From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kashyap Chamarthy Subject: nSVM: Booting L2 results in L1 hang and a "skip_emulated_instruction" Date: Wed, 11 Feb 2015 19:12:07 +0100 Message-ID: <20150211181207.GM8956@tesla.redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: jan.kiszka@siemens.com, pbonzini@redhat.com To: kvm@vger.kernel.org Return-path: Received: from mx1.redhat.com ([209.132.183.28]:41023 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752819AbbBKSMP (ORCPT ); Wed, 11 Feb 2015 13:12:15 -0500 Content-Disposition: inline Sender: kvm-owner@vger.kernel.org List-ID: Hi, This was tested with kernel-3.19.0-1.fc22) and QEMU (qemu-2.2.0-5.fc22) on L0 & L1. Description ----------- Inside L1, boot a nested KVM guest (L2) . Instead of a full blown guest, let's use `qemu-sanity-check` with KVM: $ qemu-sanity-check --accel=kvm Wwich gives you this CLI (run from a different shell), that confirms that the L2 guest is indeed running on KVM (and not TCG): $ ps -ef | grep -i qemu root 763 762 35 11:49 ttyS0 00:00:00 qemu-system-x86_64 -nographic -nodefconfig -nodefaults -machine accel=kvm -no-reboot -serial file:/tmp/tmp.rl3naPaCkZ.out -kernel /boot/vmlinuz-3.19.0-1.fc21.x86_64 -initrd /usr/lib64/qemu-sanity-check/initrd -append console=ttyS0 oops=panic panic=-1 Which results in: (a) L1 (guest hypervisor) completely hangs and is unresponsive. But when I query libvirt, (`virsh list`) the guest is still reported as 'running' (b) On L0, I notice a ton of these messages: skip_emulated_instruction: ip 0xffec next 0xffffffff8105e964 I can get `dmesg`, `dmidecode` , `x86info -a` on L0 and L1 if it helps in narrowing down the issue. Related bug and reproducer details ---------------------------------- https://bugzilla.redhat.com/show_bug.cgi?id=1191665 -- Nested KVM with AMD: L2 (nested guest) fails with "divide error: 0000 [#1] SMP" -- /kashyap