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Message-ID: <52C6F3B4.3050904@gmail.com>
Date: Fri, 03 Jan 2014 09:30:28 -0800
From: Dirk Brandewie <dirk.brandewie@...il.com>
To: "Rafael J. Wysocki" <rjw@...ysocki.net>,
Kashyap Chamarthy <kchamart@...hat.com>
CC: Gleb Natapov <gleb@...nel.org>,
Josh Boyer <jwboyer@...oraproject.org>,
One Thousand Gnomes <gnomes@...rguk.ukuu.org.uk>,
Viresh Kumar <viresh.kumar@...aro.org>,
"cpufreq@...r.kernel.org" <cpufreq@...r.kernel.org>,
Linux PM list <linux-pm@...r.kernel.org>,
"Linux-Kernel@...r. Kernel. Org" <linux-kernel@...r.kernel.org>,
"Richard W.M. Jones" <rjones@...hat.com>
Subject: Re: intel_pstate divide error with v3.13-rc4-256-gb7000ad
Hi All,
Sorry for being late to the party but I just got back from vacation.
There is something deeply wrong here. We should have never gotten to
intel_pstate_init_cpu(). The VM had to have returned value from the read
of the max pstate at driver init time and 0 when the CPU was being brought up.
intel_pstate_msrs_not_valid() was added to solve this issue early on
if I remember correctly it was Josh that reported it then. Is there
a definative way to detect whether we are running in a VM?
Can some one tell me how the nested environment differs in regards to
reading MSRs?
TIA
--Dirk
On 12/30/2013 06:07 PM, Rafael J. Wysocki wrote:
>>> ---
>>> drivers/cpufreq/intel_pstate.c | 5 +++++
>>> 1 file changed, 5 insertions(+)
>>>
>>> Index: linux-pm/drivers/cpufreq/intel_pstate.c
>>> ===================================================================
>>> --- linux-pm.orig/drivers/cpufreq/intel_pstate.c
>>> +++ linux-pm/drivers/cpufreq/intel_pstate.c
>>> @@ -614,6 +614,11 @@ static int intel_pstate_init_cpu(unsigne
>>> cpu = all_cpu_data[cpunum];
>>>
>>> intel_pstate_get_cpu_pstates(cpu);
>>> + if (!cpu->pstate.current_pstate) {
>>> + all_cpu_data[cpunum] = NULL;
>>> + kfree(cpu);
>>> + return -ENODATA;
>>> + }
>>>
>>> cpu->cpu = cpunum;
>>>
>>>
>>
>>
>> Thanks Rafel, I can confirm this patch helps.
>
> Awesome, thanks!
>
> Below is an official version with a changelog. I'll queue it up as a fix
> for 3.13.
>
> Thanks,
> Rafael
>
>
> ---
> From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> Subject: intel_pstate: Fail initialization if P-state information is missing
>
> If pstate.current_pstate is 0 after the initial
> intel_pstate_get_cpu_pstates(), this means that we were unable to
> obtain any useful P-state information and there is no reason to
> continue, so free memory and return an error in that case.
>
> This fixes the following divide error occuring in a nested KVM
> guest:
>
> Intel P-state driver initializing.
> Intel pstate controlling: cpu 0
> cpufreq: __cpufreq_add_dev: ->get() failed
> divide error: 0000 [#1] SMP
> Modules linked in:
> CPU: 0 PID: 1 Comm: swapper/0 Not tainted 3.13.0-0.rc4.git5.1.fc21.x86_64 #1
> Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
> task: ffff88001ea20000 ti: ffff88001e9bc000 task.ti: ffff88001e9bc000
> RIP: 0010:[<ffffffff815c551d>] [<ffffffff815c551d>] intel_pstate_timer_func+0x11d/0x2b0
> RSP: 0000:ffff88001ee03e18 EFLAGS: 00010246
> RAX: 0000000000000000 RBX: ffff88001a454348 RCX: 0000000000006100
> RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
> RBP: ffff88001ee03e38 R08: 0000000000000000 R09: 0000000000000000
> R10: ffff88001ea20000 R11: 0000000000000000 R12: 00000c0a1ea20000
> R13: 1ea200001ea20000 R14: ffffffff815c5400 R15: ffff88001a454348
> FS: 0000000000000000(0000) GS:ffff88001ee00000(0000) knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b
> CR2: 0000000000000000 CR3: 0000000001c0c000 CR4: 00000000000006f0
> Stack:
> fffffffb1a454390 ffffffff821a4500 ffff88001a454390 0000000000000100
> ffff88001ee03ea8 ffffffff81083e9a ffffffff81083e15 ffffffff82d5ed40
> ffffffff8258cc60 0000000000000000 ffffffff81ac39de 0000000000000000
> Call Trace:
> <IRQ>
> [<ffffffff81083e9a>] call_timer_fn+0x8a/0x310
> [<ffffffff81083e15>] ? call_timer_fn+0x5/0x310
> [<ffffffff815c5400>] ? pid_param_set+0x130/0x130
> [<ffffffff81084354>] run_timer_softirq+0x234/0x380
> [<ffffffff8107aee4>] __do_softirq+0x104/0x430
> [<ffffffff8107b5fd>] irq_exit+0xcd/0xe0
> [<ffffffff81770645>] smp_apic_timer_interrupt+0x45/0x60
> [<ffffffff8176efb2>] apic_timer_interrupt+0x72/0x80
> <EOI>
> [<ffffffff810e15cd>] ? vprintk_emit+0x1dd/0x5e0
> [<ffffffff81757719>] printk+0x67/0x69
> [<ffffffff815c1493>] __cpufreq_add_dev.isra.13+0x883/0x8d0
> [<ffffffff815c14f0>] cpufreq_add_dev+0x10/0x20
> [<ffffffff814a14d1>] subsys_interface_register+0xb1/0xf0
> [<ffffffff815bf5cf>] cpufreq_register_driver+0x9f/0x210
> [<ffffffff81fb19af>] intel_pstate_init+0x27d/0x3be
> [<ffffffff81761e3e>] ? mutex_unlock+0xe/0x10
> [<ffffffff81fb1732>] ? cpufreq_gov_dbs_init+0x12/0x12
> [<ffffffff8100214a>] do_one_initcall+0xfa/0x1b0
> [<ffffffff8109dbf5>] ? parse_args+0x225/0x3f0
> [<ffffffff81f64193>] kernel_init_freeable+0x1fc/0x287
> [<ffffffff81f638d0>] ? do_early_param+0x88/0x88
> [<ffffffff8174b530>] ? rest_init+0x150/0x150
> [<ffffffff8174b53e>] kernel_init+0xe/0x130
> [<ffffffff8176e27c>] ret_from_fork+0x7c/0xb0
> [<ffffffff8174b530>] ? rest_init+0x150/0x150
> 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
> RIP [<ffffffff815c551d>] intel_pstate_timer_func+0x11d/0x2b0
> RSP <ffff88001ee03e18>
> ---[ end trace f166110ed22cc37a ]---
> Kernel panic - not syncing: Fatal exception in interrupt
>
> Reported-and-tested-by: Kashyap Chamarthy <kchamart@...hat.com>
> Cc: Josh Boyer <jwboyer@...oraproject.org>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> ---
> drivers/cpufreq/intel_pstate.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> Index: linux-pm/drivers/cpufreq/intel_pstate.c
> ===================================================================
> --- linux-pm.orig/drivers/cpufreq/intel_pstate.c
> +++ linux-pm/drivers/cpufreq/intel_pstate.c
> @@ -614,6 +614,11 @@ static int intel_pstate_init_cpu(unsigne
> cpu = all_cpu_data[cpunum];
>
> intel_pstate_get_cpu_pstates(cpu);
> + if (!cpu->pstate.current_pstate) {
> + all_cpu_data[cpunum] = NULL;
> + kfree(cpu);
> + return -ENODATA;
> + }
>
> cpu->cpu = cpunum;
>
>
--
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