unchecked MSR access error in throttle_active_work()

unchecked MSR access error in throttle_active_work()

[Dominik Brodowski]

On most recent mainline kernels (such as 5.5-rc0 up to a6ed68d6468b), I see
the following output in dmesg during startup:

[   78.016676] unchecked MSR access error: WRMSR to 0x19c (tried to write 0x00000000880f3a80) at rIP: 0xffffffff84ab5742 (throttle_active_work+0xf2/0x230)
[   78.016686] Call Trace:
[   78.016694]  process_one_work+0x247/0x590
[   78.016703]  worker_thread+0x50/0x3b0
[   78.016710]  kthread+0x10a/0x140
[   78.016715]  ? process_one_work+0x590/0x590
[   78.016735]  ? kthread_park+0x90/0x90
[   78.016740]  ret_from_fork+0x3a/0x50

Any clues?

Thanks,
	Dominik

Re: unchecked MSR access error in throttle_active_work()

[Borislav Petkov]

On Thu, Nov 28, 2019 at 09:54:47AM +0100, Dominik Brodowski wrote:
> On most recent mainline kernels (such as 5.5-rc0 up to a6ed68d6468b), I see
> the following output in dmesg during startup:
> 
> [   78.016676] unchecked MSR access error: WRMSR to 0x19c (tried to write 0x00000000880f3a80) at rIP: 0xffffffff84ab5742 (throttle_active_work+0xf2/0x230)
> [   78.016686] Call Trace:
> [   78.016694]  process_one_work+0x247/0x590
> [   78.016703]  worker_thread+0x50/0x3b0
> [   78.016710]  kthread+0x10a/0x140
> [   78.016715]  ? process_one_work+0x590/0x590
> [   78.016735]  ? kthread_park+0x90/0x90
> [   78.016740]  ret_from_fork+0x3a/0x50
> 
> Any clues?

Most likely

f6656208f04e ("x86/mce/therm_throt: Optimize notifications of thermal throttle")

I guess we're missing some X86_FEATURE_ check for that MSR to exist.

Adding more people to Cc.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette

Re: unchecked MSR access error in throttle_active_work()

[Dominik Brodowski]

On Thu, Nov 28, 2019 at 10:44:19AM +0100, Borislav Petkov wrote:
> On Thu, Nov 28, 2019 at 09:54:47AM +0100, Dominik Brodowski wrote:
> > On most recent mainline kernels (such as 5.5-rc0 up to a6ed68d6468b), I see
> > the following output in dmesg during startup:
> > 
> > [   78.016676] unchecked MSR access error: WRMSR to 0x19c (tried to write 0x00000000880f3a80) at rIP: 0xffffffff84ab5742 (throttle_active_work+0xf2/0x230)
> > [   78.016686] Call Trace:
> > [   78.016694]  process_one_work+0x247/0x590
> > [   78.016703]  worker_thread+0x50/0x3b0
> > [   78.016710]  kthread+0x10a/0x140
> > [   78.016715]  ? process_one_work+0x590/0x590
> > [   78.016735]  ? kthread_park+0x90/0x90
> > [   78.016740]  ret_from_fork+0x3a/0x50
> > 
> > Any clues?
> 
> Most likely
> 
> f6656208f04e ("x86/mce/therm_throt: Optimize notifications of thermal throttle")
> 
> I guess we're missing some X86_FEATURE_ check for that MSR to exist.

Thanks. FWIW, it's a i7-8650U.

Best,
	Dominik

Re: unchecked MSR access error in throttle_active_work()

[Srinivas Pandruvada]

[-- Attachment #1: Type: text/plain, Size: 1167 bytes --]

On Thu, 2019-11-28 at 11:29 +0100, Dominik Brodowski wrote:
> On Thu, Nov 28, 2019 at 10:44:19AM +0100, Borislav Petkov wrote:
> > On Thu, Nov 28, 2019 at 09:54:47AM +0100, Dominik Brodowski wrote:
> > > On most recent mainline kernels (such as 5.5-rc0 up to
> > > a6ed68d6468b), I see
> > > the following output in dmesg during startup:
> > > 
> > > [   78.016676] unchecked MSR access error: WRMSR to 0x19c (tried
> > > to write 0x00000000880f3a80) at rIP: 0xffffffff84ab5742
> > > (throttle_active_work+0xf2/0x230)
> > > [   78.016686] Call Trace:
> > > [   78.016694]  process_one_work+0x247/0x590
> > > [   78.016703]  worker_thread+0x50/0x3b0
> > > [   78.016710]  kthread+0x10a/0x140
> > > [   78.016715]  ? process_one_work+0x590/0x590
> > > [   78.016735]  ? kthread_park+0x90/0x90
> > > [   78.016740]  ret_from_fork+0x3a/0x50
> > > 
> > > Any clues?
> > 
> > Most likely
> > 
> > f6656208f04e ("x86/mce/therm_throt: Optimize notifications of
> > thermal throttle")
> > 
> > I guess we're missing some X86_FEATURE_ check for that MSR to
> > exist.
> 
> Thanks. FWIW, it's a i7-8650U.
> 
Please try the attached patch. 

Thanks,
Srinivas

> Best,
> 	Dominik

[-- Attachment #2: 0001-x86-mce-therm_throt-Avoid-updating-RO-and-reserved-b.patch --]
[-- Type: text/x-patch, Size: 1706 bytes --]

From 945a0061aaf5164e7ac8ff6c0ee39be2c035c555 Mon Sep 17 00:00:00 2001
From: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Date: Thu, 28 Nov 2019 06:20:57 -0800
Subject: [PATCH] x86/mce/therm_throt: Avoid updating RO and reserved bits

While writing to MSR IA32_THERM_STATUS/IA32_PKG_THERM_STATUS avoid
writing 1 to read only and reserved fields. Updating some fields
generates exception.

Fixes: f6656208f04e ("x86/mce/therm_throt: Optimize notifications of thermal throttle")
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
---
 arch/x86/kernel/cpu/mce/therm_throt.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/cpu/mce/therm_throt.c b/arch/x86/kernel/cpu/mce/therm_throt.c
index d01e0da0163a..80be4a5ac303 100644
--- a/arch/x86/kernel/cpu/mce/therm_throt.c
+++ b/arch/x86/kernel/cpu/mce/therm_throt.c
@@ -195,17 +195,24 @@ static const struct attribute_group thermal_attr_group = {
 #define THERM_THROT_POLL_INTERVAL	HZ
 #define THERM_STATUS_PROCHOT_LOG	BIT(1)
 
+#define THERM_STATUS_CLEAR_CORE_MASK (BIT(1) | BIT(3) | BIT(5) | BIT(7) | BIT(9) | BIT(11) | BIT(13) | BIT(15))
+#define THERM_STATUS_CLEAR_PKG_MASK (BIT(1) | BIT(3) | BIT(5) | BIT(7) | BIT(9) | BIT(11))
+
 static void clear_therm_status_log(int level)
 {
 	int msr;
-	u64 msr_val;
+	u64 mask, msr_val;
 
-	if (level == CORE_LEVEL)
+	if (level == CORE_LEVEL) {
 		msr = MSR_IA32_THERM_STATUS;
-	else
+		mask = THERM_STATUS_CLEAR_CORE_MASK;
+	} else {
 		msr = MSR_IA32_PACKAGE_THERM_STATUS;
+		mask = THERM_STATUS_CLEAR_PKG_MASK;
+	}
 
 	rdmsrl(msr, msr_val);
+	msr_val &= mask;
 	wrmsrl(msr, msr_val & ~THERM_STATUS_PROCHOT_LOG);
 }
 
-- 
2.17.2

Re: unchecked MSR access error in throttle_active_work()

[Dominik Brodowski]

On Thu, Nov 28, 2019 at 06:51:42AM -0800, Srinivas Pandruvada wrote:
> On Thu, 2019-11-28 at 11:29 +0100, Dominik Brodowski wrote:
> > On Thu, Nov 28, 2019 at 10:44:19AM +0100, Borislav Petkov wrote:
> > > On Thu, Nov 28, 2019 at 09:54:47AM +0100, Dominik Brodowski wrote:
> > > > On most recent mainline kernels (such as 5.5-rc0 up to
> > > > a6ed68d6468b), I see
> > > > the following output in dmesg during startup:
> > > > 
> > > > [   78.016676] unchecked MSR access error: WRMSR to 0x19c (tried
> > > > to write 0x00000000880f3a80) at rIP: 0xffffffff84ab5742
> > > > (throttle_active_work+0xf2/0x230)
> > > > [   78.016686] Call Trace:
> > > > [   78.016694]  process_one_work+0x247/0x590
> > > > [   78.016703]  worker_thread+0x50/0x3b0
> > > > [   78.016710]  kthread+0x10a/0x140
> > > > [   78.016715]  ? process_one_work+0x590/0x590
> > > > [   78.016735]  ? kthread_park+0x90/0x90
> > > > [   78.016740]  ret_from_fork+0x3a/0x50
> > > > 
> > > > Any clues?
> > > 
> > > Most likely
> > > 
> > > f6656208f04e ("x86/mce/therm_throt: Optimize notifications of
> > > thermal throttle")
> > > 
> > > I guess we're missing some X86_FEATURE_ check for that MSR to
> > > exist.
> > 
> > Thanks. FWIW, it's a i7-8650U.
> > 
> Please try the attached patch. 

Seems to work fine now. Thanks!

	Dominik

Re: unchecked MSR access error in throttle_active_work()

[Borislav Petkov]

On Thu, Nov 28, 2019 at 07:56:07PM +0100, Dominik Brodowski wrote:
> Seems to work fine now. Thanks!

Does that mean I can add Reported-by: and Tested-by: you?

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette

Re: unchecked MSR access error in throttle_active_work()

[Dominik Brodowski]

On Thu, Nov 28, 2019 at 08:12:18PM +0100, Borislav Petkov wrote:
> On Thu, Nov 28, 2019 at 07:56:07PM +0100, Dominik Brodowski wrote:
> > Seems to work fine now. Thanks!
> 
> Does that mean I can add Reported-by: and Tested-by: you?

Srinivas Pandruvada already had added my Reported-by,[*] and you may extend
that by a Tested-by (or a combination thereof).

Thanks,
	Dominik

[*] https://lore.kernel.org/lkml/20191128150824.22413-1-srinivas.pandruvada@linux.intel.com/