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=-0.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no 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 AE8CEC433E0 for ; Wed, 27 May 2020 15:17:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8F1A520C09 for ; Wed, 27 May 2020 15:17:52 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="KeOjlopP" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389668AbgE0PRw (ORCPT ); Wed, 27 May 2020 11:17:52 -0400 Received: from us-smtp-1.mimecast.com ([207.211.31.81]:34671 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S2389661AbgE0PRv (ORCPT ); Wed, 27 May 2020 11:17:51 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1590592670; 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=0qDCbXpJzNPAoB5fw7601W5Vqzwk6fSUzQmDBo8OEdQ=; b=KeOjlopPRjdvWbe8jLS8DDF2FvH+JfNeF3PiWgCpeQTRNfCnKiR3Q6EtlIfRiosjJx7/gd cpnbpkySSTkn/GgvIclnlySk+xa4lJZOug83T4qercAaoYyIZHM1GmYRwyiCIg2rFEq3Rq oQwBxCiwJQJzZNWvO4w3HPXn/msJY1E= 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-331-08sS3-wQMVGGNRHyWkuK6A-1; Wed, 27 May 2020 11:17:46 -0400 X-MC-Unique: 08sS3-wQMVGGNRHyWkuK6A-1 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 mimecast-mx01.redhat.com (Postfix) with ESMTPS id B794A800688; Wed, 27 May 2020 15:17:44 +0000 (UTC) Received: from starship (unknown [10.35.206.172]) by smtp.corp.redhat.com (Postfix) with ESMTP id 322E279C55; Wed, 27 May 2020 15:17:40 +0000 (UTC) Message-ID: <674dc359b794d0380f90dbb9c7d026b605d40c12.camel@redhat.com> Subject: Re: [PATCH 0/2] Fix issue with not starting nesting guests on my system From: Maxim Levitsky To: Sean Christopherson Cc: kvm@vger.kernel.org, Paolo Bonzini , "H. Peter Anvin" , Tao Xu , Jim Mattson , linux-kernel@vger.kernel.org, Joerg Roedel , "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" , Wanpeng Li , Ingo Molnar , Thomas Gleixner , Borislav Petkov , Vitaly Kuznetsov , Jingqi Liu Date: Wed, 27 May 2020 18:17:40 +0300 In-Reply-To: <20200527011344.GB31696@linux.intel.com> References: <20200523161455.3940-1-mlevitsk@redhat.com> <20200527011344.GB31696@linux.intel.com> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.36.2 (3.36.2-1.fc32) MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2020-05-26 at 18:13 -0700, Sean Christopherson wrote: > On Sat, May 23, 2020 at 07:14:53PM +0300, Maxim Levitsky wrote: > > On my AMD machine I noticed that I can't start any nested guests, > > because nested KVM (everything from master git branches) complains > > that it can't find msr MSR_IA32_UMWAIT_CONTROL which my system > > doesn't support > > at all anyway. > > > > I traced it to the recently added UMWAIT support to qemu and kvm. > > The kvm portion exposed the new MSR in KVM_GET_MSR_INDEX_LIST > > without > > checking that it the underlying feature is supported in CPUID. > > It happened to work when non nested because as a precation kvm, > > tries to read each MSR on host before adding it to that list, > > and when read gets a #GP it ignores it. > > > > When running nested, the L1 hypervisor can be set to ignore unknown > > msr read/writes (I need this for some other guests), thus this > > safety > > check doesn't work anymore. > > > > V2: * added a patch to setup correctly the X86_FEATURE_WAITPKG kvm > > capability > > * dropped the cosmetic fix patch as it is now fixed in kvm/queue > > > > Best regards, > > Maxim Levitsky > > > > Maxim Levitsky (2): > > kvm/x86/vmx: enable X86_FEATURE_WAITPKG in KVM capabilities > > kvm/x86: don't expose MSR_IA32_UMWAIT_CONTROL unconditionally > > Standard scoping in the shortlog is "KVM: VMX:" and "KVM: x86:". Noted and I will use it from now on. Thanks! Best regards, Maxim Levitsky > > > arch/x86/kvm/vmx/vmx.c | 3 +++ > > arch/x86/kvm/x86.c | 4 ++++ > > 2 files changed, 7 insertions(+) > > > > -- > > 2.26.2 > > > >