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=-16.1 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 1D1DEC2B9F8 for ; Tue, 25 May 2021 13:54:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E924A61423 for ; Tue, 25 May 2021 13:54:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233417AbhEYNz5 (ORCPT ); Tue, 25 May 2021 09:55:57 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:45799 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233385AbhEYNzq (ORCPT ); Tue, 25 May 2021 09:55:46 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1621950856; 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=NPGYHoSnoFBe2Pyrr6tNPxDx3Mmjq4+YFrgUxsImBrY=; b=W1yOw9Es6U6bZhHrbK/MTb4lPyNysB9j/q20X37ji7MEHMtjACpZvctjvg91FVWGftu5WT ZZt2pmpundAr+L69mWQ6rvAe3I1HLX8qmoyNUJ+IgNgYm3TjWrcSlfTdFlzP4x8kuBdZJR cReVCbMQkU7cP4I8uQGOHYp6qN4PY3E= 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-551-L5hCDacVMDW_Knrk1BCamQ-1; Tue, 25 May 2021 09:54:15 -0400 X-MC-Unique: L5hCDacVMDW_Knrk1BCamQ-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 56464501E3; Tue, 25 May 2021 13:54:14 +0000 (UTC) Received: from fuller.cnet (ovpn-112-2.gru2.redhat.com [10.97.112.2]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 2B6B761094; Tue, 25 May 2021 13:54:07 +0000 (UTC) Received: by fuller.cnet (Postfix, from userid 1000) id B50D54179BB2; Tue, 25 May 2021 10:44:35 -0300 (-03) Message-ID: <20210525134321.345140341@redhat.com> User-Agent: quilt/0.66 Date: Tue, 25 May 2021 10:41:18 -0300 From: Marcelo Tosatti To: kvm@vger.kernel.org Cc: Paolo Bonzini , Alex Williamson , Sean Christopherson , Peter Xu , Pei Zhang , Marcelo Tosatti Subject: [patch 3/3] KVM: VMX: update vcpu posted-interrupt descriptor when assigning device References: <20210525134115.135966361@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 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 @@ -236,6 +236,13 @@ 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) +{ + if (!irq_remapping_cap(IRQ_POSTING_CAP)) + return; + + kvm_make_all_cpus_request(kvm, KVM_REQ_UNBLOCK); +} /* * 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); #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 @@ -7732,6 +7732,7 @@ static struct kvm_x86_ops vmx_x86_ops __ .nested_ops = &vmx_nested_ops, .update_pi_irte = pi_update_irte, + .start_assignment = vmx_pi_start_assignment, #ifdef CONFIG_X86_64 .set_hv_timer = vmx_set_hv_timer,