From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.20]) (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 C92853D9027 for ; Tue, 29 Sep 2026 17:52:31 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.20 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790704354; cv=none; b=E/uXQEffJeTW9NLF8tIIoWHcJS5EGtq7c+EB4wEoEBS3QRtEP1xYYzs6qx0Ayp74TfVqbaTEU2SnLVEgwtdRKQuTc+UynTSedH5/41rIngIlYaqbfR4Li6Yprq57BWwNF4K7bJgp2r0slDlK2AIdhqEBHOF9S4dzsSrCA3pEr3s= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790704354; c=relaxed/simple; bh=j1Z5bfCxqQ914Rixqv/n9+8vAenQaHc/PM2jNbZaxy0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=AmhFpfg8QohWAozfe+mC/ZVT9v6G+NOBFVmOgkzw4+LR1oBrkWGaHujIw1Y/Ir4bblivz2gWj03zpqyXpYLVT2SRgKejmYdtKGQF8gMHcJoafuK6DX+/tX+NwbHlDyGBBQ6wvym6K7qq3uhmi4KZm0/fPLhZuu6n3LJmvquHOUU= 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=RSKoUOzC; arc=none smtp.client-ip=198.175.65.20 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="RSKoUOzC" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1790704352; x=1822240352; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=j1Z5bfCxqQ914Rixqv/n9+8vAenQaHc/PM2jNbZaxy0=; b=RSKoUOzCZf+WVsDqJ/CNz+uTp8ajcNz2oLtShdn3sHYS86cnbSsD+79t BrqGyFUzjk+zXZdgxELWuN+IhrIDzpG1RsmHFwUyX+8WxHFjot+Pnmrpu AJkpyijyBlLiTZG9LBDRc1MIOY+SHggWUT5QLFMmC0rV3IcJ5veso0+h5 rKDdY7lV1AYFv8U/B63MSoPW39t9/mHsEvkGcQ8qSd7MizqXHdonI2q/t O4TYk6FxTgXGjDYggCB+cvh3SETk03F4MGIzhERGkprlOsb5dM94tDgQN kt5Y+bxog6eS0IfpEK96rzt5qdU3/stQExG5GGuR1CyXa5pDY6LZNjUbk g==; X-CSE-ConnectionGUID: qmZKrugwRcizc1O73AciOg== X-CSE-MsgGUID: F+nZxbb6RqmtrZH9rTm6fw== X-IronPort-AV: E=McAfee;i="6800,10657,11920"; a="90198055" X-IronPort-AV: E=Sophos;i="6.27,130,1787036400"; d="scan'208";a="90198055" Received: from orviesa008.jf.intel.com ([10.64.159.148]) by orvoesa112.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Sep 2026 10:52:31 -0700 X-CSE-ConnectionGUID: 3IHIoIpaQk2J/KjSeizPvQ== X-CSE-MsgGUID: grBByMTfQxaVhI9nr17OCw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.27,130,1787036400"; d="scan'208";a="274542425" Received: from aschofie-mobl2.amr.corp.intel.com (HELO agluck-desk3.home.arpa) ([10.124.222.232]) by orviesa008-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Sep 2026 10:52:31 -0700 From: Tony Luck To: tony.luck@intel.com Cc: Dave.Martin@arm.com, babu.moger@amd.com, david.e.box@intel.com, dfustini@baylibre.com, fenghuay@nvidia.com, hch@infradead.org, james.morse@arm.com, linux-kernel@vger.kernel.org, maciej.wieczor-retman@intel.com, patches@lists.linux.dev, peternewman@google.com, reinette.chatre@intel.com, x86@kernel.org, yu.c.chen@intel.com Subject: [PATCH v14.1 18/25] x86/resctrl: Use registered function pointers for AET enumeration Date: Tue, 29 Sep 2026 10:52:24 -0700 Message-ID: <20260929175224.16565-1-tony.luck@intel.com> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260928221509.68002-19-tony.luck@intel.com> References: <20260928221509.68002-19-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 The pmt_telemetry driver registers enumeration functions with resctrl Application Energy Telemetry (AET) code. Use the function pointers instead of direct function calls in preparation for the telemetry driver to be a loadable module. The pmt_telemetry is forced to be built-in to the kernel, so it does not matter at this point that there is no matching module_put() for the try_module_get() in intel_aet_pre_mount(). This must be resolved with additions in the file system unmount path before pmt_telemetry can be configured 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. --- 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 6c4f0bf3b876..d79c459f4c54 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 @@ -293,6 +295,18 @@ 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); @@ -308,7 +322,8 @@ 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; @@ -317,14 +332,16 @@ 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); } } @@ -335,6 +352,7 @@ 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; @@ -343,19 +361,50 @@ 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; } } -- 2.55.0