From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-17.0 required=3.0 tests=BAYES_00,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D2B66C433EF for ; Fri, 10 Sep 2021 18:57:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B457F611EE for ; Fri, 10 Sep 2021 18:57:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232542AbhIJS6o (ORCPT ); Fri, 10 Sep 2021 14:58:44 -0400 Received: from mail-wm1-f54.google.com ([209.85.128.54]:41855 "EHLO mail-wm1-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229476AbhIJS6b (ORCPT ); Fri, 10 Sep 2021 14:58:31 -0400 Received: by mail-wm1-f54.google.com with SMTP id u15-20020a05600c19cf00b002f6445b8f55so2054540wmq.0; Fri, 10 Sep 2021 11:57:19 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=13EDgotJZ+G06ORiWEpef1AccnsPNuViikUMH2ucpYI=; b=NWxY21BCQedoj1DTknmeqO4nx/eoBRMdmNE6dwiKS3SNlNHtfKcDNLflrR8u1+1Uqa DGark6sPB7FeIFs7/QoWsd4KfodzXN6MC4b3FgN3DnbPFTL/effxty9lcT4m8MaQtAjb eOkc6oHj3+20/v2Oy4s9khRJcSmwPx20z9I6dlr8B7xydQZO01Ygw++0yWuFouztLVUL kgzV8Te50nniFMpw7IqTQKnnrFl4EJgmTmG0f9IKT4jxtKKedtMu6VRZepP/M5UQTrPg mEQi+W9XTz770SyjpPsuS6SLALMDBqZkwtcPwyp9NEQMHEJ1AhEiktn35KntQBKOfOYw eq2g== X-Gm-Message-State: AOAM530VzCZRNA2FhDvEGnqg0+PLsXQIzetVm+9Bw4/KpelC+rJuj7iG 1j6F29lVi99TdinLfWzZtzqcBKaUnis= X-Google-Smtp-Source: ABdhPJw57slBfic7WbKKqf8UnXEcz1SwjB98725fe4ScvL8LAdWM/jtezySQIF8KoYMlaFlgG5Xayg== X-Received: by 2002:a1c:a911:: with SMTP id s17mr9103269wme.84.1631300238959; Fri, 10 Sep 2021 11:57:18 -0700 (PDT) Received: from liuwe-devbox-debian-v2.j3c5onc20sse1dnehy4noqpfcg.zx.internal.cloudapp.net ([51.145.34.42]) by smtp.gmail.com with ESMTPSA id y4sm5015351wmi.22.2021.09.10.11.57.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 10 Sep 2021 11:57:18 -0700 (PDT) From: Wei Liu To: Linux on Hyper-V List Cc: Michael Kelley , kys@microsoft.com, haiyangz@microsoft.com, decui@microsoft.com, sthemmin@microsoft.com, Wei Liu , Linus Torvalds , Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org (maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)), "H. Peter Anvin" , linux-kernel@vger.kernel.org (open list:X86 ARCHITECTURE (32-BIT AND 64-BIT)) Subject: [PATCH v2 2/2] x86/hyperv: remove on-stack cpumask from hv_send_ipi_mask_allbutself Date: Fri, 10 Sep 2021 18:57:14 +0000 Message-Id: <20210910185714.299411-3-wei.liu@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210910185714.299411-1-wei.liu@kernel.org> References: <20210910185714.299411-1-wei.liu@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org It is not a good practice to allocate a cpumask on stack, given it may consume up to 1 kilobytes of stack space if the kernel is configured to have 8192 cpus. The internal helper functions __send_ipi_mask{,_ex} need to loop over the provided mask anyway, so it is not too difficult to skip `self' there. We can thus do away with the on-stack cpumask in hv_send_ipi_mask_allbutself. Adjust call sites of __send_ipi_mask as needed. Reported-by: Linus Torvalds Suggested-by: Michael Kelley Suggested-by: Linus Torvalds Fixes: 68bb7bfb7985d ("X86/Hyper-V: Enable IPI enlightenments") Signed-off-by: Wei Liu --- v2: more robust check in __send_ipi_mask --- arch/x86/hyperv/hv_apic.c | 43 +++++++++++++++++++++++---------------- 1 file changed, 26 insertions(+), 17 deletions(-) diff --git a/arch/x86/hyperv/hv_apic.c b/arch/x86/hyperv/hv_apic.c index 90e682a92820..48aefcea724b 100644 --- a/arch/x86/hyperv/hv_apic.c +++ b/arch/x86/hyperv/hv_apic.c @@ -99,7 +99,8 @@ static void hv_apic_eoi_write(u32 reg, u32 val) /* * IPI implementation on Hyper-V. */ -static bool __send_ipi_mask_ex(const struct cpumask *mask, int vector) +static bool __send_ipi_mask_ex(const struct cpumask *mask, int vector, + bool exclude_self) { struct hv_send_ipi_ex **arg; struct hv_send_ipi_ex *ipi_arg; @@ -123,7 +124,10 @@ static bool __send_ipi_mask_ex(const struct cpumask *mask, int vector) if (!cpumask_equal(mask, cpu_present_mask)) { ipi_arg->vp_set.format = HV_GENERIC_SET_SPARSE_4K; - nr_bank = cpumask_to_vpset(&(ipi_arg->vp_set), mask); + if (exclude_self) + nr_bank = cpumask_to_vpset_noself(&(ipi_arg->vp_set), mask); + else + nr_bank = cpumask_to_vpset(&(ipi_arg->vp_set), mask); } if (nr_bank < 0) goto ipi_mask_ex_done; @@ -138,15 +142,25 @@ static bool __send_ipi_mask_ex(const struct cpumask *mask, int vector) return hv_result_success(status); } -static bool __send_ipi_mask(const struct cpumask *mask, int vector) +static bool __send_ipi_mask(const struct cpumask *mask, int vector, + bool exclude_self) { - int cur_cpu, vcpu; + int cur_cpu, vcpu, this_cpu = smp_processor_id(); struct hv_send_ipi ipi_arg; u64 status; + unsigned int weight; trace_hyperv_send_ipi_mask(mask, vector); - if (cpumask_empty(mask)) + weight = cpumask_weight(mask); + + /* + * Do nothing if + * 1. the mask is empty + * 2. the mask only contains self when exclude_self is true + */ + if (weight == 0 || + (exclude_self && weight == 1 && cpumask_first(mask) == this_cpu)) return true; if (!hv_hypercall_pg) @@ -172,6 +186,8 @@ static bool __send_ipi_mask(const struct cpumask *mask, int vector) ipi_arg.cpu_mask = 0; for_each_cpu(cur_cpu, mask) { + if (exclude_self && cur_cpu == this_cpu) + continue; vcpu = hv_cpu_number_to_vp_number(cur_cpu); if (vcpu == VP_INVAL) return false; @@ -191,7 +207,7 @@ static bool __send_ipi_mask(const struct cpumask *mask, int vector) return hv_result_success(status); do_ex_hypercall: - return __send_ipi_mask_ex(mask, vector); + return __send_ipi_mask_ex(mask, vector, exclude_self); } static bool __send_ipi_one(int cpu, int vector) @@ -208,7 +224,7 @@ static bool __send_ipi_one(int cpu, int vector) return false; if (vp >= 64) - return __send_ipi_mask_ex(cpumask_of(cpu), vector); + return __send_ipi_mask_ex(cpumask_of(cpu), vector, false); status = hv_do_fast_hypercall16(HVCALL_SEND_IPI, vector, BIT_ULL(vp)); return hv_result_success(status); @@ -222,20 +238,13 @@ static void hv_send_ipi(int cpu, int vector) static void hv_send_ipi_mask(const struct cpumask *mask, int vector) { - if (!__send_ipi_mask(mask, vector)) + if (!__send_ipi_mask(mask, vector, false)) orig_apic.send_IPI_mask(mask, vector); } static void hv_send_ipi_mask_allbutself(const struct cpumask *mask, int vector) { - unsigned int this_cpu = smp_processor_id(); - struct cpumask new_mask; - const struct cpumask *local_mask; - - cpumask_copy(&new_mask, mask); - cpumask_clear_cpu(this_cpu, &new_mask); - local_mask = &new_mask; - if (!__send_ipi_mask(local_mask, vector)) + if (!__send_ipi_mask(mask, vector, true)) orig_apic.send_IPI_mask_allbutself(mask, vector); } @@ -246,7 +255,7 @@ static void hv_send_ipi_allbutself(int vector) static void hv_send_ipi_all(int vector) { - if (!__send_ipi_mask(cpu_online_mask, vector)) + if (!__send_ipi_mask(cpu_online_mask, vector, false)) orig_apic.send_IPI_all(vector); } -- 2.30.2