From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jan Kiszka Subject: Re: [PATCH 8/9] VMX: work around lacking VNMI support Date: Mon, 22 Sep 2008 09:19:27 +0200 Message-ID: <48D746FF.9000609@web.de> References: <48D392F2.300@siemens.com> <48D39555.4020106@siemens.com> <20080921143144.GB27089@minantech.com> <48D67CFC.5030700@web.de> <20080922064155.GC27089@minantech.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enigBEAC408038B43A25A1244CBE" Cc: kvm-devel , "Yang, Sheng" , Avi Kivity To: Gleb Natapov Return-path: Received: from fmmailgate03.web.de ([217.72.192.234]:39532 "EHLO fmmailgate03.web.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750764AbYIVHTd (ORCPT ); Mon, 22 Sep 2008 03:19:33 -0400 In-Reply-To: <20080922064155.GC27089@minantech.com> Sender: kvm-owner@vger.kernel.org List-ID: This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enigBEAC408038B43A25A1244CBE Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Gleb Natapov wrote: > On Sun, Sep 21, 2008 at 06:57:32PM +0200, Jan Kiszka wrote: >> Gleb Natapov wrote: >>> Hi Jan, >>> >>> On Fri, Sep 19, 2008 at 02:04:37PM +0200, Jan Kiszka wrote: >>>> static void vmx_inject_irq(struct kvm_vcpu *vcpu, int irq) >>>> { >>>> struct vcpu_vmx *vmx =3D to_vmx(vcpu); >>>> @@ -2356,6 +2384,29 @@ static void vmx_inject_nmi(struct kvm_vc >>>> { >>>> struct vcpu_vmx *vmx =3D to_vmx(vcpu); >>>> =20 >>>> + if (!cpu_has_virtual_nmis()) { >>>> + int desc_size =3D is_long_mode(vcpu) ? 16 : 8; >>>> + struct descriptor_table dt; >>>> + gpa_t gpa; >>>> + u64 desc; >>>> + >>>> + /* >>>> + * Deny delivery if the NMI will not be handled by an >>>> + * interrupt gate (workaround depends on IRQ masking). >>>> + */ >>>> + vmx_get_idt(vcpu, &dt); >>>> + if (!vcpu->arch.rmode.active && dt.limit >>>> + >=3D desc_size * (NMI_VECTOR + 1) - 1) { >>>> + gpa =3D vcpu->arch.mmu.gva_to_gpa(vcpu, >>>> + dt.base + desc_size * NMI_VECTOR); >>>> + if (kvm_read_guest(vcpu->kvm, gpa, &desc, 8) =3D=3D 0 >>>> + && ((desc >> 40) & 0x7) !=3D 0x6) >>>> + return; >>>> + } >>> Windows2003 sets NMI entry in IDT as a task gate (0x5) during hiberna= tion and this check >>> prevents it from shutting down itself. It hangs in "It is save to tur= n >>> your computer now" screen. >> Grmbl, what a weird guest... > This is a known trick that some OSes use. OK. Out of curiosity: What is that trick precisely? >=20 >> Is this a regression of this patch because NMIs were considered broken= >> by Windows on that host CPU so far? >> > Nope. This is not a regression. Hibernation hangs in the same place wit= h > the current git on this machine. It works on newer CPUs. >=20 >=20 >>> If I replace this part by: >>> if(vmx->soft_vnmi_blocked) >>> return; >>> It shut itself down properly. >> OK, but that almost always evaluates to false here. > Without this check guest BSODs. CPU 0 send two NMI in a row to CPU 1 an= d > if second one is accepted something goes wrong. That should have been caught at the caller site of vmx_inject_nmi already, having to catch it here is an indication of a deeper problem. Are you sure the NMIs are sent by CPU (i.e. kvm_inject_nmi is called twice)? Maybe it is a bug I fixed meanwhile, an updated series goes out later this morning. Jan --------------enigBEAC408038B43A25A1244CBE Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.9 (GNU/Linux) Comment: Using GnuPG with SUSE - http://enigmail.mozdev.org iEYEARECAAYFAkjXRwIACgkQniDOoMHTA+nrtQCfSJPPMhMCKHmIkhpxkEkjhWMx KiAAoIEcLzlNlVqugWM+oGDbHGg9+eZ5 =cjKO -----END PGP SIGNATURE----- --------------enigBEAC408038B43A25A1244CBE--