjGCQm1AsUbXEJKnFor0hwL+FnejfjsAco7rq71Hb4AiRf5QcT2xzAvn2e9v+eFPpBfSuRqSSwV+wA6bJUFZ5DtlwOPhDgRE3qpa4mV7knd4oUK350pgMGe2zE= 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 0FADD2008; Tue, 30 Sep 2025 10:06:29 -0700 (PDT) Received: from [10.1.197.69] (eglon.cambridge.arm.com [10.1.197.69]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 24FC73F59E; Tue, 30 Sep 2025 10:06:27 -0700 (PDT) Message-ID: Date: Tue, 30 Sep 2025 18:06:23 +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: [PATCH v2 15/29] arm_mpam: Reset MSC controls from cpu hp callbacks To: Ben Horgan , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-acpi@vger.kernel.org Cc: 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 , 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 , Catalin Marinas , Will Deacon , Greg Kroah-Hartman , Danilo Krummrich References: <20250910204309.20751-1-james.morse@arm.com> <20250910204309.20751-16-james.morse@arm.com> Content-Language: en-GB From: James Morse In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Hi Ben, On 12/09/2025 12:25, Ben Horgan wrote: > On 9/10/25 21:42, James Morse wrote: >> When a CPU comes online, it may bring a newly accessible MSC with >> it. Only the default partid has its value reset by hardware, and >> even then the MSC might not have been reset since its config was >> previously dirtyied. e.g. Kexec. >> >> Any in-use partid must have its configuration restored, or reset. >> In-use partids may be held in caches and evicted later. >> >> MSC are also reset when CPUs are taken offline to cover cases where >> firmware doesn't reset the MSC over reboot using UEFI, or kexec >> where there is no firmware involvement. >> >> If the configuration for a RIS has not been touched since it was >> brought online, it does not need resetting again. >> >> To reset, write the maximum values for all discovered controls. >> diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/mpam_devices.c >> index cd8e95fa5fd6..0353313cf284 100644 >> --- a/drivers/resctrl/mpam_devices.c >> +++ b/drivers/resctrl/mpam_devices.c >> @@ -777,8 +778,110 @@ static int mpam_msc_hw_probe(struct mpam_msc *msc) >> +static void mpam_reset_ris_partid(struct mpam_msc_ris *ris, u16 partid) >> +{ >> + struct mpam_msc *msc = ris->vmsc->msc; >> + struct mpam_props *rprops = &ris->props; >> + >> + mpam_assert_srcu_read_lock_held(); >> + >> + mutex_lock(&msc->part_sel_lock); >> + __mpam_part_sel(ris->ris_idx, partid, msc); >> + >> + if (mpam_has_feature(mpam_feat_cpor_part, rprops)) >> + mpam_reset_msc_bitmap(msc, MPAMCFG_CPBM, rprops->cpbm_wd); >> + >> + if (mpam_has_feature(mpam_feat_mbw_part, rprops)) >> + mpam_reset_msc_bitmap(msc, MPAMCFG_MBW_PBM, rprops->mbw_pbm_bits); >> + >> + if (mpam_has_feature(mpam_feat_mbw_min, rprops)) >> + mpam_write_partsel_reg(msc, MBW_MIN, 0); >> + >> + if (mpam_has_feature(mpam_feat_mbw_max, rprops)) >> + mpam_write_partsel_reg(msc, MBW_MAX, MPAMCFG_MBW_MAX_MAX); >> + >> + if (mpam_has_feature(mpam_feat_mbw_prop, rprops)) >> + mpam_write_partsel_reg(msc, MBW_PROP, 0); > If mpam_feat_ccap_part is already in enum mpam_device_features then the > reset would belong here but I expect it is better just to introduce > mpam_feat_ccap_part later (patch 21). I also commented on this feature > introduction split on patch 13. Yup, this is some knock on cleanup from that change. (I didn't understand what you meant the first time round!) >> + mutex_unlock(&msc->part_sel_lock); >> +} >> +static void mpam_reset_msc(struct mpam_msc *msc, bool online) >> +{ >> + struct mpam_msc_ris *ris; >> + >> + mpam_assert_srcu_read_lock_held(); > Unneeded? Checked in list_for_each_entry_srcu().> + So it is! I'll rip those out. They were mostly for documentation anyway. There will likely be a few others of these in the series... >> + list_for_each_entry_srcu(ris, &msc->ris, msc_list, srcu_read_lock_held(&mpam_srcu)) { >> + mpam_reset_ris(ris); >> + >> + /* >> + * Set in_reset_state when coming online. The reset state >> + * for non-zero partid may be lost while the CPUs are offline. >> + */ >> + ris->in_reset_state = online; >> + } >> +} >> + Thanks, James