In ICL platform, it is easy to hit bootup failure with panic
in thermal interrupt handler during early bootup stage.
Such issue makes my platform almost can not boot up with
latest kernel code.
The call stack is like:
kernel BUG at kernel/timer/timer.c:1152!
Call Trace:
__queue_delayed_work
queue_delayed_work_on
therm_throt_process
intel_thermal_interrupt
...
When one CPU is up, the irq is enabled prior to CPU UP
notification which will then initialize therm_worker.
Such race will cause the posssibility that interrupt
handler therm_throt_process() accesses uninitialized
therm_work, then system hit panic at very early bootup
stage.
In my ICL platform, it can be reproduced in several times
of reboot stress. With this fix, the system keeps alive
for more than 200 times of reboot stress.
V2: Boris shares a good suggestion that we can moving the
interrupt unmasking at the end of therm_work initialization.
Signed-off-by: Chuansheng Liu <[email protected]>
---
arch/x86/kernel/cpu/mce/therm_throt.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)
diff --git a/arch/x86/kernel/cpu/mce/therm_throt.c b/arch/x86/kernel/cpu/mce/therm_throt.c
index b38010b541d6..528b85664b46 100644
--- a/arch/x86/kernel/cpu/mce/therm_throt.c
+++ b/arch/x86/kernel/cpu/mce/therm_throt.c
@@ -467,6 +467,7 @@ static int thermal_throttle_online(unsigned int cpu)
{
struct thermal_state *state = &per_cpu(thermal_state, cpu);
struct device *dev = get_cpu_device(cpu);
+ u32 l;
state->package_throttle.level = PACKAGE_LEVEL;
state->core_throttle.level = CORE_LEVEL;
@@ -474,6 +475,12 @@ static int thermal_throttle_online(unsigned int cpu)
INIT_DELAYED_WORK(&state->package_throttle.therm_work, throttle_active_work);
INIT_DELAYED_WORK(&state->core_throttle.therm_work, throttle_active_work);
+ /* Unmask the thermal vector after
+ * therm_works are initialized.
+ */
+ l = apic_read(APIC_LVTTHMR);
+ apic_write(APIC_LVTTHMR, l & ~APIC_LVT_MASKED);
+
return thermal_throttle_add_dev(dev, cpu);
}
@@ -722,10 +729,6 @@ void intel_init_thermal(struct cpuinfo_x86 *c)
rdmsr(MSR_IA32_MISC_ENABLE, l, h);
wrmsr(MSR_IA32_MISC_ENABLE, l | MSR_IA32_MISC_ENABLE_TM1, h);
- /* Unmask the thermal vector: */
- l = apic_read(APIC_LVTTHMR);
- apic_write(APIC_LVTTHMR, l & ~APIC_LVT_MASKED);
-
pr_info_once("CPU0: Thermal monitoring enabled (%s)\n",
tm2 ? "TM2" : "TM1");
--
2.17.1
On Tue, Jan 07, 2020 at 12:41:16AM +0000, Chuansheng Liu wrote:
> In my ICL platform, it can be reproduced in several times
> of reboot stress. With this fix, the system keeps alive
> for more than 200 times of reboot stress.
>
> V2: Boris shares a good suggestion that we can moving the
> interrupt unmasking at the end of therm_work initialization.
>
> Signed-off-by: Chuansheng Liu <[email protected]>
Looks good to me:
Acked-by: Tony Luck <[email protected]>
On Fri, Jan 10, 2020 at 10:29:29AM -0800, Luck, Tony wrote:
> On Tue, Jan 07, 2020 at 12:41:16AM +0000, Chuansheng Liu wrote:
> > In my ICL platform, it can be reproduced in several times
> > of reboot stress. With this fix, the system keeps alive
> > for more than 200 times of reboot stress.
> >
> > V2: Boris shares a good suggestion that we can moving the
> > interrupt unmasking at the end of therm_work initialization.
> >
> > Signed-off-by: Chuansheng Liu <[email protected]>
>
> Looks good to me:
>
> Acked-by: Tony Luck <[email protected]>
Thx.
This "ICL platform" - whatever that is - is this shipping already so
that this qualifies for stable@ or can it go the normal path?
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
> -----Original Message-----
> From: Borislav Petkov <[email protected]>
> Sent: Monday, January 13, 2020 5:05 PM
> To: Luck, Tony <[email protected]>
> Cc: Liu, Chuansheng <[email protected]>; linux-
> [email protected]; [email protected]; [email protected];
> [email protected]
> Subject: Re: [PATCH v2] x86/mce/therm_throt: Fix the access of uninitialized
> therm_work
>
> On Fri, Jan 10, 2020 at 10:29:29AM -0800, Luck, Tony wrote:
> > On Tue, Jan 07, 2020 at 12:41:16AM +0000, Chuansheng Liu wrote:
> > > In my ICL platform, it can be reproduced in several times
> > > of reboot stress. With this fix, the system keeps alive
> > > for more than 200 times of reboot stress.
> > >
> > > V2: Boris shares a good suggestion that we can moving the
> > > interrupt unmasking at the end of therm_work initialization.
> > >
> > > Signed-off-by: Chuansheng Liu <[email protected]>
> >
> > Looks good to me:
> >
> > Acked-by: Tony Luck <[email protected]>
>
> Thx.
>
> This "ICL platform" - whatever that is - is this shipping already so
I just can say ICL(icelake) is shipped platform, I reproduced this issue
in one laptop.
The following commit has been merged into the ras/urgent branch of tip:
Commit-ID: 978370956d2046b19313659ce65ed12d5b996626
Gitweb: https://git.kernel.org/tip/978370956d2046b19313659ce65ed12d5b996626
Author: Chuansheng Liu <[email protected]>
AuthorDate: Tue, 07 Jan 2020 00:41:16
Committer: Borislav Petkov <[email protected]>
CommitterDate: Wed, 15 Jan 2020 11:31:33 +01:00
x86/mce/therm_throt: Do not access uninitialized therm_work
It is relatively easy to trigger the following boot splat on an Ice Lake
client platform. The call stack is like:
kernel BUG at kernel/timer/timer.c:1152!
Call Trace:
__queue_delayed_work
queue_delayed_work_on
therm_throt_process
intel_thermal_interrupt
...
The reason is that a CPU's thermal interrupt is enabled prior to
executing its hotplug onlining callback which will initialize the
throttling workqueues.
Such a race can lead to therm_throt_process() accessing an uninitialized
therm_work, leading to the above BUG at a very early bootup stage.
Therefore, unmask the thermal interrupt vector only after having setup
the workqueues completely.
[ bp: Heavily massage commit message and correct comment formatting. ]
Fixes: f6656208f04e ("x86/mce/therm_throt: Optimize notifications of thermal throttle")
Signed-off-by: Chuansheng Liu <[email protected]>
Signed-off-by: Borislav Petkov <[email protected]>
Acked-by: Tony Luck <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]
---
arch/x86/kernel/cpu/mce/therm_throt.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/arch/x86/kernel/cpu/mce/therm_throt.c b/arch/x86/kernel/cpu/mce/therm_throt.c
index b38010b..6c3e1c9 100644
--- a/arch/x86/kernel/cpu/mce/therm_throt.c
+++ b/arch/x86/kernel/cpu/mce/therm_throt.c
@@ -467,6 +467,7 @@ static int thermal_throttle_online(unsigned int cpu)
{
struct thermal_state *state = &per_cpu(thermal_state, cpu);
struct device *dev = get_cpu_device(cpu);
+ u32 l;
state->package_throttle.level = PACKAGE_LEVEL;
state->core_throttle.level = CORE_LEVEL;
@@ -474,6 +475,10 @@ static int thermal_throttle_online(unsigned int cpu)
INIT_DELAYED_WORK(&state->package_throttle.therm_work, throttle_active_work);
INIT_DELAYED_WORK(&state->core_throttle.therm_work, throttle_active_work);
+ /* Unmask the thermal vector after the above workqueues are initialized. */
+ l = apic_read(APIC_LVTTHMR);
+ apic_write(APIC_LVTTHMR, l & ~APIC_LVT_MASKED);
+
return thermal_throttle_add_dev(dev, cpu);
}
@@ -722,10 +727,6 @@ void intel_init_thermal(struct cpuinfo_x86 *c)
rdmsr(MSR_IA32_MISC_ENABLE, l, h);
wrmsr(MSR_IA32_MISC_ENABLE, l | MSR_IA32_MISC_ENABLE_TM1, h);
- /* Unmask the thermal vector: */
- l = apic_read(APIC_LVTTHMR);
- apic_write(APIC_LVTTHMR, l & ~APIC_LVT_MASKED);
-
pr_info_once("CPU0: Thermal monitoring enabled (%s)\n",
tm2 ? "TM2" : "TM1");