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=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,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 5F5C1C04EB9 for ; Mon, 3 Dec 2018 12:59:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 237A520834 for ; Mon, 3 Dec 2018 12:59:29 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 237A520834 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725897AbeLCNAX (ORCPT ); Mon, 3 Dec 2018 08:00:23 -0500 Received: from mx1.redhat.com ([209.132.183.28]:39898 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725830AbeLCNAX (ORCPT ); Mon, 3 Dec 2018 08:00:23 -0500 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id A653D307DAA2; Mon, 3 Dec 2018 12:59:26 +0000 (UTC) Received: from [10.36.118.125] (unknown [10.36.118.125]) by smtp.corp.redhat.com (Postfix) with ESMTP id 04A2B601B9; Mon, 3 Dec 2018 12:59:23 +0000 (UTC) Subject: Re: [PATCH v4 02/14] X86/nVMX: handle_vmptrld: Copy the VMCS12 directly from guest memory To: KarimAllah Ahmed , rkrcmar@redhat.com, pbonzini@redhat.com, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, jmattson@google.com References: <1543829467-18025-1-git-send-email-karahmed@amazon.de> <1543829467-18025-3-git-send-email-karahmed@amazon.de> From: David Hildenbrand Openpgp: preference=signencrypt Autocrypt: addr=david@redhat.com; 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Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.3.1 MIME-Version: 1.0 In-Reply-To: <1543829467-18025-3-git-send-email-karahmed@amazon.de> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.42]); Mon, 03 Dec 2018 12:59:26 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 03.12.18 10:30, KarimAllah Ahmed wrote: > Copy the VMCS12 directly from guest memory instead of the map->copy->unmap > sequence. This also avoids using kvm_vcpu_gpa_to_page() and kmap() which > assumes that there is a "struct page" for guest memory. > > Signed-off-by: KarimAllah Ahmed > --- > v3 -> v4: > - Return VMXERR_VMPTRLD_INCORRECT_VMCS_REVISION_ID on failure (jmattson@) > v1 -> v2: > - Massage commit message a bit. > --- > arch/x86/kvm/vmx.c | 24 ++++++++++++------------ > 1 file changed, 12 insertions(+), 12 deletions(-) > > diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c > index b84f230..75817cb 100644 > --- a/arch/x86/kvm/vmx.c > +++ b/arch/x86/kvm/vmx.c > @@ -9301,20 +9301,22 @@ static int handle_vmptrld(struct kvm_vcpu *vcpu) > return 1; > > if (vmx->nested.current_vmptr != vmptr) { > - struct vmcs12 *new_vmcs12; > - struct page *page; > - page = kvm_vcpu_gpa_to_page(vcpu, vmptr); > - if (is_error_page(page)) > - return nested_vmx_failInvalid(vcpu); > + struct vmcs12 *new_vmcs12 = (struct vmcs12 *)__get_free_page(GFP_KERNEL); > + > + if (!new_vmcs12 || > + kvm_read_guest(vcpu->kvm, vmptr, new_vmcs12, > + sizeof(*new_vmcs12))) { > + free_page((unsigned long)new_vmcs12); > + return nested_vmx_failValid(vcpu, > + VMXERR_VMPTRLD_INCORRECT_VMCS_REVISION_ID); > + } If we fail to read, VMXERR_VMPTRLD_INCORRECT_VMCS_REVISION_ID seems t be the right thing to do (I remember that reading from non-existent memory returns all 1's). I somewhat dislike that we are converting -ENOMEM to VMXERR_VMPTRLD_INCORRECT_VMCS_REVISION_ID. Isn't there a way we can report -ENOMEM to user space? (or do we really want to avoid crashing the guest here? if so, comment + print a warning or something like that?) > > - new_vmcs12 = kmap(page); > if (new_vmcs12->hdr.revision_id != VMCS12_REVISION || > (new_vmcs12->hdr.shadow_vmcs && > !nested_cpu_has_vmx_shadow_vmcs(vcpu))) { > - kunmap(page); > - kvm_release_page_clean(page); > + free_page((unsigned long)new_vmcs12); > return nested_vmx_failValid(vcpu, > - VMXERR_VMPTRLD_INCORRECT_VMCS_REVISION_ID); > + VMXERR_VMPTRLD_INCORRECT_VMCS_REVISION_ID); > } > > nested_release_vmcs12(vcpu); > @@ -9324,9 +9326,7 @@ static int handle_vmptrld(struct kvm_vcpu *vcpu) > * cached. > */ > memcpy(vmx->nested.cached_vmcs12, new_vmcs12, VMCS12_SIZE); > - kunmap(page); > - kvm_release_page_clean(page); > - > + free_page((unsigned long)new_vmcs12); > set_current_vmptr(vmx, vmptr); > } > > -- Thanks, David / dhildenb