From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jan Kiszka Subject: Re: [RFC][PATCH] qemu-kvm: Introduce writeback scope for cpu_synchronize_state Date: Wed, 18 Nov 2009 10:50:00 +0100 Message-ID: <4B03C348.4010604@web.de> References: <4B018542.3020602@siemens.com> <4B01A487.3020808@redhat.com> <4B01C2B0.3000205@web.de> <4B02592C.6060004@redhat.com> <4B025B50.4070505@web.de> <4B0260D7.1060107@redhat.com> <4B026A03.4080600@web.de> <4B0298F0.3080007@redhat.com> <4B029FA8.5080205@web.de> <4B02A4FD.4010802@redhat.com> <4B02AF58.4010407@web.de> <4B02B252.5080207@redhat.com> <4B02D444.6080402@web.de> <4B02D659.2040004@redhat.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enigF84510FA8F19DFAC047C5E2B" Cc: Marcelo Tosatti , kvm , Gleb Natapov To: Avi Kivity Return-path: Received: from fmmailgate01.web.de ([217.72.192.221]:51810 "EHLO fmmailgate01.web.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755738AbZKRJuL (ORCPT ); Wed, 18 Nov 2009 04:50:11 -0500 In-Reply-To: <4B02D659.2040004@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enigF84510FA8F19DFAC047C5E2B Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Avi Kivity wrote: > On 11/17/2009 06:50 PM, Jan Kiszka wrote: >> >>> I think we're not on the same page here. As I see it, no interface >>> change is needed at all. >>> >>> It's true that existing kernels don't handle this properly, which is = why >>> I said I'm willing to treat it as a bug (and thus the -stable treatme= nt >>> etc.). I admit it's a stretch since this is not going to be trivial >>> (though I think less complex that you believe). >>> >>> Putting mp_state into the events structure is reasonable regardless o= f >>> this issue (and doable since we haven't pushed it to 2.6.33 yet). Bu= t I >>> want to understand why you think it's needed. >>> >>> =20 >> That wouldn't be required anymore with the "always queue" policy. >> =20 >=20 > It makes sense from a grouping point of view... maybe. >=20 >> But what would you queue at all? Only mp_state, nmi_pending and >> sipi_vector? >=20 > INIT, too. INIT should be handled by queuing up the next mp_state. BTW, as we do not inject mp_state changes from user space during runtime, the issue I saw with the current interface is not existing. We just need to add that queuing feature to asynchronous in-kernel mp_state changes, and we should be fine. Let's assume we will have such changes in future kernels: should qemu-kvm and qemu upstream also bother about older kernels and establish workarounds? Because then we need to find a cleaner approach than the current one, and my proposed patch comes into the game again. Jan --------------enigF84510FA8F19DFAC047C5E2B 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 iEYEARECAAYFAksDw1YACgkQitSsb3rl5xRBbgCg2SzD0hIEuuFAFi0Xi2kBYqTS YGUAn3L9Wi235fA8K3RF72KdjUQb3BXH =pfte -----END PGP SIGNATURE----- --------------enigF84510FA8F19DFAC047C5E2B--