From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.6]) (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 2C5D7547070 for ; Fri, 18 Sep 2026 05:01:46 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.6 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789707708; cv=none; b=pqHUtLJEYLfHA/GYDpRVVKcpsOepkVY+Q+0MUj4VKag08A0m7NgX1q4eSPNZ6GhcYSR1Vsz7830qoS8uTtUYjEH6Mf4HxJ50UfqBmp9AfqrZx525f+hsstKcIipyZ1WGbZwAIqOmyQP6PpDra/AB6F1xB1bYi6jeiAu524yGYVM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789707708; c=relaxed/simple; bh=iyhvSZKEJbUo1GxfN6urlameJ0XPTHn5O/gYeTE8UH8=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=IAi5I4yuEmjdEhFLXh+XhbSelhiaqgorPzS8q/lWIyViVYptiCRXtEvcQkAmbDd97u50aQzN3wLrw0wygO/jTPcqoDA2101fR0CfYlZpNSZr59hb9mSFEEbjgjHYqsxjt6+h9ExNmIpWeosRzTs6wFSzf8ToVY//3qWMKSu8FnY= 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=SySM41DU; arc=none smtp.client-ip=192.198.163.6 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="SySM41DU" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1789707708; x=1821243708; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=iyhvSZKEJbUo1GxfN6urlameJ0XPTHn5O/gYeTE8UH8=; b=SySM41DUqyduOABi7pSwr43gPqpOB8oIHbhP7gfGuiLeheLbyMBv2laz 4qy3LwFZ8StOXlgzl9BooBa3vXWEt8St9CTgxBofKQkDPOvf7mPBtNf/7 emTmV8PSBS0yFdmW3szEaRo291r2WuubVMan1C+94Ri03FTJbWM04OCuk /At5I7s3X9Yj/VCLz2ooD9Pjo/p0+v2hetEtgj4k3qlyGnmttIFvcjQxm qxG+P4nwAoGzPU5PfLwABDzPAbCbbXKLWl6EoItgjbK5TOP2h7yYtggHP M0fjW2uVv2OrnW8qEHGX+3pQKuadiusnhKmBM3B7HiO/+4wejXk5FD0Y7 A==; X-CSE-ConnectionGUID: 9pFfc9JXSB+m4Go5AppYbA== X-CSE-MsgGUID: hPAkl8ylTmScSzoZwZ5E0w== X-IronPort-AV: E=McAfee;i="6800,10657,11905"; a="704940" X-IronPort-AV: E=Sophos;i="6.27,103,1787036400"; d="scan'208";a="704940" Received: from fmviesa008.fm.intel.com ([10.60.135.148]) by fmvoesa116.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Sep 2026 22:01:47 -0700 X-CSE-ConnectionGUID: dWcyI+e5SvKEicdBn6QSGw== X-CSE-MsgGUID: T9xlsuNGSGSFPBYFVD72Ag== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.27,103,1787036400"; d="scan'208";a="271542646" Received: from chenyu-dev.sh.intel.com ([10.239.62.107]) by fmviesa008.fm.intel.com with ESMTP; 17 Sep 2026 22:01:43 -0700 From: Chen Yu To: tony.luck@intel.com, reinette.chatre@intel.com Cc: tglx@kernel.org, bp@alien8.de, mingo@redhat.com, dave.hansen@linux.intel.com, hpa@zytor.com, fenghuay@nvidia.com, babu.moger@amd.com, hongyu.ning@intel.com, chen.yu@linux.dev, x86@kernel.org, linux-kernel@vger.kernel.org, Chen Yu , Hongyu Ning Subject: [PATCH v8 9/9] x86/resctrl: Add MMIO-based LLC occupancy monitoring support Date: Fri, 18 Sep 2026 12:51:17 +0800 Message-Id: X-Mailer: git-send-email 2.25.1 In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Add erdt_mon_read() to read LLC occupancy via MMIO and use it when the platform supports ERDT. Register the L3 occupancy event with ERDT enabled when available, falling back to the MSR-based path otherwise. Use the CMRC (Cache Monitoring Registers for CPU Agents Description) ACPI sub-table to read LLC occupancy counters for each RMID via MMIO when ERDT is enabled. Store the CMRC information in the rdt_hw_l3_mon_domain, which could be accessed directly. Although the occupancy counters can now be read from any CPU via MMIO, the per-domain limbo handler is kept. A global handler would still have to iterate over every domain and would only save one worker thread, which does not justify maintaining two limbo handler models. Suggested-by: Reinette Chatre Signed-off-by: Chen Yu Tested-by: Hongyu Ning --- arch/x86/include/asm/resctrl.h | 8 ++- arch/x86/kernel/cpu/resctrl/core.c | 5 +- arch/x86/kernel/cpu/resctrl/erdt.c | 74 +++++++++++++++++++++++++- arch/x86/kernel/cpu/resctrl/internal.h | 9 +++- arch/x86/kernel/cpu/resctrl/monitor.c | 14 +++-- 5 files changed, 102 insertions(+), 8 deletions(-) diff --git a/arch/x86/include/asm/resctrl.h b/arch/x86/include/asm/resctrl.h index bcfcc8ac1fe6..31c2f81cd06e 100644 --- a/arch/x86/include/asm/resctrl.h +++ b/arch/x86/include/asm/resctrl.h @@ -135,7 +135,13 @@ static inline void __resctrl_sched_in(struct task_struct *tsk) static inline unsigned int resctrl_arch_round_mon_val(unsigned int val) { - unsigned int scale = boot_cpu_data.x86_cache_occ_scale; + unsigned int scale = boot_cpu_data.x86_cache_occ_scale, escale; + + if (erdt_cpu_has(X86_FEATURE_CQM_OCCUP_LLC)) { + escale = erdt_get_scale(); + if (escale) + scale = escale; + } /* h/w works in units of "boot_cpu_data.x86_cache_occ_scale" */ val /= scale; diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c index ca7e67f976d5..135f2eb2a5a5 100644 --- a/arch/x86/kernel/cpu/resctrl/core.c +++ b/arch/x86/kernel/cpu/resctrl/core.c @@ -1007,7 +1007,10 @@ static __init bool get_rdt_mon_resources(void) struct rdt_resource *r = &rdt_resources_all[RDT_RESOURCE_L3].r_resctrl; bool ret = false; - if (rdt_cpu_has(X86_FEATURE_CQM_OCCUP_LLC)) { + if (erdt_cpu_has(X86_FEATURE_CQM_OCCUP_LLC)) { + resctrl_enable_mon_event(QOS_L3_OCCUP_EVENT_ID, true, 0, NULL); + ret = true; + } else if (rdt_cpu_has(X86_FEATURE_CQM_OCCUP_LLC)) { resctrl_enable_mon_event(QOS_L3_OCCUP_EVENT_ID, false, 0, NULL); ret = true; } diff --git a/arch/x86/kernel/cpu/resctrl/erdt.c b/arch/x86/kernel/cpu/resctrl/erdt.c index 400973ebf2b8..f350a516d3d9 100644 --- a/arch/x86/kernel/cpu/resctrl/erdt.c +++ b/arch/x86/kernel/cpu/resctrl/erdt.c @@ -26,6 +26,10 @@ static bool erdt_enabled; #define CMRC_SUPPORTED_INDEX_FN 1 #define RMDD_FLAG_CPU_L3_DOMAIN BIT(0) +/* Set in a monitoring counter when it holds no valid data to report. */ +#define UNAVAILABLE_COUNTER BIT_ULL(63) +#define CMRC_FLAG_UNAVAILABLE_BIT BIT(0) + /* Bitmask of valid sub-tables found in the first RMDD, used to ensure all RMDDs match. */ static u32 valid_subtbl_mask; @@ -50,7 +54,12 @@ static unsigned int erdt_scale; bool erdt_support(int flag) { - return false; + switch (flag) { + case X86_FEATURE_CQM_OCCUP_LLC: + return valid_subtbl_mask & BIT(ACPI_ERDT_TYPE_CMRC); + default: + return false; + } } unsigned int erdt_get_max_rmid(void) @@ -60,7 +69,68 @@ unsigned int erdt_get_max_rmid(void) unsigned int erdt_get_scale(void) { - return erdt_scale; + /* Divided by snc_nodes_per_l3_cache, see erdt_read_l3_occupancy(). */ + return erdt_scale / snc_nodes_per_l3_cache; +} + +static u32 cmrc_index_function_1(struct acpi_erdt_cmrc *cmrc, u32 rmid) +{ + /* + * MMIO_offset_for_RMID# = + * (RMID / ClumpSize) * Stride + + * (RMID % ClumpSize) * 8 + */ + return (rmid / cmrc->clump_size) * cmrc->clump_stride + + (rmid % cmrc->clump_size) * 8; +} + +static int erdt_read_l3_occupancy(const struct erdt_domain_info *d, u32 rmid, u64 *val) +{ + struct acpi_erdt_cmrc *cmrc; + u64 l3_cmt_count; + u32 offset; + + cmrc = d->cmrc; + if (!cmrc) + return -EIO; + + offset = cmrc_index_function_1(cmrc, rmid); + /* Overflow of cmt_reg_size * SZ_4K already validated in erdt_ioremap(). */ + if (offset + sizeof(u64) > (u32)cmrc->cmt_reg_size * SZ_4K) + return -EINVAL; + + l3_cmt_count = readq(d->base[ERDT_MMIO_CMRC_BASE] + offset); + if ((cmrc->flags & CMRC_FLAG_UNAVAILABLE_BIT) && + (l3_cmt_count & UNAVAILABLE_COUNTER)) + return -EINVAL; + + /* + * In legacy mode, scale is divided by snc_nodes_per_l3_cache to + * prevent over-calculation of aggregated monitor data, do it + * the same for MMIO based access. + * This scaling factor might need to be revisited/tuned for future + * platforms that support both SNC and MMIO-based monitoring + * simultaneously. + */ + *val = l3_cmt_count * cmrc->up_scale / snc_nodes_per_l3_cache; + + return 0; +} + +int erdt_mon_read(struct rdt_domain_hdr *hdr, enum resctrl_event_id evtid, u32 rmid, u64 *val) +{ + struct rdt_hw_l3_mon_domain *hw_dom; + const struct erdt_domain_info *d; + + hw_dom = resctrl_to_arch_mon_dom(container_of(hdr, struct rdt_l3_mon_domain, hdr)); + d = hw_dom->d_info; + if (!d) + return -EIO; + + if (evtid == QOS_L3_OCCUP_EVENT_ID) + return erdt_read_l3_occupancy(d, rmid, val); + + return -EIO; } static void __iomem *erdt_ioremap(resource_size_t base, u32 num_pages, const char *desc) diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h index ce037e017fc3..e2d0d6c76b20 100644 --- a/arch/x86/kernel/cpu/resctrl/internal.h +++ b/arch/x86/kernel/cpu/resctrl/internal.h @@ -156,7 +156,11 @@ struct msr_param { * which has been corrected for features like CDP. * @msr_base: Base MSR address for CBMs * @msr_update: Function pointer to update QOS MSRs - * @mon_scale: cqm counter * mon_scale = occupancy in bytes + * @mon_scale: Scale factor applied to a raw counter value on the + * MSR-based read path: CMT occupancy counter * mon_scale = + * occupancy in bytes, and MBM chunk count * mon_scale = bytes + * transferred. ERDT reads occupancy via MMIO and applies its + * own firmware-provided scale instead. * @mbm_width: Monitor width, to detect and correct for overflow. * @cdp_enabled: CDP state of this resource * @mbm_cntr_assign_enabled: ABMC feature is enabled @@ -185,6 +189,8 @@ static inline struct rdt_hw_resource *resctrl_to_arch_res(struct rdt_resource *r extern struct rdt_hw_resource rdt_resources_all[]; +extern int snc_nodes_per_l3_cache; + void arch_mon_domain_online(struct rdt_resource *r, struct rdt_l3_mon_domain *d); /* CPUID.(EAX=10H, ECX=ResID=1).EAX */ @@ -289,6 +295,7 @@ static inline bool intel_handle_aet_option(bool force_off, char *tok) { return f bool erdt_support(int flag); unsigned int erdt_get_max_rmid(void); +int erdt_mon_read(struct rdt_domain_hdr *hdr, enum resctrl_event_id evtid, u32 rmid, u64 *val); int erdt_init(void); void erdt_exit(void); diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c index 138fd420131b..1fc02020dbc9 100644 --- a/arch/x86/kernel/cpu/resctrl/monitor.c +++ b/arch/x86/kernel/cpu/resctrl/monitor.c @@ -34,7 +34,7 @@ bool rdt_mon_capable; #define CF(cf) ((unsigned long)(1048576 * (cf) + 0.5)) -static int snc_nodes_per_l3_cache = 1; +int snc_nodes_per_l3_cache = 1; /* * The correction factor table is documented in Documentation/filesystems/resctrl.rst. @@ -283,6 +283,10 @@ int resctrl_arch_rmid_read(struct rdt_resource *r, struct rdt_domain_hdr *hdr, switch (r->rid) { case RDT_RESOURCE_L3: + if (eventid == QOS_L3_OCCUP_EVENT_ID && + erdt_cpu_has(X86_FEATURE_CQM_OCCUP_LLC)) + return erdt_mon_read(hdr, eventid, rmid, val); + return arch_l3_read_event(r, hdr, rmid, eventid, val); case RDT_RESOURCE_PERF_PKG: return intel_aet_read_event(hdr->id, rmid, arch_priv, val); @@ -432,12 +436,16 @@ int __init rdt_get_l3_mon_config(struct rdt_resource *r) struct rdt_hw_resource *hw_res = resctrl_to_arch_res(r); unsigned int threshold; u32 eax, ebx, ecx, edx; + int max_rmid; snc_nodes_per_l3_cache = snc_get_config(); + max_rmid = erdt_cpu_has(X86_FEATURE_CQM_OCCUP_LLC) ? + min_t(int, erdt_get_max_rmid(), boot_cpu_data.x86_cache_max_rmid) : + boot_cpu_data.x86_cache_max_rmid; resctrl_rmid_realloc_limit = boot_cpu_data.x86_cache_size * 1024; hw_res->mon_scale = boot_cpu_data.x86_cache_occ_scale / snc_nodes_per_l3_cache; - r->mon.num_rmid = (boot_cpu_data.x86_cache_max_rmid + 1) / snc_nodes_per_l3_cache; + r->mon.num_rmid = (max_rmid + 1) / snc_nodes_per_l3_cache; hw_res->mbm_width = MBM_CNTR_WIDTH_BASE; if (mbm_offset > 0 && mbm_offset <= MBM_CNTR_WIDTH_OFFSET_MAX) @@ -456,7 +464,7 @@ int __init rdt_get_l3_mon_config(struct rdt_resource *r) /* * Because num_rmid may not be a power of two, round the value - * to the nearest multiple of hw_res->mon_scale so it matches a + * to the nearest multiple of hw_res->mon_scale or mmio scale so it matches a * value the hardware will measure. mon_scale may not be a power of 2. */ resctrl_rmid_realloc_threshold = resctrl_arch_round_mon_val(threshold); -- 2.25.1