From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.12]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 442F23630AE for ; Wed, 29 Jul 2026 17:28:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.12 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785346083; cv=none; b=d4oHJ7Kyj4L/U8/YjN0awQFhZheS9SbSvb3oZPlGxAGp7qKLgiGP/tT2hE6Ca5MhLljTKFU6ecEaC+koWvbwhpHRE1NVF3USyKtD5yF5tRhVIsjTtTlpbEz1GPNguXDWRc78c7vFuXvJprziI1+x2X8/NFY0LiiwZp65hz9Nzpc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785346083; c=relaxed/simple; bh=WcPgE1DJLY7e8F5Lz0+pqsvQduengKJ6Gliu/YMdQ4k=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Tde63whReDEn4TdwYBEdcipxOF7SPFTt4LOLUkEdU2Jzykhi/BvqKAgNAvdvydoLmlrYJqx0rVRH+24K/ZhqgnuW9b8zxAY9FHqxt9NnRFN7lh10ogmYCX8R1GMNckdZdQ264oX6npa0TFhpCv0EnMMQo1jphEFxpEmQ4JuwD0s= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com; spf=pass smtp.mailfrom=intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=eKt3IdUp; arc=none smtp.client-ip=198.175.65.12 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="eKt3IdUp" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1785346082; x=1816882082; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=WcPgE1DJLY7e8F5Lz0+pqsvQduengKJ6Gliu/YMdQ4k=; b=eKt3IdUpqROxsBw914d+BGsqIOc6VoI5BFgh5GvFWYIidugdex/ar9pg JFtfpIy15rKUCiqeNRE3Toeqn6OpvbA82q5Yn5RQtWSg2/YGJFreLtX9D xQwlFigFcaBrxLGI/fLiOJqlJf6HX2qX+967Q8/o/C69a4BSVskGOlxny KQvyoScsNqzN5UIoyJRBfQkB5rF4qADBhdfH6PRnZDZyMQKbKMIE/9A0C Pf4U8fzW7lOrC15USNvLPYeffX0dK8LanKSrMBA18qdsenJgnNAZn6MjQ uVffyPF9czDX+WfK7JY6oFC7AGs8q474HKB8XGwoF150bn0k0wkesv6Dd g==; X-CSE-ConnectionGUID: MuuTajpuSLen/Ufbc683eg== X-CSE-MsgGUID: q0Y0KdCgTCeX7iR/FGEIXA== X-IronPort-AV: E=McAfee;i="6800,10657,11859"; a="97473553" X-IronPort-AV: E=Sophos;i="6.25,192,1779174000"; d="scan'208";a="97473553" Received: from fmviesa004.fm.intel.com ([10.60.135.144]) by orvoesa104.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Jul 2026 10:28:00 -0700 X-CSE-ConnectionGUID: URrAjOEFQK6z0d6vKDSVjg== X-CSE-MsgGUID: jaxe6E/LTdK4AP4vUWJs8A== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.25,192,1779174000"; d="scan'208";a="262024545" Received: from iherna2-mobl4.amr.corp.intel.com (HELO agluck-desk3.home.arpa) ([10.124.223.238]) by fmviesa004-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Jul 2026 10:28:00 -0700 From: Tony Luck To: Fenghua Yu , Reinette Chatre , Maciej Wieczor-Retman , Peter Newman , James Morse , Babu Moger , Drew Fustini , Dave Martin , Chen Yu , David E Box , x86@kernel.org Cc: Christoph Hellwig , linux-kernel@vger.kernel.org, patches@lists.linux.dev, Tony Luck Subject: [PATCH v10 01/17] x86/resctrl: Fix enumeration of number of supported RMIDs Date: Wed, 29 Jul 2026 10:27:36 -0700 Message-ID: <20260729172752.11561-2-tony.luck@intel.com> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260729172752.11561-1-tony.luck@intel.com> References: <20260729172752.11561-1-tony.luck@intel.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit There is a multi-step decision tree for enumeration on X86 of Intel Resource Director Technology (RDT) also known as AMD Platform Quality of Service (PQOS) First check CPUID(0x7,0x0).EBX{12} (Linux feature flag X86_FEATURE_CQM). If this is "0" no monitoring features are supported. If it is "1" then monitoring is supported, the IA32_PQR_ASSOC MSR exists, and the RMID field can be written with values from zero to the value enumerated in CPUID(0xF,0x0).EBX. Second check CPUID(0xF,0x0).EDX{1} (Linux feature flag X86_FEATURE_CQM_LLC). If this is "1" then one or more L3 cache monitoring features exist and further enumeration from CPUID(0xF,0x1) provides information about L3 monitoring features. Linux skips the check for X86_FEATURE_CQM and begins with step two checking X86_FEATURE_CQM_LLC. This is a problem for systems that do not support any L3 monitoring features (or have disabled them with the kernel boot parameter "clearcpuid=cqm_llc") but do support other features such as Application Energy Telemetry. On such a system cpuinfo_x86::x86_cache_max_rmid is incorrectly set to "-1". Correct the checks to follow guidance from the Intel Software Developer's manual and AMD Architecture Programmer's Manual. Fixes: cbc82b172638 ("x86: Add support for Intel Cache QoS Monitoring (CQM) detection") Signed-off-by: Tony Luck --- v10: New patch so that boot_cpu_data.x86_cache_max_rmid is useful even on systems that don't have cache monitoring. Perhaps only worthy of backport to older kernels if taking the rest of this series. arch/x86/kernel/cpu/resctrl/core.c | 9 +++------ 1 file changed, 3 insertions(+), 6 deletions(-) diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c index 9b9495174041..e3544c99cff1 100644 --- a/arch/x86/kernel/cpu/resctrl/core.c +++ b/arch/x86/kernel/cpu/resctrl/core.c @@ -1075,20 +1075,17 @@ static enum cpuhp_state rdt_online; /* Runs once on the BSP during boot. */ void resctrl_cpu_detect(struct cpuinfo_x86 *c) { - if (!cpu_has(c, X86_FEATURE_CQM_LLC) && !cpu_has(c, X86_FEATURE_ABMC)) { + if (!cpu_has(c, X86_FEATURE_CQM)) { c->x86_cache_max_rmid = -1; c->x86_cache_occ_scale = -1; c->x86_cache_mbm_width_offset = -1; return; } - /* will be overridden if occupancy monitoring exists */ + /* May be overridden if L3 monitoring exists and supports fewer RMIDs. */ c->x86_cache_max_rmid = cpuid_ebx(0xf); - if (cpu_has(c, X86_FEATURE_CQM_OCCUP_LLC) || - cpu_has(c, X86_FEATURE_CQM_MBM_TOTAL) || - cpu_has(c, X86_FEATURE_CQM_MBM_LOCAL) || - cpu_has(c, X86_FEATURE_ABMC)) { + if (cpu_has(c, X86_FEATURE_CQM_LLC) || cpu_has(c, X86_FEATURE_ABMC)) { u32 eax, ebx, ecx, edx; /* QoS sub-leaf, EAX=0Fh, ECX=1 */ -- 2.55.0