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: Sun, 21 Sep 2008 18:57:32 +0200 Message-ID: <48D67CFC.5030700@web.de> References: <48D392F2.300@siemens.com> <48D39555.4020106@siemens.com> <20080921143144.GB27089@minantech.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enigE3A26D54BCA7E16833BE3435" Cc: kvm-devel , "Yang, Sheng" , Avi Kivity To: Gleb Natapov Return-path: Received: from fmmailgate03.web.de ([217.72.192.234]:32796 "EHLO fmmailgate03.web.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751940AbYIUQ5j (ORCPT ); Sun, 21 Sep 2008 12:57:39 -0400 In-Reply-To: <20080921143144.GB27089@minantech.com> Sender: kvm-owner@vger.kernel.org List-ID: This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enigE3A26D54BCA7E16833BE3435 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Gleb Natapov wrote: > Hi Jan, >=20 > 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; >> + } >=20 > Windows2003 sets NMI entry in IDT as a task gate (0x5) during hibernati= on and this check > prevents it from shutting down itself. It hangs in "It is save to turn > your computer now" screen. Grmbl, what a weird guest... Is this a regression of this patch because NMIs were considered broken by Windows on that host CPU so far? > 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. I guess (hope) Windows will switch to an NMI task which has IRQs disabled (!(TSS.EFLAGS & IF)), so this may become another check for those weird task users. Waiting on the next IRQ window for NMI injection should work equally well with tasks, given they disable IRQs properly. Thanks for testing! Jan PS: There are more issues in my v1 series, update will follow tomorrow. --------------enigE3A26D54BCA7E16833BE3435 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 iEYEARECAAYFAkjWfQAACgkQniDOoMHTA+lVTwCfVfNFXl29o2jpX3SXILraOLNs AoYAn0CHOx7UDODRDduW9Ul62URNA2rQ =d39m -----END PGP SIGNATURE----- --------------enigE3A26D54BCA7E16833BE3435--