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 6B4B6C4743C for ; Wed, 23 Jun 2021 11:31:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 57268610F7 for ; Wed, 23 Jun 2021 11:31:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231129AbhFWLdY (ORCPT ); Wed, 23 Jun 2021 07:33:24 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:37267 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231168AbhFWLdR (ORCPT ); Wed, 23 Jun 2021 07:33:17 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1624447859; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=a+VbfBqva2ZepZH50mdoNvto+ALQgMugS30ADzU4me0=; b=WKTZwDCzm9pYetcsM1vYlp3D2l5fVNDZzz7eaIWnViZDTI3kqPZKwkmi+FIOzEQLtqB/9A 5HMIfTD/CepDRbwUDHif9pUqvVMJchE8c9/Fsu5UO6+g/x3v9ccsiBqh2+zFdtcr+7ThV2 gdyNXuYByLygMZGv2N3owZOcm28f2Bw= 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-589-VefzVtE3P5OELzTcYFhQVA-1; Wed, 23 Jun 2021 07:30:58 -0400 X-MC-Unique: VefzVtE3P5OELzTcYFhQVA-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 37C51362FE; Wed, 23 Jun 2021 11:30:56 +0000 (UTC) Received: from localhost.localdomain (unknown [10.40.192.10]) by smtp.corp.redhat.com (Postfix) with ESMTP id 9C0935D740; Wed, 23 Jun 2021 11:30:49 +0000 (UTC) From: Maxim Levitsky To: kvm@vger.kernel.org Cc: Thomas Gleixner , Sean Christopherson , Wanpeng Li , Vitaly Kuznetsov , Joerg Roedel , Borislav Petkov , "H. Peter Anvin" , Ingo Molnar , Paolo Bonzini , linux-kernel@vger.kernel.org (open list:X86 ARCHITECTURE (32-BIT AND 64-BIT)), x86@kernel.org (maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)), Jim Mattson , Maxim Levitsky Subject: [PATCH 10/10] KVM: x86: hyper-v: Deactivate APICv only when AutoEOI feature is in use Date: Wed, 23 Jun 2021 14:30:02 +0300 Message-Id: <20210623113002.111448-11-mlevitsk@redhat.com> In-Reply-To: <20210623113002.111448-1-mlevitsk@redhat.com> References: <20210623113002.111448-1-mlevitsk@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org From: Vitaly Kuznetsov APICV_INHIBIT_REASON_HYPERV is currently unconditionally forced upon SynIC activation as SynIC's AutoEOI is incompatible with APICv/AVIC. It is, however, possible to track whether the feature was actually used by the guest and only inhibit APICv/AVIC when needed. TLFS suggests a dedicated 'HV_DEPRECATING_AEOI_RECOMMENDED' flag to let Windows know that AutoEOI feature should be avoided. While it's up to KVM userspace to set the flag, KVM can help a bit by exposing global APICv/AVIC enablement: in case APICv/AVIC usage is impossible, AutoEOI is still preferred. Maxim: - Drop SRCU lock around the call to kvm_request_apicv_update to avoid deadlock. - Always set HV_DEPRECATING_AEOI_RECOMMENDED in kvm_get_hv_cpuid, since this feature can be used regardless of APICv. Signed-off-by: Vitaly Kuznetsov Signed-off-by: Maxim Levitsky --- arch/x86/include/asm/kvm_host.h | 3 +++ arch/x86/kvm/hyperv.c | 34 +++++++++++++++++++++++++++------ 2 files changed, 31 insertions(+), 6 deletions(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 9ed5c55be352..9eb78ec6a290 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -956,6 +956,9 @@ struct kvm_hv { /* How many vCPUs have VP index != vCPU index */ atomic_t num_mismatched_vp_indexes; + /* How many SynICs use 'AutoEOI' feature */ + atomic_t synic_auto_eoi_used; + struct hv_partition_assist_pg *hv_pa_pg; struct kvm_hv_syndbg hv_syndbg; }; diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c index b07592ca92f0..6bf47a583d0e 100644 --- a/arch/x86/kvm/hyperv.c +++ b/arch/x86/kvm/hyperv.c @@ -85,9 +85,22 @@ static bool synic_has_vector_auto_eoi(struct kvm_vcpu_hv_synic *synic, return false; } + +static void synic_toggle_avic(struct kvm_vcpu *vcpu, bool activate) +{ + srcu_read_unlock(&vcpu->kvm->srcu, vcpu->srcu_idx); + kvm_request_apicv_update(vcpu->kvm, activate, + APICV_INHIBIT_REASON_HYPERV); + vcpu->srcu_idx = srcu_read_lock(&vcpu->kvm->srcu); +} + static void synic_update_vector(struct kvm_vcpu_hv_synic *synic, int vector) { + struct kvm_vcpu *vcpu = hv_synic_to_vcpu(synic); + struct kvm_hv *hv = to_kvm_hv(vcpu->kvm); + int auto_eoi_old, auto_eoi_new; + if (vector < HV_SYNIC_FIRST_VALID_VECTOR) return; @@ -96,10 +109,23 @@ static void synic_update_vector(struct kvm_vcpu_hv_synic *synic, else __clear_bit(vector, synic->vec_bitmap); + auto_eoi_old = bitmap_weight(synic->auto_eoi_bitmap, 256); + if (synic_has_vector_auto_eoi(synic, vector)) __set_bit(vector, synic->auto_eoi_bitmap); else __clear_bit(vector, synic->auto_eoi_bitmap); + + auto_eoi_new = bitmap_weight(synic->auto_eoi_bitmap, 256); + + /* Hyper-V SynIC auto EOI SINTs are not compatible with APICV */ + if (!auto_eoi_old && auto_eoi_new) { + if (atomic_inc_return(&hv->synic_auto_eoi_used) == 1) + synic_toggle_avic(vcpu, false); + } else if (!auto_eoi_new && auto_eoi_old) { + if (atomic_dec_return(&hv->synic_auto_eoi_used) == 0) + synic_toggle_avic(vcpu, true); + } } static int synic_set_sint(struct kvm_vcpu_hv_synic *synic, int sint, @@ -933,12 +959,6 @@ int kvm_hv_activate_synic(struct kvm_vcpu *vcpu, bool dont_zero_synic_pages) synic = to_hv_synic(vcpu); - /* - * Hyper-V SynIC auto EOI SINT's are - * not compatible with APICV, so request - * to deactivate APICV permanently. - */ - kvm_request_apicv_update(vcpu->kvm, false, APICV_INHIBIT_REASON_HYPERV); synic->active = true; synic->dont_zero_synic_pages = dont_zero_synic_pages; synic->control = HV_SYNIC_CONTROL_ENABLE; @@ -2466,6 +2486,8 @@ int kvm_get_hv_cpuid(struct kvm_vcpu *vcpu, struct kvm_cpuid2 *cpuid, ent->eax |= HV_X64_ENLIGHTENED_VMCS_RECOMMENDED; if (!cpu_smt_possible()) ent->eax |= HV_X64_NO_NONARCH_CORESHARING; + + ent->eax |= HV_DEPRECATING_AEOI_RECOMMENDED; /* * Default number of spinlock retry attempts, matches * HyperV 2016. -- 2.26.3