From patchwork Mon May 10 17:26:50 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Marcelo Tosatti X-Patchwork-Id: 12249177 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 0AEDAC433B4 for ; Mon, 10 May 2021 17:54:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D9080611F0 for ; Mon, 10 May 2021 17:54:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233266AbhEJRzn (ORCPT ); Mon, 10 May 2021 13:55:43 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:21051 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233258AbhEJRze (ORCPT ); Mon, 10 May 2021 13:55:34 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1620669269; 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=tTRqfX0l0K+r+0j2GyFDtK8NMSba2t7HpOpFLFds5Q8=; b=Ut4da1+ildEtDQVBSjO2riXLdXoyXZ0hUbKMf/9BAVSSbDaY6Bh/YGr27msOb4F0Wy7h+e lC59Dw0uNTmQSGwZyIQrae7Xpkei7yiD13dP+4EtFKKaur5H+wXWqtMXNEsw2vQilYBkfx dAsgECx0TrN4MeBw4f6o9kcZamX3FiA= 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-40-G1Eq-2NcOdqDEBDKqr3zHw-1; Mon, 10 May 2021 13:54:28 -0400 X-MC-Unique: G1Eq-2NcOdqDEBDKqr3zHw-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 2550A8015F7; Mon, 10 May 2021 17:54:27 +0000 (UTC) Received: from fuller.cnet (ovpn-112-8.gru2.redhat.com [10.97.112.8]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 4E9A35D6D1; Mon, 10 May 2021 17:54:20 +0000 (UTC) Received: by fuller.cnet (Postfix, from userid 1000) id 847114401883; Mon, 10 May 2021 14:54:15 -0300 (-03) Message-ID: <20210510172818.025080848@redhat.com> User-Agent: quilt/0.66 Date: Mon, 10 May 2021 14:26:50 -0300 From: Marcelo Tosatti To: kvm@vger.kernel.org Cc: Paolo Bonzini , Alex Williamson , Sean Christopherson , Peter Xu , Pei Zhang , Marcelo Tosatti Subject: [patch 4/4] KVM: VMX: update vcpu posted-interrupt descriptor when assigning device References: <20210510172646.930550753@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 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 kick vcpus out of the halt loop, so the notification vector is properly reprogrammed to the wakeup vector. 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 @@ -204,6 +204,32 @@ void pi_post_block(struct kvm_vcpu *vcpu } /* + * Bail out of the block loop if the VM has an assigned + * device, but the blocking vCPU didn't reconfigure the + * PI.NV to the wakeup vector, i.e. the assigned device + * came along after the initial check in vcpu_block(). + */ + +int vmx_vcpu_check_block(struct kvm_vcpu *vcpu) +{ + struct pi_desc *pi_desc = vcpu_to_pi_desc(vcpu); + + if (!irq_remapping_cap(IRQ_POSTING_CAP)) + return 0; + + if (!kvm_vcpu_apicv_active(vcpu)) + return 0; + + if (!kvm_arch_has_assigned_device(vcpu->kvm)) + return 0; + + if (pi_desc->nv == POSTED_INTR_WAKEUP_VECTOR) + return 0; + + return 1; +} + +/* * Handler for POSTED_INTERRUPT_WAKEUP_VECTOR. */ void pi_wakeup_handler(void) @@ -236,6 +262,25 @@ bool pi_has_pending_interrupt(struct kvm (pi_test_sn(pi_desc) && !pi_is_pir_empty(pi_desc)); } +void vmx_pi_start_assignment(struct kvm *kvm) +{ + struct kvm_vcpu *vcpu; + int i; + + if (!irq_remapping_cap(IRQ_POSTING_CAP)) + return; + + /* + * Wakeup will cause the vCPU to bail out of kvm_vcpu_block() and + * go back through vcpu_block(). + */ + kvm_for_each_vcpu(i, vcpu, kvm) { + if (!kvm_vcpu_apicv_active(vcpu)) + continue; + + kvm_vcpu_wake_up(vcpu); + } +} /* * 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 +95,7 @@ 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 vmx_vcpu_check_block(struct kvm_vcpu *vcpu); #endif /* __KVM_X86_VMX_POSTED_INTR_H */ Index: kvm/arch/x86/kvm/vmx/vmx.c =================================================================== --- kvm.orig/arch/x86/kvm/vmx/vmx.c +++ kvm/arch/x86/kvm/vmx/vmx.c @@ -7727,13 +7727,13 @@ static struct kvm_x86_ops vmx_x86_ops __ .pre_block = vmx_pre_block, .post_block = vmx_post_block, - .vcpu_check_block = NULL, + .vcpu_check_block = vmx_vcpu_check_block, .pmu_ops = &intel_pmu_ops, .nested_ops = &vmx_nested_ops, .update_pi_irte = pi_update_irte, - .start_assignment = NULL, + .start_assignment = vmx_pi_start_assignment, #ifdef CONFIG_X86_64 .set_hv_timer = vmx_set_hv_timer,