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=unavailable 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 B0312C433EF for ; Sun, 12 Sep 2021 15:59:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 961FB61076 for ; Sun, 12 Sep 2021 15:59:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235906AbhILQAr (ORCPT ); Sun, 12 Sep 2021 12:00:47 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:51193 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235859AbhILQAn (ORCPT ); Sun, 12 Sep 2021 12:00:43 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1631462368; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=EIz1j32cEU4UBvdCYECfO6tqdzMXyCcE0af4yJCjxKU=; b=NaJBkAPUc/7jyb+BfMkJCJuKTLZgdTvrLEUloHwSNjPUGAM6QPDGrB9LrI5/0Yy8GYPBP1 44UXgJcO7Ot5xuwCtzMQd+glWuw9QnPhyb37AlwdHifrttXE5xIuzvKHcsF+OExTw4hYxM KEsPuDcvhyxaT2ZWGRX8et1E9RzM+Aw= 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-372-U3ByrgX4PzyX9lHqkewKHQ-1; Sun, 12 Sep 2021 11:59:25 -0400 X-MC-Unique: U3ByrgX4PzyX9lHqkewKHQ-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 953AC1084683; Sun, 12 Sep 2021 15:59:24 +0000 (UTC) Received: from starship (unknown [10.35.206.50]) by smtp.corp.redhat.com (Postfix) with ESMTP id 0C3985D9D3; Sun, 12 Sep 2021 15:59:18 +0000 (UTC) Message-ID: <37efb41fda41317bf04c0cb805792af261894a1a.camel@redhat.com> Subject: Re: [PATCH 3/4] KVM: nVMX: Track whether changes in L0 require MSR bitmap for L2 to be rebuilt From: Maxim Levitsky To: Vitaly Kuznetsov , kvm@vger.kernel.org, Paolo Bonzini Cc: Sean Christopherson , Wanpeng Li , Jim Mattson , linux-kernel@vger.kernel.org Date: Sun, 12 Sep 2021 18:59:17 +0300 In-Reply-To: <20210910160633.451250-4-vkuznets@redhat.com> References: <20210910160633.451250-1-vkuznets@redhat.com> <20210910160633.451250-4-vkuznets@redhat.com> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.36.5 (3.36.5-2.fc32) MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 2021-09-10 at 18:06 +0200, Vitaly Kuznetsov wrote: > Introduce a flag to keep track of whether MSR bitmap for L2 needs to be > rebuilt due to changes in MSR bitmap for L1 or switching to a different > L2. This information will be used for Enlightened MSR Bitmap feature for > Hyper-V guests. > > Note, setting msr_bitmap_changed to 'true' from set_current_vmptr() is > not really needed for Enlightened MSR Bitmap as the feature can only > be used in conjunction with Enlightened VMCS but let's keep tracking > information complete, it's cheap and in the future similar PV feature can > easily be implemented for KVM on KVM too. > > No functional change intended. > > Signed-off-by: Vitaly Kuznetsov > --- > arch/x86/kvm/vmx/nested.c | 9 ++++++++- > arch/x86/kvm/vmx/vmx.c | 2 ++ > arch/x86/kvm/vmx/vmx.h | 6 ++++++ > 3 files changed, 16 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c > index ccb03d69546c..42cd95611892 100644 > --- a/arch/x86/kvm/vmx/nested.c > +++ b/arch/x86/kvm/vmx/nested.c > @@ -2053,10 +2053,13 @@ static enum nested_evmptrld_status nested_vmx_handle_enlightened_vmptrld( > * Clean fields data can't be used on VMLAUNCH and when we switch > * between different L2 guests as KVM keeps a single VMCS12 per L1. > */ > - if (from_launch || evmcs_gpa_changed) > + if (from_launch || evmcs_gpa_changed) { > vmx->nested.hv_evmcs->hv_clean_fields &= > ~HV_VMX_ENLIGHTENED_CLEAN_FIELD_ALL; > > + vmx->nested.msr_bitmap_changed = true; > + } > + > return EVMPTRLD_SUCCEEDED; > } > > @@ -3240,6 +3243,8 @@ static bool nested_get_vmcs12_pages(struct kvm_vcpu *vcpu) > else > exec_controls_clearbit(vmx, CPU_BASED_USE_MSR_BITMAPS); > > + vmx->nested.msr_bitmap_changed = false; Very minor nitpick: Maybe I would put this into nested_vmx_prepare_msr_bitmap, a bit closer to the action, but this is fine like this as well. > + > return true; > } > > @@ -5273,6 +5278,7 @@ static void set_current_vmptr(struct vcpu_vmx *vmx, gpa_t vmptr) > vmx->nested.need_vmcs12_to_shadow_sync = true; > } > vmx->nested.dirty_vmcs12 = true; > + vmx->nested.msr_bitmap_changed = true; > } > > /* Emulate the VMPTRLD instruction */ > @@ -6393,6 +6399,7 @@ static int vmx_set_nested_state(struct kvm_vcpu *vcpu, > goto error_guest_mode; > > vmx->nested.dirty_vmcs12 = true; > + vmx->nested.msr_bitmap_changed = true; Is this needed? Setting the nested state should eventually trigger call to nested_vmx_handle_enlightened_vmptrld. > ret = nested_vmx_enter_non_root_mode(vcpu, false); > if (ret) > goto error_guest_mode; > diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c > index ad33032e8588..2dbfb5d838db 100644 > --- a/arch/x86/kvm/vmx/vmx.c > +++ b/arch/x86/kvm/vmx/vmx.c > @@ -3734,6 +3734,8 @@ static void vmx_msr_bitmap_l01_changed(struct vcpu_vmx *vmx) > */ > if (static_branch_unlikely(&enable_evmcs)) > evmcs_touch_msr_bitmap(); > + > + vmx->nested.msr_bitmap_changed = true; > } > > void vmx_disable_intercept_for_msr(struct kvm_vcpu *vcpu, u32 msr, int type) > diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h > index 4858c5fd95f2..b6596fc2943a 100644 > --- a/arch/x86/kvm/vmx/vmx.h > +++ b/arch/x86/kvm/vmx/vmx.h > @@ -148,6 +148,12 @@ struct nested_vmx { > bool need_vmcs12_to_shadow_sync; > bool dirty_vmcs12; > > + /* > + * Indicates whether MSR bitmap for L2 needs to be rebuilt due to > + * changes in MSR bitmap for L1 or switching to a different L2. > + */ > + bool msr_bitmap_changed; > + > /* > * Indicates lazily loaded guest state has not yet been decached from > * vmcs02. Best regards, Maxim Levitsky