Package: xen-hypervisor-4.1-amd64 Version: 4.1.3-7 Severity: important Tags: patch
Dear Maintainer, The PMU may be enabled on the Dom0 although the needed MSRs are not accessible, causing at least major noise on the xen messages ring buffer. I suspect there might also be a performance decrease, because the MSR write is trapped by Xen. Once the PC is in that state, a reboot won't help. This bug is fixed in Xen upstream: http://xenbits.xen.org/gitweb/?p=xen.git;a=commit;h=cabea9d59f1783167a79fa7a550ced04b3506f3c I've successfully tested this patch on the debian kernel from wheezy. How to reproduce: - boot bare metal kernel (that is, no xen hypervisor) - (re)boot dom0 with xen This results in the following kernel warning: [ 0.016036] ------------[ cut here ]------------ [ 0.016070] WARNING: at /build/buildd-linux_3.2.35-2-amd64-v9djlH/linux-3.2.35/arch/x86/xen/enlighten.c:738 init_hw_perf_events+0x246/0x3e1() [ 0.016107] Hardware name: MS-7368 [ 0.016135] Modules linked in: [ 0.016189] Pid: 1, comm: swapper/0 Not tainted 3.2.0-4-amd64 #1 Debian 3.2.35-2 [ 0.016224] Call Trace: [ 0.016257] [<ffffffff81046a75>] ? warn_slowpath_common+0x78/0x8c [ 0.016289] [<ffffffff816b2f72>] ? init_hw_perf_events+0x246/0x3e1 [ 0.016319] [<ffffffff816b2d2c>] ? check_bugs+0x2b/0x2b [ 0.016351] [<ffffffff81002085>] ? do_one_initcall+0x75/0x12c [ 0.016383] [<ffffffff816abbcb>] ? kernel_init+0x8d/0x152 [ 0.016414] [<ffffffff81354174>] ? kernel_thread_helper+0x4/0x10 [ 0.016447] [<ffffffff81352233>] ? int_ret_from_sys_call+0x7/0x1b [ 0.016479] [<ffffffff8134d37c>] ? retint_restore_args+0x5/0x6 [ 0.016509] [<ffffffff81354170>] ? gs_change+0x13/0x13 [ 0.016545] ---[ end trace 4fbe30a09b2591f0 ]--- [ 0.016576] ... version: 0 [ 0.016605] ... bit width: 48 [ 0.016633] ... generic registers: 4 [ 0.016662] ... value mask: 0000ffffffffffff [ 0.016691] ... max period: 00007fffffffffff [ 0.016721] ... fixed-purpose events: 0 [ 0.016749] ... event mask: 000000000000000f [ 0.016971] NMI watchdog enabled, takes one hw-pmu counter. [ 0.017012] ------------[ cut here ]------------ and the following (repeating) output on the xen messages ring buffer: (XEN) printk: 28 messages suppressed. (XEN) traps.c:2488:d0 Domain attempted WRMSR 00000000c0010000 from 0x0000000000130076 to 0x0000000000530076. (XEN) printk: 52 messages suppressed. (XEN) traps.c:2488:d0 Domain attempted WRMSR 00000000c0010000 from 0x0000000000130076 to 0x0000000000530076. (XEN) printk: 27 messages suppressed. [..] -- System Information: Debian Release: 7.0 APT prefers testing APT policy: (500, 'testing') Architecture: amd64 (x86_64) Kernel: Linux 3.2.0-4-amd64 (SMP w/2 CPU cores) Locale: LANG=de_DE.UTF-8, LC_CTYPE=de_DE.UTF-8 (charmap=UTF-8) Shell: /bin/sh linked to /bin/dash xen-hypervisor-4.1-amd64 depends on no packages. Versions of packages xen-hypervisor-4.1-amd64 recommends: ii xen-utils-4.1 4.1.3-7 Versions of packages xen-hypervisor-4.1-amd64 suggests: ii xen-docs-4.1 4.1.3-7 -- no debconf information -- To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org