From patchwork Thu May 13 11:37:10 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vitaly Kuznetsov X-Patchwork-Id: 12255631 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=-16.5 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 AA027C433ED for ; Thu, 13 May 2021 11:37:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8A5C861443 for ; Thu, 13 May 2021 11:37:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233464AbhEMLix (ORCPT ); Thu, 13 May 2021 07:38:53 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:20848 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233462AbhEMLif (ORCPT ); Thu, 13 May 2021 07:38:35 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1620905845; 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=POOI9TCezc4J5RJIxcGbqShjc8zde1SEv1yU+Nd1U/A=; b=IE8FZww4CW7XMKunzZuyaRrCFDIprnZW2azb1HYqypQKAGuSSAsMfwOcRa6LZ0uGyu8F6w eoXfQ7htgseVGng2o88Lpf6PdlCUQNn40u6bMr00sK9MjQYMWnksQkOZeGI7vTBOSNOHsZ yuyW9IGkC6FFFuRMm8wf36Ue7WwotWU= 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-395-FwTgx3IBPfy3bDywU2sc7Q-1; Thu, 13 May 2021 07:37:21 -0400 X-MC-Unique: FwTgx3IBPfy3bDywU2sc7Q-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 78E518015DB; Thu, 13 May 2021 11:37:20 +0000 (UTC) Received: from vitty.brq.redhat.com (unknown [10.40.193.2]) by smtp.corp.redhat.com (Postfix) with ESMTP id 4183010074E5; Thu, 13 May 2021 11:37:18 +0000 (UTC) From: Vitaly Kuznetsov To: kvm@vger.kernel.org, Paolo Bonzini Cc: Sean Christopherson , Wanpeng Li , Jim Mattson , Kechen Lu , Maxim Levitsky , linux-kernel@vger.kernel.org Subject: [PATCH 2/2] KVM: x86: hyper-v: Deactivate APICv only when AutoEOI feature is in use Date: Thu, 13 May 2021 13:37:10 +0200 Message-Id: <20210513113710.1740398-3-vkuznets@redhat.com> In-Reply-To: <20210513113710.1740398-1-vkuznets@redhat.com> References: <20210513113710.1740398-1-vkuznets@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 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. Signed-off-by: Vitaly Kuznetsov --- arch/x86/include/asm/kvm_host.h | 3 +++ arch/x86/kvm/hyperv.c | 27 +++++++++++++++++++++------ 2 files changed, 24 insertions(+), 6 deletions(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index ffafdb7b24cb..98391c9c18df 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -936,6 +936,9 @@ 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 f98370a39936..e1ecc2143794 100644 --- a/arch/x86/kvm/hyperv.c +++ b/arch/x86/kvm/hyperv.c @@ -87,6 +87,10 @@ static bool synic_has_vector_auto_eoi(struct kvm_vcpu_hv_synic *synic, 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; @@ -95,10 +99,25 @@ 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) + kvm_request_apicv_update(vcpu->kvm, false, + APICV_INHIBIT_REASON_HYPERV); + } else if (!auto_eoi_new && auto_eoi_old) { + if (atomic_dec_return(&hv->synic_auto_eoi_used) == 0) + kvm_request_apicv_update(vcpu->kvm, true, + APICV_INHIBIT_REASON_HYPERV); + } } static int synic_set_sint(struct kvm_vcpu_hv_synic *synic, int sint, @@ -931,12 +950,6 @@ 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; @@ -2198,6 +2211,8 @@ 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; + if (kvm_x86_ops.apicv_supported()) + ent->eax |= HV_DEPRECATING_AEOI_RECOMMENDED; /* * Default number of spinlock retry attempts, matches * HyperV 2016.