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 D3658C04FF3 for ; Mon, 24 May 2021 12:13:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B388C610C8 for ; Mon, 24 May 2021 12:13:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232678AbhEXMOu (ORCPT ); Mon, 24 May 2021 08:14:50 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:55518 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232494AbhEXMOt (ORCPT ); Mon, 24 May 2021 08:14:49 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1621858401; 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=VHS7kDDRvF5zOyGIv8drTO+Pb6C7Uho8V01CDj2scXk=; b=HXGqBKQoOKPIcquXx/RwHjf4xPfG5PmUU3nz2CV7Xv5vffZnOSHHMPDD4XchWITcQVDCNe sYPdxFbxHeHPP8By6VRvdfS0kkotFipLJrD/yodbxpElubWaDkhC2dMqbX55OMpHX0kTZp EfpfkqOCmqxsBHnSaCEmakKJjCYkBjc= 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-427-xqcLxzkAOvGzwvBOX-FM5g-1; Mon, 24 May 2021 08:13:19 -0400 X-MC-Unique: xqcLxzkAOvGzwvBOX-FM5g-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 5D7D58042C9; Mon, 24 May 2021 12:13:18 +0000 (UTC) Received: from starship (unknown [10.40.192.15]) by smtp.corp.redhat.com (Postfix) with ESMTP id 2DDCB7086A; Mon, 24 May 2021 12:13:15 +0000 (UTC) Message-ID: <779a182e7ed08484658463a69cf3934dcc87464d.camel@redhat.com> Subject: Re: [PATCH v2 2/7] KVM: nVMX: Release enlightened VMCS on VMCLEAR 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: Mon, 24 May 2021 15:13:14 +0300 In-Reply-To: <20210517135054.1914802-3-vkuznets@redhat.com> References: <20210517135054.1914802-1-vkuznets@redhat.com> <20210517135054.1914802-3-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 10.5.11.13 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Mon, 2021-05-17 at 15:50 +0200, Vitaly Kuznetsov wrote: > Unlike VMREAD/VMWRITE/VMPTRLD, VMCLEAR is a valid instruction when > enlightened VMCS is in use. TLFS has the following brief description: > "The L1 hypervisor can execute a VMCLEAR instruction to transition an > enlightened VMCS from the active to the non-active state". Normally, > this change can be ignored as unmapping active eVMCS can be postponed > until the next VMLAUNCH instruction but in case nested state is migrated > with KVM_GET_NESTED_STATE/KVM_SET_NESTED_STATE, keeping eVMCS mapped > may result in its synchronization with VMCS12 and this is incorrect: > L1 hypervisor is free to reuse inactive eVMCS memory for something else. > > Inactive eVMCS after VMCLEAR can just be unmapped. > > Signed-off-by: Vitaly Kuznetsov > --- > arch/x86/kvm/vmx/nested.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c > index 3080e00c8f90..ea2869d8b823 100644 > --- a/arch/x86/kvm/vmx/nested.c > +++ b/arch/x86/kvm/vmx/nested.c > @@ -5008,6 +5008,8 @@ static int handle_vmclear(struct kvm_vcpu *vcpu) > vmptr + offsetof(struct vmcs12, > launch_state), > &zero, sizeof(zero)); > + } else if (vmx->nested.hv_evmcs && vmptr == vmx->nested.hv_evmcs_vmptr) { > + nested_release_evmcs(vcpu); > } Releasing the eVMCS is a good thing not only for migration but for instance for nested_vmx_fail which could write to current eVMCS even outside of nested mode (there is a bug there but you fixed it in the patch 4). Reviewed-by: Maxim Levitsky Best regards, Maxim Levitsky > > return nested_vmx_succeed(vcpu);