From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 44242CCD18A for ; Fri, 10 Oct 2025 16:55:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=WDtp7+4u+gREjQ8ljzVH11TFzpUZV8VMW0swpF2la3Q=; b=xWgm60N/SArwRLtno0NpJisFoJ onyivVGBT4AD8kcpXiUPU1rUk/k2La57eSIbDcobwzsjIF7lZMqaSPMTj0JBI3eDKUsNYqW12D/kA GYE/4gggXar8qLHPQM3eChncUxp0o1SpkHYcDQmfs9vb53+Kd2vmA/a1vNyTyXg6tDvWi8W4k76RQ 6/xHxF3iR3Kl419SfdzyBjVZ0c0gWIpTaw7P1lCDMOivBle2efsS12RCggMz3envb2eAej6fOsefU GB7WxxGOP3U6ZaS/gLUOotUrASi5IxZtgrtLy3IBbvSIUs0aelA2UriE0lNGdHUcjONlnKgbiKMr+ N6gpmFQA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1v7GPE-0000000910Z-0lDR; Fri, 10 Oct 2025 16:55:48 +0000 Received: from desiato.infradead.org ([2001:8b0:10b:1:d65d:64ff:fe57:4e05]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1v7GPD-000000090zp-07YF for linux-arm-kernel@bombadil.infradead.org; Fri, 10 Oct 2025 16:55:47 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=Content-Transfer-Encoding:Content-Type :In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date:Message-ID: Sender:Reply-To:Content-ID:Content-Description; bh=WDtp7+4u+gREjQ8ljzVH11TFzpUZV8VMW0swpF2la3Q=; b=O5yyX5Sjsfx2llO/sovHZqO5cq j4ttPnhokTXEIcvukXQrOQ45alxaYVjGx3ky35PK4JG3GgNfVnApm9rDg3K/Oe0w+hrfFCTPwcqkE 9F6QnruZoFE6VRs+TVHCj43eRTnAuPsEg2RRwmqfRWjV9lrMCi0Gzmlwj3FtgrL841CH8+i2fu5HI 4/L9hfEdPjaVbTeh5MZ34Tm0ssvyZuSs7tyQupqjlufOruEErONqr9fHVSSjoWJOte7zTgdZGXQbb ZKAbLT/c6MLQjfIRiKnK+0idWDiTs3DwqHvZ0I6nSY3WyHIgG3JVLrOfSFQ7mlhwsxbL27+Tv/8qL 7Pa6NstQ==; Received: from foss.arm.com ([217.140.110.172]) by desiato.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1v7GP9-00000002JKm-07KV for linux-arm-kernel@lists.infradead.org; Fri, 10 Oct 2025 16:55:45 +0000 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 20A61153B; Fri, 10 Oct 2025 09:55:34 -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 04CF53F66E; Fri, 10 Oct 2025 09:55:36 -0700 (PDT) Message-ID: <9ad2f065-cd13-4b9f-8b56-baa1794f0410@arm.com> Date: Fri, 10 Oct 2025 17:55:34 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 03/29] ACPI / PPTT: Find cache level by cache-id To: Fenghua Yu , 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 , 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> <20250910204309.20751-4-james.morse@arm.com> <5607ff12-1445-433a-b9f7-fffe20076be3@nvidia.com> Content-Language: en-GB From: James Morse In-Reply-To: <5607ff12-1445-433a-b9f7-fffe20076be3@nvidia.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20251010_175543_518335_0249F3BC X-CRM114-Status: GOOD ( 17.51 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Fenghua, On 02/10/2025 05:30, Fenghua Yu wrote: > On 9/10/25 13:42, James Morse wrote: >> The MPAM table identifies caches by id. The MPAM driver also wants to know >> the cache level to determine if the platform is of the shape that can be >> managed via resctrl. Cacheinfo has this information, but only for CPUs that >> are online. >> >> Waiting for all CPUs to come online is a problem for platforms where >> CPUs are brought online late by user-space. >> >> Add a helper that walks every possible cache, until it finds the one >> identified by cache-id, then return the level. >> >> Signed-off-by: James Morse > > Other than minor comment issues as follows, > > Reviewed-by: Fenghua Yu Thanks, >> diff --git a/drivers/acpi/pptt.c b/drivers/acpi/pptt.c >> index 7af7d62597df..c5f2a51d280b 100644 >> --- a/drivers/acpi/pptt.c >> +++ b/drivers/acpi/pptt.c >> @@ -904,3 +904,65 @@ void acpi_pptt_get_cpus_from_container(u32 acpi_cpu_id, cpumask_t >> *cpus) >>                        entry->length); >>       } >>   } >> + >> +/* >> + * find_acpi_cache_level_from_id() - Get the level of the specified cache >> + * @cache_id: The id field of the unified cache >> + * >> + * Determine the level relative to any CPU for the unified cache identified by >> + * cache_id. This allows the property to be found even if the CPUs are offline. >> + * >> + * The returned level can be used to group unified caches that are peers. >> + * >> + * The PPTT table must be rev 3 or later, > s/,/./ Yup, already fixed. (I need to clean my glasses more often!) >> + * >> + * If one CPUs L2 is shared with another as L3, this function will return > > This comment is not clear. Maybe it's better to say: > > + * If one CPU's L2 is shared with another CPU as L3, this function will return Sure, >> + * an unpredictable value. >> + * >> + * Return: -ENOENT if the PPTT doesn't exist, the revision isn't supported or >> + * the cache cannot be found. >> + * Otherwise returns a value which represents the level of the specified cache. >> + */ Thanks, James