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 0418D18DB32 for ; Fri, 7 Mar 2025 18:08:42 +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=1741370925; cv=none; b=XzCBNhABlz0MOe0lFj6w8DUxRQ/rj17rvsVFskERgNj6LTu2YFENIM2AtywYfl2HlfCtUZEAhXPmk9rwe2iGwQAxU74zulrVp1xv3M2/L0NzyGegdXabapNdVFFyZGNsCO7hd4SUgExLCtO7Jo7cnD2mErJjol96lKoCiYEkpLY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741370925; c=relaxed/simple; bh=LZnI5p8xIDvueq3e9u19eadPmK04KRDX31Qbc8+mNZs=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=oGUqk/Jqv72zGIGgFJzOx/jvsmACYlXSYwL7y4PHtjIAIBJJvwGGbtUMiThx+O48AV7EZJuzL3tw/88YHDn+5jd/RxvcdeoUh4v6UfyBsgHRj5BK+oT1AyQPyYDACv8Wi4BGN0orhiV9/MA/qa9SYlqVRhUTT33cRA9KmNg6OIY= 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 A60EF1A2D; Fri, 7 Mar 2025 10:08:54 -0800 (PST) Received: from [10.1.197.49] (eglon.cambridge.arm.com [10.1.197.49]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id B7E493F66E; Fri, 7 Mar 2025 10:08:35 -0800 (PST) Message-ID: Date: Fri, 7 Mar 2025 18:08:32 +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 v7 08/49] x86/resctrl: Generate default_ctrl instead of sharing it To: Reinette Chatre , x86@kernel.org, linux-kernel@vger.kernel.org Cc: Thomas Gleixner , Ingo Molnar , Borislav Petkov , H Peter Anvin , Babu Moger , 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, Shaopeng Tan , Tony Luck References: <20250228195913.24895-1-james.morse@arm.com> <20250228195913.24895-9-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 Reinette, On 07/03/2025 04:33, Reinette Chatre wrote: > On 2/28/25 11:58 AM, James Morse wrote: >> The struct rdt_resource default_ctrl is used by both the architecture >> code for resetting the hardware controls, and sometimes by the >> filesystem code as the default value for the schema, unless the >> bandwidth software controller is in use. >> >> Having the default exposed by the architecture code causes unnecessary >> duplication for each architecture as the default value must be specified, >> but can be derived from other schema properties. Now that the >> maximum bandwidth is explicitly described, resctrl can derive the default >> value from the schema format and the other resource properties. >> diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c >> index 4504a12efc97..5280a2819760 100644 >> --- a/arch/x86/kernel/cpu/resctrl/core.c >> +++ b/arch/x86/kernel/cpu/resctrl/core.c >> @@ -143,7 +143,10 @@ static inline void cache_alloc_hsw_probe(void) >> { >> struct rdt_hw_resource *hw_res = &rdt_resources_all[RDT_RESOURCE_L3]; >> struct rdt_resource *r = &hw_res->r_resctrl; >> - u64 max_cbm = BIT_ULL_MASK(20) - 1, l3_cbm_0; >> + u64 max_cbm, l3_cbm_0; >> + >> + r->cache.cbm_len = 20; >> + max_cbm = resctrl_get_default_ctrl(r); >> >> if (wrmsrl_safe(MSR_IA32_L3_CBM_BASE, max_cbm)) >> return; > > It is unclear to me why this architecture code continues to use > resctrl_get_default_ctrl() while you switched away from it in the other > architecture code. > As resctrl_get_default_ctrl() is "intended for callers that don't know > or care what the format is" [1], here it clearly is required to be a > bitmask. Using resctrl_get_default_ctrl() here also seems to contradict > your argument for not using it in cbm_validate(). [1] Sure, I'll drop this hunk on the same reasoning. Thanks, James