From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jan Kiszka Subject: Re: [PATCH] KVM: x86: Avoid busy loops over uninjectable pending APIC timers Date: Sun, 28 Apr 2013 12:20:12 +0200 Message-ID: <517CF7DC.7010109@web.de> References: <5144DAC3.7080401@web.de> <20130317084705.GC11223@redhat.com> <517CF6A9.4090500@web.de> <20130428101905.GH30504@redhat.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="----enig2SFQMWNIIVWVJGQPGEERU" Cc: Marcelo Tosatti , kvm To: Gleb Natapov Return-path: Received: from mout.web.de ([212.227.15.3]:60702 "EHLO mout.web.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752155Ab3D1KUU (ORCPT ); Sun, 28 Apr 2013 06:20:20 -0400 In-Reply-To: <20130428101905.GH30504@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: This is an OpenPGP/MIME signed message (RFC 4880 and 3156) ------enig2SFQMWNIIVWVJGQPGEERU Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable On 2013-04-28 12:19, Gleb Natapov wrote: > On Sun, Apr 28, 2013 at 12:15:05PM +0200, Jan Kiszka wrote: >> On 2013-03-17 09:47, Gleb Natapov wrote: >>> On Sat, Mar 16, 2013 at 09:49:07PM +0100, Jan Kiszka wrote: >>>> From: Jan Kiszka >>>> >>>> If the guest didn't take the last APIC timer interrupt yet and gener= ates >>>> another one on top, e.g. via periodic mode, we do not block the VCPU= >>>> even if the guest state is halted. The reason is that >>>> apic_has_pending_timer continues to return a non-zero value. >>>> >>>> Fix this busy loop by taking the IRR content for the LVT vector in >>>> apic_has_pending_timer into account. >>>> >>> Just drop coalescing tacking for lapic interrupt. After posted interr= upt >>> will be merged __apic_accept_irq() will not longer return coalescing >>> information, so the code will be dead anyway. >> >> If I understood the follow-up discussion correctly, we aren't dropping= >> de-coalescing support yet. So how to proceed with this fix here? >> > We do. It does not work if you run on CPU with apicv support already. But isn't the code still there and working when apicv is absent? Jan ------enig2SFQMWNIIVWVJGQPGEERU Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.16 (GNU/Linux) Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iEYEARECAAYFAlF899wACgkQitSsb3rl5xSa/ACgxnYwcN92KZ0s6jidaAm4Isz7 4i8AoNt1mhObcnImSJdBLuVSeKRB9IbM =zJ9l -----END PGP SIGNATURE----- ------enig2SFQMWNIIVWVJGQPGEERU--