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=-8.9 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham 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 9CE91C04AB3 for ; Mon, 27 May 2019 10:34:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 69137208CA for ; Mon, 27 May 2019 10:34:25 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="ISntIzPR" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726941AbfE0KeY (ORCPT ); Mon, 27 May 2019 06:34:24 -0400 Received: from mail-pf1-f195.google.com ([209.85.210.195]:39418 "EHLO mail-pf1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725858AbfE0KeX (ORCPT ); Mon, 27 May 2019 06:34:23 -0400 Received: by mail-pf1-f195.google.com with SMTP id z26so9365204pfg.6; Mon, 27 May 2019 03:34:22 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=vBM+WK9qA4pZcm6B2byvLBaRkxAGft4URtktgvLLdCc=; b=ISntIzPRhi1novfNIUIoq8j4mN3/8DjvUbUpkbo09pCTHdRBsUziP2PIUoRUtdXVCT kV2GdCD2b4tGohQ4Hty1tJnpywXMVAQ7yXi2za+wVKfsyCa7n78KQH1un7E8DNHfjQDJ IuCjpcv2SMnFnTQ/qyPuS9tx4SOwLBfQhOQfOgRFXPUwlD94yVoWIMFG9y9d4awV07dB qdKNyLpFVbLlwLr3L1F3k5kBpVLAjHZL6N7+6JrU+PLRmOP3Coa4iqCjjE8j+bVptLlw Vw+cJxEpBhGphWPMfWAmYA6zgz55Z7bZMFnRYAlt42ANxmdDbSeeaKfmfQnQLa7FgeiL Uz1w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=vBM+WK9qA4pZcm6B2byvLBaRkxAGft4URtktgvLLdCc=; b=tiUfTn/WJ8DNRSxnPaHN++7/N68LV4Oj5lbOKdCIM2oSPoOw4zx6d4/NjaCOKsL1zD FWMcpycg/C2X4wPIHpAN8Hwk1W4ZpmvWrgA6C8aqr9jPXHrRmG3cD2pl7m89wtGObEVK KpPJPL6EW/XXOEHfkGDeAb0vEnbqn2NCrJRxsItW6QtiK2G1+bRjn5xmWddkdhYp54p2 PGUuWAbPCvl8CxjT355HFLcD8/CMGMjD1IpQWReufDsWoTEdDd2H127FYZaVNmnOrW8L /VuiJRccshe4AsUQob9TgCsnF90pi3ouDjfR0hziuQDYCtglIAgDTZNNLHVe0w14UT+M mG5g== X-Gm-Message-State: APjAAAWtHxkz1dPCdxZzCjynA91p9TZT1i8ud6XVUofvIIwjZJ03fXFU YlDvrLZ3vk81hf+6epIcMrYAGzD2 X-Google-Smtp-Source: APXvYqznobAQK1C+wXpTTAo3yaYzYHyj5rAO9BM24BpvbLoj75xMi2luo3Vo5AAi4SZCeV/ga+cmFA== X-Received: by 2002:a65:448a:: with SMTP id l10mr8005875pgq.53.1558953262208; Mon, 27 May 2019 03:34:22 -0700 (PDT) Received: from localhost.localdomain ([203.205.141.123]) by smtp.googlemail.com with ESMTPSA id y16sm19216452pfo.133.2019.05.27.03.34.20 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Mon, 27 May 2019 03:34:21 -0700 (PDT) From: Wanpeng Li X-Google-Original-From: Wanpeng Li To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: Paolo Bonzini , =?UTF-8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= Subject: [PATCH 1/3] KVM: X86: Implement PV sched yield in linux guest Date: Mon, 27 May 2019 18:34:13 +0800 Message-Id: <1558953255-9432-2-git-send-email-wanpengli@tencent.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1558953255-9432-1-git-send-email-wanpengli@tencent.com> References: <1558953255-9432-1-git-send-email-wanpengli@tencent.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org From: Wanpeng Li When sending a call-function IPI-many to vCPUs, yield if any of the IPI target vCPUs was preempted, we just select the first preempted target vCPU which we found since the state of target vCPUs can change underneath and to avoid race conditions. Cc: Paolo Bonzini Cc: Radim Krčmář Signed-off-by: Wanpeng Li --- Documentation/virtual/kvm/hypercalls.txt | 11 +++++++++++ arch/x86/include/uapi/asm/kvm_para.h | 1 + arch/x86/kernel/kvm.c | 21 +++++++++++++++++++++ include/uapi/linux/kvm_para.h | 1 + 4 files changed, 34 insertions(+) diff --git a/Documentation/virtual/kvm/hypercalls.txt b/Documentation/virtual/kvm/hypercalls.txt index da24c13..da21065 100644 --- a/Documentation/virtual/kvm/hypercalls.txt +++ b/Documentation/virtual/kvm/hypercalls.txt @@ -141,3 +141,14 @@ a0 corresponds to the APIC ID in the third argument (a2), bit 1 corresponds to the APIC ID a2+1, and so on. Returns the number of CPUs to which the IPIs were delivered successfully. + +7. KVM_HC_SCHED_YIELD +------------------------ +Architecture: x86 +Status: active +Purpose: Hypercall used to yield if the IPI target vCPU is preempted + +a0: destination APIC ID + +Usage example: When sending a call-function IPI-many to vCPUs, yield if +any of the IPI target vCPUs was preempted. diff --git a/arch/x86/include/uapi/asm/kvm_para.h b/arch/x86/include/uapi/asm/kvm_para.h index 19980ec..d0bf77c 100644 --- a/arch/x86/include/uapi/asm/kvm_para.h +++ b/arch/x86/include/uapi/asm/kvm_para.h @@ -29,6 +29,7 @@ #define KVM_FEATURE_PV_TLB_FLUSH 9 #define KVM_FEATURE_ASYNC_PF_VMEXIT 10 #define KVM_FEATURE_PV_SEND_IPI 11 +#define KVM_FEATURE_PV_SCHED_YIELD 12 #define KVM_HINTS_REALTIME 0 diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c index 3f0cc82..54400c2 100644 --- a/arch/x86/kernel/kvm.c +++ b/arch/x86/kernel/kvm.c @@ -540,6 +540,21 @@ static void kvm_setup_pv_ipi(void) pr_info("KVM setup pv IPIs\n"); } +static void kvm_smp_send_call_func_ipi(const struct cpumask *mask) +{ + int cpu; + + native_send_call_func_ipi(mask); + + /* Make sure other vCPUs get a chance to run if they need to. */ + for_each_cpu(cpu, mask) { + if (vcpu_is_preempted(cpu)) { + kvm_hypercall1(KVM_HC_SCHED_YIELD, per_cpu(x86_cpu_to_apicid, cpu)); + break; + } + } +} + static void __init kvm_smp_prepare_cpus(unsigned int max_cpus) { native_smp_prepare_cpus(max_cpus); @@ -651,6 +666,12 @@ static void __init kvm_guest_init(void) #ifdef CONFIG_SMP smp_ops.smp_prepare_cpus = kvm_smp_prepare_cpus; smp_ops.smp_prepare_boot_cpu = kvm_smp_prepare_boot_cpu; + if (kvm_para_has_feature(KVM_FEATURE_PV_SCHED_YIELD) && + !kvm_para_has_hint(KVM_HINTS_REALTIME) && + kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) { + smp_ops.send_call_func_ipi = kvm_smp_send_call_func_ipi; + pr_info("KVM setup pv sched yield\n"); + } if (cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "x86/kvm:online", kvm_cpu_online, kvm_cpu_down_prepare) < 0) pr_err("kvm_guest: Failed to install cpu hotplug callbacks\n"); diff --git a/include/uapi/linux/kvm_para.h b/include/uapi/linux/kvm_para.h index 6c0ce49..8b86609 100644 --- a/include/uapi/linux/kvm_para.h +++ b/include/uapi/linux/kvm_para.h @@ -28,6 +28,7 @@ #define KVM_HC_MIPS_CONSOLE_OUTPUT 8 #define KVM_HC_CLOCK_PAIRING 9 #define KVM_HC_SEND_IPI 10 +#define KVM_HC_SCHED_YIELD 11 /* * hypercalls use architecture specific -- 2.7.4