From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jan Kiszka Subject: Re: qemu-kvm requires apic initialized before vcpu main loop Date: Wed, 09 Dec 2009 22:01:36 +0100 Message-ID: <4B201030.9030906@web.de> References: <20091209174654.GA28056@amt.cnet> <4B1FEB2A.3090906@siemens.com> <20091209192333.GC8739@redhat.com> <4B200412.5090005@web.de> <20091209205006.GD8739@redhat.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enigFEFA81F2A39A512748423D85" Cc: Marcelo Tosatti , Avi Kivity , Glauber de Oliveira Costa , kvm To: Gleb Natapov Return-path: Received: from fmmailgate02.web.de ([217.72.192.227]:44604 "EHLO fmmailgate02.web.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932078AbZLIVBf (ORCPT ); Wed, 9 Dec 2009 16:01:35 -0500 In-Reply-To: <20091209205006.GD8739@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enigFEFA81F2A39A512748423D85 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Gleb Natapov wrote: > On Wed, Dec 09, 2009 at 09:09:54PM +0100, Jan Kiszka wrote: >> Gleb Natapov wrote: >>> On Wed, Dec 09, 2009 at 07:23:38PM +0100, Jan Kiszka wrote: >>>> Marcelo Tosatti wrote: >>>>> Otherwise a zero apic base is loaded into KVM, which results >>>>> in interrupts being lost until a proper apic base with enabled=20 >>>>> bit set is loaded. >>>>> >>>>> Fixes WinXP migration in qemu-kvm origin/next. >>>>> >>>>> Signed-off-by: Marcelo Tosatti >>>>> >>>>> diff --git a/hw/apic.c b/hw/apic.c >>>>> index 627ff98..45a4d2b 100644 >>>>> --- a/hw/apic.c >>>>> +++ b/hw/apic.c >>>>> @@ -1131,6 +1131,11 @@ int apic_init(CPUState *env) >>>>> vmstate_register(s->idx, &vmstate_apic, s); >>>>> qemu_register_reset(apic_reset, s); >>>>> =20 >>>>> + /* apic_reset must be called before the vcpu threads are initi= alized and load=20 >>>>> + * registers, in qemu-kvm. >>>>> + */ >>>>> + apic_reset(s); >>>>> + >>>>> local_apics[s->idx] =3D s; >>>>> return 0; >>>>> } >>>> Heals the issue I saw with Win2003 Server as well. >>>> >>>> Looks all a bit messy though. Hope we can establish a more regular a= nd >>>> less fragile model on the midterm. I wonder if it wouldn't be better= to >>>> do write-back of the local APIC state along with the register state = on >>>> vmrun (and only there!). The same would apply to things like mpstate= , >>> Write back of mp state there is a bug and introduce races. Do write b= ack >>> of the whole APIC state there looks like a recipe for disaster. >> Please read the full suggestion: We will only write-back if we were >> going through a reset or vmload before. That removes the ugly kvm hook= s >> from generic code and ensures proper ordering /wrt other write-backs. >> IMHO, anything else will continue to cause headache like the above to = us. >> > We can't postpone APIC loading till vmrun. This will race with > devices/other vcpus sending interrupts to the vcpu. APIC state of all > vcpus should be up-to-date _before_ any vcpu or main loop starts > running. Simple to solve, just add another write-back point: vm_start. Jan --------------enigFEFA81F2A39A512748423D85 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 iEYEARECAAYFAksgEDMACgkQitSsb3rl5xQXZQCfTWaifC4WFr9xVZ4EkAVle6y4 m/kAoNbFzjICdrit4q3azgX8atpMIDIG =v5u+ -----END PGP SIGNATURE----- --------------enigFEFA81F2A39A512748423D85--