From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=198.175.65.16 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1792443069; b=NpGK2iSQucLWiKJnWWubA8Amm7vVBTUnJKJ34HahxtUKcsxuxXiSH9+5vGYwD5/XhoNO lGeOdBYeqkNd3N8cwVsqlYSgtkC5D7cHvt2l/n7cL3owsbiIP9KrlgdN/Wji5hkZxI+DV 2xED06MeqKA56CJTGJ6ej17VoHY5wG8o0ohjohLzOrYtuPiruDcVjGZCIc8Wxw1IRw/cf z/5/hJRX6uySN0CRND/AesEFNvzQGqyYaAXTuDKkqfOh+IuYfUGdMcqjUBhDe/ig+6n6Y yLWzfT2UV2oGSj52tlt8Y0ZeXGY/qfBGerWhZza+veAlMuCAJh4IncRvMGNGASap/Kg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1792443069; h=DMARC-Filter:DKIM-Signature:X-CSE-ConnectionGUID:X-CSE-MsgGUID: X-IronPort-AV:X-IronPort-AV:Received:X-CSE-ConnectionGUID: X-CSE-MsgGUID:X-ExtLoop1:X-IronPort-AV:Received:From:To:Cc:Subject: Date:Message-ID:X-Mailer:In-Reply-To:References:MIME-Version: Content-Transfer-Encoding; bh=O8MnCrw/uL1eSqnXleCabfh7IoVpANIESipVjJiTHUo=; b=h+UQQpsjW0PbFQmjfRJbmx39AVdcUUQirnLk8HDmMRI7yvc53rGBHL/lReBHdl6ebJvG DFjHuZJdkasUxEEVCCikqAecJsmtr9U3QFRSg/G6RwvIfX25AQvY+1/O2lSqAsu56Rt/H LRFEDKRpxf24+0uOTZYZ2aeGLMkKHSvHQo7OymIdTrKCc+VKNeV58JonOBA4PEBE951lD OANCifDg5r0x+pou3NrSki9Kzx9FA/r1G576j5WcYPsGTd8Bf5Ex965vgmTb6HnF9yrGg g8ymKuakjYG9LV5yy65j2ghxsJfg3MGE/HMI+eWBIey8WrlCpYTem4xn9lPaCZSP3Dg== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=intel.com; spf=pass smtp.mailfrom=intel.com; dkim=pass header.d=intel.com header.i=@intel.com header.a=rsa-sha256 header.s=Intel header.b=RdOpDkb5; arc=none smtp.remote-ip=198.175.65.16 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.16]) (using TLSv1.2 with cipher ECDHE-ECDSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id EA74560A263A for ; Mon, 19 Oct 2026 20:51:03 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org EA74560A263A 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, unprotected) header.d=intel.com header.i=@intel.com header.a=rsa-sha256 header.s=Intel header.b=RdOpDkb5 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1792443064; x=1823979064; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=Z5eVgcyeURbp1EBb6CVVtLj6tX+2DWokVj5q47Fgr0U=; b=RdOpDkb5OQAJ0B/3S514EZF3HuwmbmsVD0o+AFKKzhw5GJrlSmLMikx2 GTTMP3J5ab/gvrUDv55cdvV8hedDavJU59ExJ7JpJF2hqLe8fdSjCezqC GOf3lG8rZ5XxZETWXBBBVFwcyq23JP0GC0IDRQIlszdutH69ey5LvwwVl pQcJguCRbv/37JR64K66kNeNYHNJ6XYzxCOmWtHtnoKZNx+6iW0snBJTb SJjjnkjwCe790knWXZIYN2IacA+yWg04nLk80CAhzMoAW4SC8wdXPYGaU s2Z0RZ/FkiWZd0p3ECsLWsUc9oRg8/66LzJlGL1KdJTif00nK5+gPeOfJ Q==; X-CSE-ConnectionGUID: uZvFIoyVQ/CgIITJsSwrpw== X-CSE-MsgGUID: d/ammBsITwuAyEKI0aFzGQ== X-IronPort-AV: E=McAfee;i="6800,10657,11940"; a="1131264" X-IronPort-AV: E=Sophos;i="6.27,168,1787036400"; d="scan'208";a="1131264" Received: from fmviesa009.fm.intel.com ([10.60.135.149]) by orvoesa108.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 19 Oct 2026 13:50:51 -0700 X-CSE-ConnectionGUID: vvV7bJFiQ4O9rkHS0bo/AA== X-CSE-MsgGUID: 2gwh/8dQR/W5fhNQ3auhRg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.27,168,1787036400"; d="scan'208";a="3008674" Received: from spandruv-mobl5.amr.corp.intel.com (HELO agluck-desk3.intel.com) ([10.124.220.87]) by smtpauth.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 19 Oct 2026 13:50:51 -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 v14 17/24] x86/resctrl: Use registered function pointers for AET enumeration Date: Mon, 19 Oct 2026 13:50:24 -0700 Message-ID: <20261019205031.16977-18-tony.luck@intel.com> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261019205031.16977-1-tony.luck@intel.com> References: <20261019205031.16977-1-tony.luck@intel.com> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit resctrl enumerates Application Energy Telemetry (AET) features by calling pmt_telemetry functions directly. pmt_telemetry now also registers these functions with resctrl when it is loaded. Calling them directly requires pmt_telemetry to be built in. In preparation for pmt_telemetry being built as a loadable module, call the registered functions instead. Serialize registration and unregistration against enumeration. Take a reference on the pmt_telemetry module before enumerating, so that the functions cannot be unregistered while resctrl uses them. AET support still requires pmt_telemetry to be built in, so it does not yet matter that the module reference is never dropped after a successful enumeration. It must be dropped on unmount before pmt_telemetry can be built as a module. Signed-off-by: Tony Luck --- v14: Updates to resolve locking problems reported by Sashiko in v13. AET is now going to use a single mutex for both registration and in a later patch for device removal. So change the name from aet_register_lock to just aet_lock. Reverse locking hierarchy between AET and pmt_telemetry. No longer OK to call into pmt_telemetry to enumerate features with the aet_lock held. Instead, make use of module pinning while holding aet_lock. New commit message --- arch/x86/kernel/cpu/resctrl/internal.h | 4 +- arch/x86/kernel/cpu/resctrl/core.c | 2 +- arch/x86/kernel/cpu/resctrl/intel_aet.c | 59 ++++++++++++++++++++++--- 3 files changed, 57 insertions(+), 8 deletions(-) diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h index c038b7d80ce3..8406addc05f5 100644 --- a/arch/x86/kernel/cpu/resctrl/internal.h +++ b/arch/x86/kernel/cpu/resctrl/internal.h @@ -234,15 +234,15 @@ void rdt_domain_reconfigure_cdp(struct rdt_resource *r); void resctrl_arch_mbm_cntr_assign_set_one(struct rdt_resource *r); #ifdef CONFIG_X86_CPU_RESCTRL_INTEL_AET -bool intel_aet_get_events(void); void __exit intel_aet_exit(void); +bool intel_aet_pre_mount(void); int intel_aet_read_event(int domid, u32 rmid, void *arch_priv, u64 *val); void intel_aet_mon_domain_setup(int cpu, int id, struct rdt_resource *r, struct list_head *add_pos); bool intel_handle_aet_option(bool force_off, char *tok); #else -static inline bool intel_aet_get_events(void) { return false; } static inline void __exit intel_aet_exit(void) { } +static inline bool intel_aet_pre_mount(void) { return false; } static inline int intel_aet_read_event(int domid, u32 rmid, void *arch_priv, u64 *val) { return -EINVAL; diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c index 0262174df7ad..ac67b4523b2d 100644 --- a/arch/x86/kernel/cpu/resctrl/core.c +++ b/arch/x86/kernel/cpu/resctrl/core.c @@ -795,7 +795,7 @@ void resctrl_arch_pre_mount(void) struct rdt_resource *r = &rdt_resources_all[RDT_RESOURCE_PERF_PKG].r_resctrl; int cpu; - if (!intel_aet_get_events()) + if (!intel_aet_pre_mount()) return; /* diff --git a/arch/x86/kernel/cpu/resctrl/intel_aet.c b/arch/x86/kernel/cpu/resctrl/intel_aet.c index 996a7ee544bf..26406e18d5ed 100644 --- a/arch/x86/kernel/cpu/resctrl/intel_aet.c +++ b/arch/x86/kernel/cpu/resctrl/intel_aet.c @@ -12,6 +12,7 @@ #define pr_fmt(fmt) "resctrl: " fmt #include +#include #include #include #include @@ -25,6 +26,7 @@ #include #include #include +#include #include #include #include @@ -327,6 +329,18 @@ static enum pmt_feature_id lookup_pfid(const char *pfname) return FEATURE_INVALID; } +/* + * Serialises AET's view of pmt_telemetry: + * - pmt_module, get_feature, put_feature + * - every event_group's ->pfg + * + * Lock ordering with pmt/telemetry.c's ep_lock is ep_lock -> aet_lock. + * AET therefore must not call get_feature() (which takes ep_lock) while + * holding aet_lock. put_feature() does not take ep_lock and may be + * invoked with aet_lock held. + */ +static DEFINE_MUTEX(aet_lock); + static struct module *pmt_module; static struct pmt_feature_group *(*get_feature)(enum pmt_feature_id id); static void (*put_feature)(struct pmt_feature_group *p); @@ -342,7 +356,8 @@ static void (*put_feature)(struct pmt_feature_group *p); * struct pmt_feature_group to indicate that its events are successfully * enabled. */ -bool intel_aet_get_events(void) +static bool aet_get_events(struct pmt_feature_group *(*get)(enum pmt_feature_id id), + void (*put)(struct pmt_feature_group *p)) { struct pmt_feature_group *p; enum pmt_feature_id pfid; @@ -351,14 +366,16 @@ bool intel_aet_get_events(void) for_each_event_group(peg) { pfid = lookup_pfid((*peg)->pfname); - p = intel_pmt_get_regions_by_feature(pfid); + p = get(pfid); if (IS_ERR_OR_NULL(p)) continue; if (enable_events(*peg, p)) { - (*peg)->pfg = p; + scoped_guard(mutex, &aet_lock) { + (*peg)->pfg = p; + } ret = true; } else { - intel_pmt_put_feature_group(p); + put(p); } } @@ -369,6 +386,7 @@ void intel_aet_register_enumeration(struct module *module, struct pmt_feature_group *(*get)(enum pmt_feature_id id), void (*put)(struct pmt_feature_group *p)) { + guard(mutex)(&aet_lock); get_feature = get; put_feature = put; pmt_module = module; @@ -377,19 +395,50 @@ EXPORT_SYMBOL_NS_GPL(intel_aet_register_enumeration, "INTEL_PMT"); void intel_aet_unregister_enumeration(void) { + guard(mutex)(&aet_lock); pmt_module = NULL; get_feature = NULL; put_feature = NULL; } EXPORT_SYMBOL_NS_GPL(intel_aet_unregister_enumeration, "INTEL_PMT"); +bool intel_aet_pre_mount(void) +{ + struct pmt_feature_group *(*get)(enum pmt_feature_id id); + void (*put)(struct pmt_feature_group *p); + struct module *mod; + + /* + * Snapshot the callbacks and pin the pmt_telemetry module under + * aet_lock. The module reference keeps pmt_telem_exit() from + * running intel_aet_unregister_enumeration() and changing these + * pointers, so the snapshot remains valid after dropping aet_lock. + */ + scoped_guard(mutex, &aet_lock) { + if (!get_feature || !put_feature) + return false; + if (!try_module_get(pmt_module)) + return false; + mod = pmt_module; + get = get_feature; + put = put_feature; + } + + if (!aet_get_events(get, put)) { + module_put(mod); + return false; + } + + return true; +} + void __exit intel_aet_exit(void) { struct event_group **peg; for_each_event_group(peg) { if ((*peg)->pfg) { - intel_pmt_put_feature_group((*peg)->pfg); + put_feature((*peg)->pfg); (*peg)->pfg = NULL; } } -- 2.56.0