From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stefan Bader Subject: nVMX regression v3.13+, bisected Date: Wed, 26 Feb 2014 20:43:40 +0100 Message-ID: <530E43EC.7000600@canonical.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="UWukSgBCjcoSr7RptfnFqWEEMRuu3XsqA" Cc: Anthoine Bourgeois , Paolo Bonzini To: kvm@vger.kernel.org Return-path: Received: from youngberry.canonical.com ([91.189.89.112]:53087 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751439AbaBZTno (ORCPT ); Wed, 26 Feb 2014 14:43:44 -0500 Sender: kvm-owner@vger.kernel.org List-ID: This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --UWukSgBCjcoSr7RptfnFqWEEMRuu3XsqA Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: quoted-printable Hi, I was looking at a bug report[1] about a regression on nested VMX that st= arted with kernel v3.13 (same issue still existed with v3.14-rc4). The problem = shows up when running a v3.13 kernel in L0 and then trying to launch a L2 (L1 w= as either a v3.2 kernel or v3.13, so seemed to have no immediate influence).= L2 is trying to boot a iso image and hangs before the isolinux boot loader disp= lays anything. A preinstalled hd image fails to boot, too. I bisected this and ended up on the following commit which, when reverted= made the launch work again: Author: Anthoine Bourgeois Date: Wed Nov 13 11:45:37 2013 +0100 kvm, vmx: Fix lazy FPU on nested guest If a nested guest does a NM fault but its CR0 doesn't contain the TS flag (because it was already cleared by the guest with L1 aid) then w= e have to activate FPU ourselves in L0 and then continue to L2. If TS f= lag is set then we fallback on the previous behavior, forward the fault t= o L1 if it asked for. Signed-off-by: Anthoine Bourgeois Signed-off-by: Paolo Bonzini The condition to exit to L0 seems to be according to what the description= says. Could it be that the handling in L0 is doing something wrong? -Stefan --UWukSgBCjcoSr7RptfnFqWEEMRuu3XsqA Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (GNU/Linux) Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iQIcBAEBCgAGBQJTDkPsAAoJEOhnXe7L7s6j8osQAIvWSa68twG1LyK/VAVfVxp2 qVJHos9q8jb5dE/j0Wz63p++ikT2sPF08JHodScZL8kcQzv3ToZpPtzglbC2Svim fiar/+JjPMSyg2dK4Adc6PKa2adPClcIyMX5ErvO7wJqZIUA+gTiMGFcuzi/60mF qkG06E7nIFz2HOn/vqPmnpUMRBWYa4eP+czIguLEr8jQkQkwC1e24p7n5sYdLnst Otd+nEroSU0cLX13v1+SlSyIKoTc4Lq3Xx00CCZUO7ItE2kpOIPZ9nkiLi0rux42 Wa2bSxyi3LG5EXP8mSWs0TGkI2MxAG/S0n6DfA1qxcdzZ14r5w9DA7oVpUbgdXaz iDjfr3Ke1plKNB05ClLJvYzRPK2E0arPSIkhmeucQzFnkXOmcvmWXbKYWfKRneZ1 yYoEsKrroFlsJkz2YUdvQG0cd1gXKAwmcNN6ywztB05XSJ00Vrbx0/mAUL/HyiiT zvCY1TmXTz8L6KJP8TQUNNKm1bSwu2isl68Imq+5M7tanFCUBky0P4sgLCJX3ruo HdeiyABi/XgR+lwfzAWXeGiM5ryr94jgAShLQdv0qgC7YawokbwEyhQc7Iw0l6mE hrwKNU7tjdvbQWBqx6nAMG2km7+qCc7Lir+jV7gXiNH2vb+UpPAPcjpLGg9eUx58 KxVMoxTswJ3gPVLbDrZK =80H2 -----END PGP SIGNATURE----- --UWukSgBCjcoSr7RptfnFqWEEMRuu3XsqA--