From patchwork Thu May 6 18:57:34 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Marcelo Tosatti X-Patchwork-Id: 12243395 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=-16.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 8DA41C43460 for ; Thu, 6 May 2021 19:07:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 694D6613E4 for ; Thu, 6 May 2021 19:07:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234751AbhEFTIi (ORCPT ); Thu, 6 May 2021 15:08:38 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:20396 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234740AbhEFTIh (ORCPT ); Thu, 6 May 2021 15:08:37 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1620328058; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: references:references; bh=wLvxEYJuVXW97IlxUCoSSxvp9ugeIbjO4WWeDL9ilCI=; b=hBlS8EC4ugynh/Vk1n9XIvcT3FvHIm5vcFZ69V4tUpdaByEVdqdBpPFZsbVQOh5sZGb3Cu F0joawPPJwjhAqfbrz1KmcUAKocxlqiMsXx2Go/m7TuM8MqcoveAr0/FTNQrf8aQwXKYE4 M4zIGmFcICkzg+eN6ChChAGRRCGCr/s= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-271-caUZCGBNPCqw_v0SUe_ZAw-1; Thu, 06 May 2021 15:07:34 -0400 X-MC-Unique: caUZCGBNPCqw_v0SUe_ZAw-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 8FEAA107ACCD; Thu, 6 May 2021 19:07:33 +0000 (UTC) Received: from fuller.cnet (ovpn-112-4.gru2.redhat.com [10.97.112.4]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 92C2D10027A5; Thu, 6 May 2021 19:07:23 +0000 (UTC) Received: by fuller.cnet (Postfix, from userid 1000) id EC62240B1EB1; Thu, 6 May 2021 16:07:03 -0300 (-03) Message-ID: <20210506190419.481236922@redhat.com> User-Agent: quilt/0.66 Date: Thu, 06 May 2021 15:57:34 -0300 From: Marcelo Tosatti To: kvm@vger.kernel.org Cc: Paolo Bonzini , Alex Williamson , Sean Christopherson , Pei Zhang , Marcelo Tosatti Subject: [patch 2/2] KVM: VMX: update vcpu posted-interrupt descriptor when assigning device References: <20210506185732.609010123@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org For VMX, when a vcpu enters HLT emulation, pi_post_block will: 1) Add vcpu to per-cpu list of blocked vcpus. 2) Program the posted-interrupt descriptor "notification vector" to POSTED_INTR_WAKEUP_VECTOR With interrupt remapping, an interrupt will set the PIR bit for the vector programmed for the device on the CPU, test-and-set the ON bit on the posted interrupt descriptor, and if the ON bit is clear generate an interrupt for the notification vector. This way, the target CPU wakes upon a device interrupt and wakes up the target vcpu. Problem is that pi_post_block only programs the notification vector if kvm_arch_has_assigned_device() is true. Its possible for the following to happen: 1) vcpu V HLTs on pcpu P, kvm_arch_has_assigned_device is false, notification vector is not programmed 2) device is assigned to VM 3) device interrupts vcpu V, sets ON bit (notification vector not programmed, so pcpu P remains in idle) 4) vcpu 0 IPIs vcpu V (in guest), but since pi descriptor ON bit is set, kvm_vcpu_kick is skipped 5) vcpu 0 busy spins on vcpu V's response for several seconds, until RCU watchdog NMIs all vCPUs. To fix this, use the start_assignment kvm_x86_ops callback to program the notification vector when assigned device count changes from 0 to 1. Reported-by: Pei Zhang Signed-off-by: Marcelo Tosatti Index: kvm/arch/x86/kvm/vmx/posted_intr.c =================================================================== --- kvm.orig/arch/x86/kvm/vmx/posted_intr.c +++ kvm/arch/x86/kvm/vmx/posted_intr.c @@ -114,7 +114,7 @@ static void __pi_post_block(struct kvm_v } while (cmpxchg64(&pi_desc->control, old.control, new.control) != old.control); - if (!WARN_ON_ONCE(vcpu->pre_pcpu == -1)) { + if (vcpu->pre_pcpu != -1) { spin_lock(&per_cpu(blocked_vcpu_on_cpu_lock, vcpu->pre_pcpu)); list_del(&vcpu->blocked_vcpu_list); spin_unlock(&per_cpu(blocked_vcpu_on_cpu_lock, vcpu->pre_pcpu)); @@ -135,20 +135,13 @@ static void __pi_post_block(struct kvm_v * this case, return 1, otherwise, return 0. * */ -int pi_pre_block(struct kvm_vcpu *vcpu) +static int __pi_pre_block(struct kvm_vcpu *vcpu) { unsigned int dest; struct pi_desc old, new; struct pi_desc *pi_desc = vcpu_to_pi_desc(vcpu); - if (!kvm_arch_has_assigned_device(vcpu->kvm) || - !irq_remapping_cap(IRQ_POSTING_CAP) || - !kvm_vcpu_apicv_active(vcpu)) - return 0; - - WARN_ON(irqs_disabled()); - local_irq_disable(); - if (!WARN_ON_ONCE(vcpu->pre_pcpu != -1)) { + if (vcpu->pre_pcpu == -1) { vcpu->pre_pcpu = vcpu->cpu; spin_lock(&per_cpu(blocked_vcpu_on_cpu_lock, vcpu->pre_pcpu)); list_add_tail(&vcpu->blocked_vcpu_list, @@ -188,12 +181,33 @@ int pi_pre_block(struct kvm_vcpu *vcpu) if (pi_test_on(pi_desc) == 1) __pi_post_block(vcpu); + return (vcpu->pre_pcpu == -1); +} + +int pi_pre_block(struct kvm_vcpu *vcpu) +{ + struct vcpu_vmx *vmx = to_vmx(vcpu); + + vmx->in_blocked_section = true; + + if (!kvm_arch_has_assigned_device(vcpu->kvm) || + !irq_remapping_cap(IRQ_POSTING_CAP) || + !kvm_vcpu_apicv_active(vcpu)) + return 0; + + WARN_ON(irqs_disabled()); + local_irq_disable(); + __pi_pre_block(vcpu); local_irq_enable(); + return (vcpu->pre_pcpu == -1); } void pi_post_block(struct kvm_vcpu *vcpu) { + struct vcpu_vmx *vmx = to_vmx(vcpu); + + vmx->in_blocked_section = false; if (vcpu->pre_pcpu == -1) return; @@ -236,6 +250,52 @@ bool pi_has_pending_interrupt(struct kvm (pi_test_sn(pi_desc) && !pi_is_pir_empty(pi_desc)); } +static void pi_update_wakeup_vector(void *data) +{ + struct vcpu_vmx *vmx; + struct kvm_vcpu *vcpu = data; + + vmx = to_vmx(vcpu); + + /* race with pi_post_block ? */ + if (vcpu->pre_pcpu != -1) + return; + + if (!vmx->in_blocked_section) + return; + + __pi_pre_block(vcpu); +} + +void vmx_pi_start_assignment(struct kvm *kvm, int device_count) +{ + struct kvm_vcpu *vcpu; + int i; + + if (!irq_remapping_cap(IRQ_POSTING_CAP)) + return; + + /* only care about first device assignment */ + if (device_count != 1) + return; + + /* Update wakeup vector and add vcpu to blocked_vcpu_list */ + kvm_for_each_vcpu(i, vcpu, kvm) { + struct vcpu_vmx *vmx = to_vmx(vcpu); + int pcpu; + + if (!kvm_vcpu_apicv_active(vcpu)) + continue; + + preempt_disable(); + pcpu = vcpu->cpu; + if (vmx->in_blocked_section && vcpu->pre_pcpu == -1 && + pcpu != -1 && pcpu != smp_processor_id()) + smp_call_function_single(pcpu, pi_update_wakeup_vector, + vcpu, 1); + preempt_enable(); + } +} /* * pi_update_irte - set IRTE for Posted-Interrupts Index: kvm/arch/x86/kvm/vmx/posted_intr.h =================================================================== --- kvm.orig/arch/x86/kvm/vmx/posted_intr.h +++ kvm/arch/x86/kvm/vmx/posted_intr.h @@ -95,5 +95,6 @@ void __init pi_init_cpu(int cpu); bool pi_has_pending_interrupt(struct kvm_vcpu *vcpu); int pi_update_irte(struct kvm *kvm, unsigned int host_irq, uint32_t guest_irq, bool set); +void vmx_pi_start_assignment(struct kvm *kvm, int device_count); #endif /* __KVM_X86_VMX_POSTED_INTR_H */ Index: kvm/arch/x86/kvm/vmx/vmx.h =================================================================== --- kvm.orig/arch/x86/kvm/vmx/vmx.h +++ kvm/arch/x86/kvm/vmx/vmx.h @@ -336,6 +336,9 @@ struct vcpu_vmx { DECLARE_BITMAP(read, MAX_POSSIBLE_PASSTHROUGH_MSRS); DECLARE_BITMAP(write, MAX_POSSIBLE_PASSTHROUGH_MSRS); } shadow_msr_intercept; + + /* true if vcpu is between pre_block and post_block */ + bool in_blocked_section; }; enum ept_pointers_status {