From patchwork Thu Mar 16 22:20:58 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Usama Arif X-Patchwork-Id: 13178348 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id BE199C6FD1F for ; Thu, 16 Mar 2023 22:21:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230029AbjCPWVS (ORCPT ); Thu, 16 Mar 2023 18:21:18 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60640 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229532AbjCPWVR (ORCPT ); Thu, 16 Mar 2023 18:21:17 -0400 Received: from mail-wr1-x429.google.com (mail-wr1-x429.google.com [IPv6:2a00:1450:4864:20::429]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AEE3047419 for ; Thu, 16 Mar 2023 15:21:14 -0700 (PDT) Received: by mail-wr1-x429.google.com with SMTP id i9so2875395wrp.3 for ; Thu, 16 Mar 2023 15:21:14 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance.com; s=google; t=1679005273; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=mbhas2uqRPBmSN9AHCLEH2K+C2q38zTMyGQqhw7QwxQ=; b=G887ySyTaFh7l9kGNOaV9CvLHAce3lWKFnKxqTdjw2vofQU38EOn5pnpjDsI0yDU6v SUwTkKq2r0LiBMG6w1SJHI7HzH2lnEriAHZ9LCL4jhHJ3opc8byF8aic/zk1LaILitSv mJYhzqlQq2CGWJKxnIPRCO1FHG+jDQ3iJR7+D2QJbtAxzs4Fe0/RuVECwISJEfCKAM1e hezGoZjpOwomLa5loLdWbo2bv0RUqVPJ4UgkVz2hg8RJEvrSXK+1x1fWOM/CaRIYeGiB WxHdcQixkuUtJi095NoYhlgeVVYfctKmKJuECCDkQ+6qFHIhn9Py1fRO/tm/mmjRfo81 qyIA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1679005273; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=mbhas2uqRPBmSN9AHCLEH2K+C2q38zTMyGQqhw7QwxQ=; b=cyOy6+xJCEKYXx/Mv/akhGQ4p/UsG2SnNSiwMkSlqXmKt2kBpbJDp2CeEUWi0NlO7g XNOKIzb7RAj3Hwo93bQxPFC9dBzA5WXWw4KNLkVsUpk0QNzAtD/PQ9kPJCtqYJeRbPf3 Rb6yinEaU894x1KHWM3nYYSAoIsh818QGZ2JHzzZLraScLbtMjGk3PILFKP5Cxq9I8e4 RQ5SMQ6sJByjRPuVclq8ZbrkIgGIDx9GkmsLP9tkoMPr6uH23IvI+kQw9OulJCW1bCSZ fm9vcdE68U1pmIdY029o7KKjW7aVC6voeUXMtS+rN8XZJ3SZxGAO8Vl25Du+pEYZUPjy dOJw== X-Gm-Message-State: AO0yUKUjCxv7TpbV97keOoBTA3PdaOIb5w6HUz6W1RT2EdiVNx7U00zU Z/RkW8o258VHyR143xQCHnTT3g== X-Google-Smtp-Source: AK7set+bMTZLmukgrW2A62C4qRzo48IitsiiIvCeTnGqwl1t678duZeubMPmpzEWdXjl82xJDx8FbA== X-Received: by 2002:adf:e541:0:b0:2ce:3ae0:55a7 with SMTP id z1-20020adfe541000000b002ce3ae055a7mr5357953wrm.29.1679005273108; Thu, 16 Mar 2023 15:21:13 -0700 (PDT) Received: from usaari01.cust.communityfibre.co.uk ([2a02:6b6a:b566:0:4b87:78c3:3abe:7b0d]) by smtp.gmail.com with ESMTPSA id f9-20020adff989000000b002cea392f000sm439256wrr.69.2023.03.16.15.21.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 16 Mar 2023 15:21:12 -0700 (PDT) From: Usama Arif To: dwmw2@infradead.org, tglx@linutronix.de, kim.phillips@amd.com, brgerst@gmail.com Cc: piotrgorski@cachyos.org, oleksandr@natalenko.name, arjan@linux.intel.com, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com, x86@kernel.org, pbonzini@redhat.com, paulmck@kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, rcu@vger.kernel.org, mimoja@mimoja.de, hewenliang4@huawei.com, thomas.lendacky@amd.com, seanjc@google.com, pmenzel@molgen.mpg.de, fam.zheng@bytedance.com, punit.agrawal@bytedance.com, simon.evans@bytedance.com, liangma@liangbit.com, gpiccoli@igalia.com, David Woodhouse , Usama Arif Subject: [PATCH v15 01/12] x86/apic/x2apic: Allow CPU cluster_mask to be populated in parallel Date: Thu, 16 Mar 2023 22:20:58 +0000 Message-Id: <20230316222109.1940300-2-usama.arif@bytedance.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20230316222109.1940300-1-usama.arif@bytedance.com> References: <20230316222109.1940300-1-usama.arif@bytedance.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org From: David Woodhouse Each of the sibling CPUs in a cluster uses the same clustermask. The first CPU in a cluster will need a new clustermask allocated, while subsequent siblings will use the same clustermask as the first. However, the CPU being brought up cannot yet perform memory allocations at the point that this occurs in init_x2apic_ldr(). So at present, the alloc_clustermask() function allocates a clustermask just in case it's needed, storing it in the global cluster_hotplug_mask. A CPU which is the first sibling of a cluster will "take" it from there and set cluster_hotplug_mask to NULL, in order for alloc_clustermask() to allocate a new one before bringing up the next CPU. To facilitate parallel bringup of CPUs in future, switch to a model where alloc_clustermask() prepopulates the clustermask in the per_cpu data for each present CPU in the cluster in advance. All that the CPU needs to do for itself in init_x2apic_ldr() is set its own bit in that mask. The 'node' and 'clusterid' members of struct cluster_mask are thus redundant, and it can become a simple struct cpumask instead. Suggested-by: Thomas Gleixner Signed-off-by: David Woodhouse Signed-off-by: Usama Arif Tested-by: Paul E. McKenney Tested-by: Kim Phillips Tested-by: Oleksandr Natalenko Tested-by: Guilherme G. Piccoli --- arch/x86/kernel/apic/x2apic_cluster.c | 126 +++++++++++++++++--------- 1 file changed, 82 insertions(+), 44 deletions(-) diff --git a/arch/x86/kernel/apic/x2apic_cluster.c b/arch/x86/kernel/apic/x2apic_cluster.c index e696e22d0531..b2b2b7f3e03f 100644 --- a/arch/x86/kernel/apic/x2apic_cluster.c +++ b/arch/x86/kernel/apic/x2apic_cluster.c @@ -9,11 +9,7 @@ #include "local.h" -struct cluster_mask { - unsigned int clusterid; - int node; - struct cpumask mask; -}; +#define apic_cluster(apicid) ((apicid) >> 4) /* * __x2apic_send_IPI_mask() possibly needs to read @@ -23,8 +19,7 @@ struct cluster_mask { static u32 *x86_cpu_to_logical_apicid __read_mostly; static DEFINE_PER_CPU(cpumask_var_t, ipi_mask); -static DEFINE_PER_CPU_READ_MOSTLY(struct cluster_mask *, cluster_masks); -static struct cluster_mask *cluster_hotplug_mask; +static DEFINE_PER_CPU_READ_MOSTLY(struct cpumask *, cluster_masks); static int x2apic_acpi_madt_oem_check(char *oem_id, char *oem_table_id) { @@ -60,10 +55,10 @@ __x2apic_send_IPI_mask(const struct cpumask *mask, int vector, int apic_dest) /* Collapse cpus in a cluster so a single IPI per cluster is sent */ for_each_cpu(cpu, tmpmsk) { - struct cluster_mask *cmsk = per_cpu(cluster_masks, cpu); + struct cpumask *cmsk = per_cpu(cluster_masks, cpu); dest = 0; - for_each_cpu_and(clustercpu, tmpmsk, &cmsk->mask) + for_each_cpu_and(clustercpu, tmpmsk, cmsk) dest |= x86_cpu_to_logical_apicid[clustercpu]; if (!dest) @@ -71,7 +66,7 @@ __x2apic_send_IPI_mask(const struct cpumask *mask, int vector, int apic_dest) __x2apic_send_IPI_dest(dest, vector, APIC_DEST_LOGICAL); /* Remove cluster CPUs from tmpmask */ - cpumask_andnot(tmpmsk, tmpmsk, &cmsk->mask); + cpumask_andnot(tmpmsk, tmpmsk, cmsk); } local_irq_restore(flags); @@ -105,55 +100,98 @@ static u32 x2apic_calc_apicid(unsigned int cpu) static void init_x2apic_ldr(void) { - struct cluster_mask *cmsk = this_cpu_read(cluster_masks); - u32 cluster, apicid = apic_read(APIC_LDR); - unsigned int cpu; + struct cpumask *cmsk = this_cpu_read(cluster_masks); - x86_cpu_to_logical_apicid[smp_processor_id()] = apicid; + BUG_ON(!cmsk); - if (cmsk) - goto update; - - cluster = apicid >> 16; - for_each_online_cpu(cpu) { - cmsk = per_cpu(cluster_masks, cpu); - /* Matching cluster found. Link and update it. */ - if (cmsk && cmsk->clusterid == cluster) - goto update; + cpumask_set_cpu(smp_processor_id(), cmsk); +} + +/* + * As an optimisation during boot, set the cluster_mask for all present + * CPUs at once, to prevent each of them having to iterate over the others + * to find the existing cluster_mask. + */ +static void prefill_clustermask(struct cpumask *cmsk, unsigned int cpu, u32 cluster) +{ + int cpu_i; + + for_each_present_cpu(cpu_i) { + struct cpumask **cpu_cmsk = &per_cpu(cluster_masks, cpu_i); + u32 apicid = apic->cpu_present_to_apicid(cpu_i); + + if (apicid == BAD_APICID || cpu_i == cpu || apic_cluster(apicid) != cluster) + continue; + + if (WARN_ON_ONCE(*cpu_cmsk == cmsk)) + continue; + + BUG_ON(*cpu_cmsk); + *cpu_cmsk = cmsk; } - cmsk = cluster_hotplug_mask; - cmsk->clusterid = cluster; - cluster_hotplug_mask = NULL; -update: - this_cpu_write(cluster_masks, cmsk); - cpumask_set_cpu(smp_processor_id(), &cmsk->mask); } -static int alloc_clustermask(unsigned int cpu, int node) +static int alloc_clustermask(unsigned int cpu, u32 cluster, int node) { + struct cpumask *cmsk = NULL; + unsigned int cpu_i; + + /* + * At boot time, the CPU present mask is stable. The cluster mask is + * allocated for the first CPU in the cluster and propagated to all + * present siblings in the cluster. If the cluster mask is already set + * on entry to this function for a given CPU, there is nothing to do. + */ if (per_cpu(cluster_masks, cpu)) return 0; + + if (system_state < SYSTEM_RUNNING) + goto alloc; + /* - * If a hotplug spare mask exists, check whether it's on the right - * node. If not, free it and allocate a new one. + * On post boot hotplug for a CPU which was not present at boot time, + * iterate over all possible CPUs (even those which are not present + * any more) to find any existing cluster mask. */ - if (cluster_hotplug_mask) { - if (cluster_hotplug_mask->node == node) - return 0; - kfree(cluster_hotplug_mask); + for_each_possible_cpu(cpu_i) { + u32 apicid = apic->cpu_present_to_apicid(cpu_i); + + if (apicid != BAD_APICID && apic_cluster(apicid) == cluster) { + cmsk = per_cpu(cluster_masks, cpu_i); + /* + * If the cluster is already initialized, just store + * the mask and return. There's no need to propagate. + */ + if (cmsk) { + per_cpu(cluster_masks, cpu) = cmsk; + return 0; + } + } } - - cluster_hotplug_mask = kzalloc_node(sizeof(*cluster_hotplug_mask), - GFP_KERNEL, node); - if (!cluster_hotplug_mask) + /* + * No CPU in the cluster has ever been initialized, so fall through to + * the boot time code which will also populate the cluster mask for any + * other CPU in the cluster which is (now) present. + */ +alloc: + cmsk = kzalloc_node(sizeof(*cmsk), GFP_KERNEL, node); + if (!cmsk) return -ENOMEM; - cluster_hotplug_mask->node = node; + per_cpu(cluster_masks, cpu) = cmsk; + prefill_clustermask(cmsk, cpu, cluster); + return 0; } static int x2apic_prepare_cpu(unsigned int cpu) { - if (alloc_clustermask(cpu, cpu_to_node(cpu)) < 0) + u32 phys_apicid = apic->cpu_present_to_apicid(cpu); + u32 cluster = apic_cluster(phys_apicid); + u32 logical_apicid = (cluster << 16) | (1 << (phys_apicid & 0xf)); + + x86_cpu_to_logical_apicid[cpu] = logical_apicid; + + if (alloc_clustermask(cpu, cluster, cpu_to_node(cpu)) < 0) return -ENOMEM; if (!zalloc_cpumask_var(&per_cpu(ipi_mask, cpu), GFP_KERNEL)) return -ENOMEM; @@ -162,10 +200,10 @@ static int x2apic_prepare_cpu(unsigned int cpu) static int x2apic_dead_cpu(unsigned int dead_cpu) { - struct cluster_mask *cmsk = per_cpu(cluster_masks, dead_cpu); + struct cpumask *cmsk = per_cpu(cluster_masks, dead_cpu); if (cmsk) - cpumask_clear_cpu(dead_cpu, &cmsk->mask); + cpumask_clear_cpu(dead_cpu, cmsk); free_cpumask_var(per_cpu(ipi_mask, dead_cpu)); return 0; }