From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=192.198.163.13 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1792621337; b=2HrC00Esy+tsmcuwx5+f5UBILGPNchErRfW6HY/8rePvWa2HqMFgjdnNm8o6HoOp4sPJ pQ5wVWsAh1tDYA/EzfLDezNvLeWExK4eOSHGUQXLUAsEXR57cwYiRZBe/W6oq50idkK/P BQ+ycxvdE002VRX3/LA+TyyTcrdcc3cpOMCUPGhKF7zVzmU30UWVExemdoj0c3ZSYiwjm DS5mlLn/KBcn9mT0UrDWMh9I/W/CQt5amM5mM2CafcNqgQ/BO58nMie5kGrKMzFG8XRfh WjyPoicv17WW10Ke081zEUb8dzsjr0FKTSsTb5tRKg8i8OixpWMQ632Ki5pTDTgev+A== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1792621337; 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=xrsD24iqP9BcnJ+m4SyhgJDWqDe/xNX2cexHWZXcXLQ=; b=RM6Y3R7jxgbDmRAUH0f4R1LRie++Ug6/+/7MYsoSuoVt8Dpk8CM90I5Sh1OaWsaITvmG bOrRkqvAZMS2ACYXpn/lpDUSciePT0Mf1/8I380dY2dqCQHOKWUaYIoYH8jbb2LhFGYY0 PF8WsRiJfEtgPbw2Rj+oxT0FqhKRs+ie9TUbBzjBqowsQa63J1EeCRReTQPEsT+SggJB+ eSeCWKnsn0vE8J8jRxnBlNUWb86Nr8czv5DZDT/rqSQhrFMEN9BSfspDWwUipMN7XunZQ zv6w0Ng+qXQNh6McG+LY5s1Yc/1xc8gNPtJsq77gD4k+Yp2hPVSxJiWhSkCnlpjQcig== 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=SiicTOQ3; arc=none smtp.remote-ip=192.198.163.13 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.13]) (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 B1762606A323 for ; Wed, 21 Oct 2026 22:22:16 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org B1762606A323 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=SiicTOQ3 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1792621336; x=1824157336; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=DmYRawRuj7bsQmnCYT62WbVrUFTA/FdRxfX6js16pZo=; b=SiicTOQ3/2406TV1EYCyKoeToPz9RAE4MGkoWrRdJhCPJ8LTRTP0h95K 6evAcXt0DVkT1GjBVSih5G1HBHFSF5lqhfMhFkWkz90HKvRb4Bj4Vw0Fn cL3JLdDxz9LTGK5gLSP8g9rXfsz+NpXnKuPZ0xVOaGCIiN5BlaMhjJQD6 OhOyEXRCwSKhZYAsPmFFnpdQHdbcVPmh6/XhYkMEnK4h9aYIBAsfIOHMX W1NNvjCBjlu6u/TuRtd3hPChVkxoVjZi+ocTcZQwC8VJWqovqIhZqW7XT GUcjFZsllyV4o4kGs4MUiQ48tX9fnaQZXuA8J4AktAtyliPnYdTIwqiA/ g==; X-CSE-ConnectionGUID: a09PEcPaRcGwLvz27gdUFg== X-CSE-MsgGUID: FTj2iqAxR4SDTBhXRUrGrg== X-IronPort-AV: E=McAfee;i="6800,10657,11942"; a="1346499" X-IronPort-AV: E=Sophos;i="6.27,171,1787036400"; d="scan'208";a="1346499" Received: from orviesa003.jf.intel.com ([10.64.159.143]) by fmvoesa107.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 21 Oct 2026 15:22:16 -0700 X-CSE-ConnectionGUID: PoABvuNHT06unKb5OzN5Pw== X-CSE-MsgGUID: FYhdS9y+T8KwCY5iIXyMwQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.27,171,1787036400"; d="scan'208";a="3127900" Received: from rodrigoa-mobl1.amr.corp.intel.com (HELO agluck-desk3.intel.com) ([10.124.220.213]) by smtpauth.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 21 Oct 2026 15:22:16 -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+ 20/24] x86/resctrl: Export interface to report telemetry unbind/remove Date: Wed, 21 Oct 2026 15:22:08 -0700 Message-ID: <20261021222208.16324-1-tony.luck@intel.com> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261019205031.16977-21-tony.luck@intel.com> References: <20261019205031.16977-21-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 obtains the addresses of the telemetry MMIO regions from the pmt_telemetry driver at mount time and holds a reference on the module until unmount, so the module cannot be unloaded while resctrl may read the counters. The module reference does not prevent a telemetry device from being unbound from the driver, or removed. Either tears down the MMIO mappings that hold the event counters, and a subsequent read of an event by resctrl faults on the stale address. Provide an interface for pmt_telemetry to report that the mappings for a package are about to be torn down. Stop using the regions of that package and serialize event reads with the notification so that no read uses an address once it has been reported. Events of the affected package then read "Unavailable". Update AET enumeration to handle races between enumeration and device unbind/removal. Count invalidations in a generation counter protected by aet_lock. Sample it before calling get_feature() and, under aet_lock, check that it did not change before enabling events and publishing the copy. If it changed, drop the copy and retry. The new copy reflects the removal. Signed-off-by: Tony Luck --- v14+ Handle races between enumeration and device unbind/remove by adding a count of invalidations that is updated & checked while holding aet_lock. include/linux/intel_vsec.h | 2 + arch/x86/kernel/cpu/resctrl/intel_aet.c | 87 ++++++++++++++++++++++--- 2 files changed, 80 insertions(+), 9 deletions(-) diff --git a/include/linux/intel_vsec.h b/include/linux/intel_vsec.h index c04b1d0f3143..bcbf4937c71c 100644 --- a/include/linux/intel_vsec.h +++ b/include/linux/intel_vsec.h @@ -262,11 +262,13 @@ 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)); void intel_aet_unregister_enumeration(void); +void intel_aet_invalidate(u8 package_id); #else static inline 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)) { } static inline void intel_aet_unregister_enumeration(void) { } +static inline void intel_aet_invalidate(u8 package_id) { } #endif /* CONFIG_X86_CPU_RESCTRL_INTEL_AET */ #endif diff --git a/arch/x86/kernel/cpu/resctrl/intel_aet.c b/arch/x86/kernel/cpu/resctrl/intel_aet.c index 4ba27586fb50..589666e12b78 100644 --- a/arch/x86/kernel/cpu/resctrl/intel_aet.c +++ b/arch/x86/kernel/cpu/resctrl/intel_aet.c @@ -339,6 +339,8 @@ static enum pmt_feature_id lookup_pfid(const char *pfname) * Serialises AET's view of pmt_telemetry: * - pmt_module, get_feature, put_feature, pmt_in_use * - every event_group's ->pfg + * - the telemetry_region::addr entries reachable through ->pfg + * - aet_invalidate_gen * * 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 @@ -356,6 +358,30 @@ static void (*put_feature)(struct pmt_feature_group *p); */ static bool pmt_in_use; +/* + * Detect MMIO invalidations to resolve races between device unbind/remove + * and mount or resctrl file system. + */ +static unsigned int aet_invalidate_gen; + +/* + * Confirm that no MMIO invalidations occured before adding the feature + * group to the event group. + */ +static int aet_publish_events(struct event_group *e, struct pmt_feature_group *p, + unsigned int gen) +{ + guard(mutex)(&aet_lock); + + if (gen != aet_invalidate_gen) + return -EAGAIN; + if (!enable_events(e, p)) + return -ENODEV; + e->pfg = p; + + return 0; +} + /* * Request a copy of struct pmt_feature_group for each event group. If there is * one, the returned structure has an array of telemetry_region structures, @@ -373,24 +399,36 @@ static bool aet_get_events(struct pmt_feature_group *(*get)(enum pmt_feature_id struct pmt_feature_group *p; enum pmt_feature_id pfid; struct event_group **peg; + unsigned int gen; bool ret = false; + int err; if (!resctrl_arch_system_max_rmid_idx()) return false; for_each_event_group(peg) { pfid = lookup_pfid((*peg)->pfname); - p = get(pfid); - if (IS_ERR_OR_NULL(p)) - continue; - if (enable_events(*peg, p)) { - scoped_guard(mutex, &aet_lock) { - (*peg)->pfg = p; + do { + /* + * get() takes ep_lock, so it cannot be called with + * aet_lock held. Sample the invalidation generation + * first and retry if a telemetry device was removed + * before @p could be published. + */ + scoped_guard(mutex, &aet_lock) + gen = aet_invalidate_gen; + p = get(pfid); + if (IS_ERR_OR_NULL(p)) { + err = -ENOENT; + break; } + err = aet_publish_events(*peg, p, gen); + if (err) + put(p); + } while (err == -EAGAIN); + + if (!err) ret = true; - } else { - put(p); - } } return ret; @@ -416,6 +454,35 @@ void intel_aet_unregister_enumeration(void) } EXPORT_SYMBOL_NS_GPL(intel_aet_unregister_enumeration, "INTEL_PMT"); +/* + * pmt_telemetry driver calls while holding ep_lock. This is for unbind/remove + * operations that will invalidate the virtual addresses of MMIO registers + * provided by intel_pmt_get_regions_by_feature(). This simple interface may + * be overly broad if there are multiple telemetry devices per-package. An + * unbind/remove operation on one device will stop resctrl from reading + * event counters from all devices on the same package. + */ +void intel_aet_invalidate(u8 package_id) +{ + struct event_group **peg; + + guard(mutex)(&aet_lock); + + aet_invalidate_gen++; + + for_each_event_group(peg) { + struct event_group *e = *peg; + + if (!e->pfg) + continue; + for (int i = 0; i < e->pfg->count; i++) { + if (e->pfg->regions[i].plat_info.package_id == package_id) + e->pfg->regions[i].addr = NULL; + } + } +} +EXPORT_SYMBOL_NS_GPL(intel_aet_invalidate, "INTEL_PMT"); + bool intel_aet_pre_mount(void) { struct pmt_feature_group *(*get)(enum pmt_feature_id id); @@ -491,6 +558,8 @@ int intel_aet_read_event(int domid, u32 rmid, void *arch_priv, u64 *val) void *pevt0; u32 idx; + guard(mutex)(&aet_lock); + pevt0 = pevt - pevt->idx; e = container_of(pevt0, struct event_group, evts); idx = rmid * e->num_events; -- 2.56.0