Hi All, We've had a report [1] that the pstate driver causes KVM guests to fail to boot because of a divide error. See the backtrace below. 4.839784] Intel P-state driver initializing. [ 4.859972] Intel pstate controlling: cpu 0 [ 4.867653] cpufreq: __cpufreq_add_dev: ->get() failed [ 4.877269] divide error: 0000 [#1] SMP [ 4.878127] Modules linked in: [ 4.878127] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 3.13.0-0.rc4.git5.1.fc21.x86_64 #1 [ 4.878127] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 [ 4.878127] task: ffff88001ea20000 ti: ffff88001e9bc000 task.ti: ffff88001e9bc000 [ 4.878127] RIP: 0010:[<ffffffff815c551d>] [<ffffffff815c551d>] intel_pstate_timer_func+0x11d/0x2b0 [ 4.878127] RSP: 0000:ffff88001ee03e18 EFLAGS: 00010246 [ 4.878127] RAX: 0000000000000000 RBX: ffff88001a454348 RCX: 0000000000006100 [ 4.878127] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 [ 4.878127] RBP: ffff88001ee03e38 R08: 0000000000000000 R09: 0000000000000000 [ 4.878127] R10: ffff88001ea20000 R11: 0000000000000000 R12: 00000c0a1ea20000 [ 4.878127] R13: 1ea200001ea20000 R14: ffffffff815c5400 R15: ffff88001a454348 [ 4.878127] FS: 0000000000000000(0000) GS:ffff88001ee00000(0000) knlGS:0000000000000000 [ 4.878127] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b [ 4.878127] CR2: 0000000000000000 CR3: 0000000001c0c000 CR4: 00000000000006f0 [ 4.878127] Stack: [ 4.878127] fffffffb1a454390 ffffffff821a4500 ffff88001a454390 0000000000000100 [ 4.878127] ffff88001ee03ea8 ffffffff81083e9a ffffffff81083e15 ffffffff82d5ed40 [ 4.878127] ffffffff8258cc60 0000000000000000 ffffffff81ac39de 0000000000000000 [ 4.878127] Call Trace: [ 4.878127] <IRQ> [ 4.878127] [<ffffffff81083e9a>] call_timer_fn+0x8a/0x310 [ 4.878127] [<ffffffff81083e15>] ? call_timer_fn+0x5/0x310 [ 4.878127] [<ffffffff815c5400>] ? pid_param_set+0x130/0x130 [ 4.878127] [<ffffffff81084354>] run_timer_softirq+0x234/0x380 [ 4.878127] [<ffffffff8107aee4>] __do_softirq+0x104/0x430 [ 4.878127] [<ffffffff8107b5fd>] irq_exit+0xcd/0xe0 [ 4.878127] [<ffffffff81770645>] smp_apic_timer_interrupt+0x45/0x60 [ 4.878127] [<ffffffff8176efb2>] apic_timer_interrupt+0x72/0x80 [ 4.878127] <EOI> [ 4.878127] [<ffffffff810e15cd>] ? vprintk_emit+0x1dd/0x5e0 [ 4.878127] [<ffffffff81757719>] printk+0x67/0x69 [ 4.878127] [<ffffffff815c1493>] __cpufreq_add_dev.isra.13+0x883/0x8d0 [ 4.878127] [<ffffffff815c14f0>] cpufreq_add_dev+0x10/0x20 [ 4.878127] [<ffffffff814a14d1>] subsys_interface_register+0xb1/0xf0 [ 4.878127] [<ffffffff815bf5cf>] cpufreq_register_driver+0x9f/0x210 [ 4.878127] [<ffffffff81fb19af>] intel_pstate_init+0x27d/0x3be [ 4.878127] [<ffffffff81761e3e>] ? mutex_unlock+0xe/0x10 [ 4.878127] [<ffffffff81fb1732>] ? cpufreq_gov_dbs_init+0x12/0x12 [ 4.878127] [<ffffffff8100214a>] do_one_initcall+0xfa/0x1b0 [ 4.878127] [<ffffffff8109dbf5>] ? parse_args+0x225/0x3f0 [ 4.878127] [<ffffffff81f64193>] kernel_init_freeable+0x1fc/0x287 [ 4.878127] [<ffffffff81f638d0>] ? do_early_param+0x88/0x88 [ 4.878127] [<ffffffff8174b530>] ? rest_init+0x150/0x150 [ 4.878127] [<ffffffff8174b53e>] kernel_init+0xe/0x130 [ 4.878127] [<ffffffff8176e27c>] ret_from_fork+0x7c/0xb0 [ 4.878127] [<ffffffff8174b530>] ? rest_init+0x150/0x150 [ 4.878127] Code: c1 e0 05 48 63 bc 03 10 01 00 00 48 63 83 d0 00 00 00 48 63 d6 48 c1 e2 08 c1 e1 08 4c 63 c2 48 c1 e0 08 48 98 48 c1 e0 08 48 99 <49> f7 f8 48 98 48 0f af f8 48 c1 ff 08 29 f9 89 ca c1 fa 1f 89 [ 4.878127] RIP [<ffffffff815c551d>] intel_pstate_timer_func+0x11d/0x2b0 [ 4.878127] RSP <ffff88001ee03e18> [ 5.438189] ---[ end trace f166110ed22cc37a ]--- [ 5.446428] Kernel panic - not syncing: Fatal exception in interrupt -- To unsubscribe from this list: send the line "unsubscribe cpufreq" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html