x86: Cleanup NMI handling

[PATCH 1/9] x86/nmi: Simplify unknown NMI panic handling

Posted by Sohil Mehta 8 months, 3 weeks ago

The unknown_nmi_panic variable is used to control whether the kernel
should panic on unknown NMIs. There is a sysctl entry for the same, which
can be used to change the behavior at runtime.

However, it seems that in some places, the option unnecessarily depends
on CONFIG_X86_LOCAL_APIC. Other code in nmi.c uses unknown_nmi_panic
without such a dependency. This results in a few messy #ifdefs
splattered across the code. The dependency was likely introduce due to a
potential compile issue [1] reported a long time ago. Such an issue no
longer exists.

Also, similar NMI panic options, such as panic_on_unrecovered_nmi and
panic_on_io_nmi, do not have an explicit dependency on the local APIC.
Though, it's hard to imagine a production system without the local APIC
configuration, making a specific NMI sysctl option dependent on it
doesn't make sense.

Remove the explicit dependency between unknown NMI handling and the
local APIC to make the code cleaner and more consistent.

While at it, reorder the header includes to maintain alphabetical order.

[1]: https://lore.kernel.org/lkml/40BC67F9.3000609@myrealbox.com/

Signed-off-by: Sohil Mehta <sohil.mehta@intel.com>
---
 arch/x86/include/asm/nmi.h |  4 ++--
 arch/x86/kernel/setup.c    | 37 ++++++++++++++++---------------------
 2 files changed, 18 insertions(+), 23 deletions(-)

diff --git a/arch/x86/include/asm/nmi.h b/arch/x86/include/asm/nmi.h
index f677382093f3..9cf96cce02fc 100644
--- a/arch/x86/include/asm/nmi.h
+++ b/arch/x86/include/asm/nmi.h
@@ -14,10 +14,10 @@ extern void release_perfctr_nmi(unsigned int);
 extern int reserve_evntsel_nmi(unsigned int);
 extern void release_evntsel_nmi(unsigned int);
 
-extern int unknown_nmi_panic;
-
 #endif /* CONFIG_X86_LOCAL_APIC */
 
+extern int unknown_nmi_panic;
+
 #define NMI_FLAG_FIRST	1
 
 enum {
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index c7164a8de983..c3e1ae7373e9 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -7,10 +7,11 @@
  */
 #include <linux/acpi.h>
 #include <linux/console.h>
-#include <linux/cpu.h>
 #include <linux/crash_dump.h>
+#include <linux/cpu.h>
 #include <linux/dma-map-ops.h>
 #include <linux/efi.h>
+#include <linux/hugetlb.h>
 #include <linux/ima.h>
 #include <linux/init_ohci1394_dma.h>
 #include <linux/initrd.h>
@@ -18,21 +19,19 @@
 #include <linux/memblock.h>
 #include <linux/panic_notifier.h>
 #include <linux/pci.h>
+#include <linux/random.h>
 #include <linux/root_dev.h>
-#include <linux/hugetlb.h>
-#include <linux/tboot.h>
-#include <linux/usb/xhci-dbgp.h>
 #include <linux/static_call.h>
 #include <linux/swiotlb.h>
-#include <linux/random.h>
+#include <linux/tboot.h>
+#include <linux/usb/xhci-dbgp.h>
+#include <linux/vmalloc.h>
 
 #include <uapi/linux/mount.h>
 
 #include <xen/xen.h>
 
 #include <asm/apic.h>
-#include <asm/efi.h>
-#include <asm/numa.h>
 #include <asm/bios_ebda.h>
 #include <asm/bugs.h>
 #include <asm/cacheinfo.h>
@@ -47,18 +46,16 @@
 #include <asm/mce.h>
 #include <asm/memtype.h>
 #include <asm/mtrr.h>
-#include <asm/realmode.h>
+#include <asm/nmi.h>
+#include <asm/numa.h>
 #include <asm/olpc_ofw.h>
 #include <asm/pci-direct.h>
 #include <asm/prom.h>
 #include <asm/proto.h>
+#include <asm/realmode.h>
 #include <asm/thermal.h>
 #include <asm/unwind.h>
 #include <asm/vsyscall.h>
-#include <linux/vmalloc.h>
-#if defined(CONFIG_X86_LOCAL_APIC)
-#include <asm/nmi.h>
-#endif
 
 /*
  * max_low_pfn_mapped: highest directly mapped pfn < 4 GB
@@ -150,6 +147,13 @@ static size_t ima_kexec_buffer_size;
 int bootloader_type, bootloader_version;
 
 static const struct ctl_table x86_sysctl_table[] = {
+	{
+		.procname       = "unknown_nmi_panic",
+		.data           = &unknown_nmi_panic,
+		.maxlen         = sizeof(int),
+		.mode           = 0644,
+		.proc_handler   = proc_dointvec,
+	},
 	{
 		.procname	= "panic_on_unrecovered_nmi",
 		.data		= &panic_on_unrecovered_nmi,
@@ -185,15 +189,6 @@ static const struct ctl_table x86_sysctl_table[] = {
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec,
 	},
-#if defined(CONFIG_X86_LOCAL_APIC)
-	{
-		.procname       = "unknown_nmi_panic",
-		.data           = &unknown_nmi_panic,
-		.maxlen         = sizeof(int),
-		.mode           = 0644,
-		.proc_handler   = proc_dointvec,
-	},
-#endif
 #if defined(CONFIG_ACPI_SLEEP)
 	{
 		.procname	= "acpi_video_flags",
-- 
2.43.0

Re: [PATCH 1/9] x86/nmi: Simplify unknown NMI panic handling

Posted by Nikolay Borisov 8 months, 2 weeks ago


On 28.03.25 г. 1:46 ч., Sohil Mehta wrote:
> The unknown_nmi_panic variable is used to control whether the kernel
> should panic on unknown NMIs. There is a sysctl entry for the same, which
> can be used to change the behavior at runtime.
> 
> However, it seems that in some places, the option unnecessarily depends
> on CONFIG_X86_LOCAL_APIC. Other code in nmi.c uses unknown_nmi_panic
> without such a dependency. This results in a few messy #ifdefs
> splattered across the code. The dependency was likely introduce due to a
> potential compile issue [1] reported a long time ago. Such an issue no
> longer exists.
> 
> Also, similar NMI panic options, such as panic_on_unrecovered_nmi and
> panic_on_io_nmi, do not have an explicit dependency on the local APIC.
> Though, it's hard to imagine a production system without the local APIC
> configuration, making a specific NMI sysctl option dependent on it
> doesn't make sense.
> 
> Remove the explicit dependency between unknown NMI handling and the
> local APIC to make the code cleaner and more consistent.
> 
> While at it, reorder the header includes to maintain alphabetical order.
 > > [1]: https://lore.kernel.org/lkml/40BC67F9.3000609@myrealbox.com/
> 
> Signed-off-by: Sohil Mehta <sohil.mehta@intel.com>
> ---
>   arch/x86/include/asm/nmi.h |  4 ++--
>   arch/x86/kernel/setup.c    | 37 ++++++++++++++++---------------------
>   2 files changed, 18 insertions(+), 23 deletions(-)
> 
> diff --git a/arch/x86/include/asm/nmi.h b/arch/x86/include/asm/nmi.h
> index f677382093f3..9cf96cce02fc 100644
> --- a/arch/x86/include/asm/nmi.h
> +++ b/arch/x86/include/asm/nmi.h
> @@ -14,10 +14,10 @@ extern void release_perfctr_nmi(unsigned int);
>   extern int reserve_evntsel_nmi(unsigned int);
>   extern void release_evntsel_nmi(unsigned int);
>   
> -extern int unknown_nmi_panic;
> -
>   #endif /* CONFIG_X86_LOCAL_APIC */
>   
> +extern int unknown_nmi_panic;
> +
>   #define NMI_FLAG_FIRST	1
>   
>   enum {
> diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
> index c7164a8de983..c3e1ae7373e9 100644
> --- a/arch/x86/kernel/setup.c
> +++ b/arch/x86/kernel/setup.c
> @@ -7,10 +7,11 @@
>    */
>   #include <linux/acpi.h>
>   #include <linux/console.h>
> -#include <linux/cpu.h>
>   #include <linux/crash_dump.h>
> +#include <linux/cpu.h>
>   #include <linux/dma-map-ops.h>
>   #include <linux/efi.h>
> +#include <linux/hugetlb.h>
>   #include <linux/ima.h>
>   #include <linux/init_ohci1394_dma.h>
>   #include <linux/initrd.h>
> @@ -18,21 +19,19 @@
>   #include <linux/memblock.h>
>   #include <linux/panic_notifier.h>
>   #include <linux/pci.h>
> +#include <linux/random.h>
>   #include <linux/root_dev.h>
> -#include <linux/hugetlb.h>
> -#include <linux/tboot.h>
> -#include <linux/usb/xhci-dbgp.h>
>   #include <linux/static_call.h>
>   #include <linux/swiotlb.h>
> -#include <linux/random.h>
> +#include <linux/tboot.h>
> +#include <linux/usb/xhci-dbgp.h>
> +#include <linux/vmalloc.h>
>   
>   #include <uapi/linux/mount.h>
>   
>   #include <xen/xen.h>
>   
>   #include <asm/apic.h>
> -#include <asm/efi.h>
> -#include <asm/numa.h>
>   #include <asm/bios_ebda.h>
>   #include <asm/bugs.h>
>   #include <asm/cacheinfo.h>
> @@ -47,18 +46,16 @@
>   #include <asm/mce.h>
>   #include <asm/memtype.h>
>   #include <asm/mtrr.h>
> -#include <asm/realmode.h>
> +#include <asm/nmi.h>
> +#include <asm/numa.h>
>   #include <asm/olpc_ofw.h>
>   #include <asm/pci-direct.h>
>   #include <asm/prom.h>
>   #include <asm/proto.h>
> +#include <asm/realmode.h>
>   #include <asm/thermal.h>
>   #include <asm/unwind.h>
>   #include <asm/vsyscall.h>
> -#include <linux/vmalloc.h>
> -#if defined(CONFIG_X86_LOCAL_APIC)
> -#include <asm/nmi.h>
> -#endif

As far as headers are concerned only this change falls under the 
"simplify nmi handling code" the others while nice cleanups should 
ideally be in a separate patch.

>   
>   /*
>    * max_low_pfn_mapped: highest directly mapped pfn < 4 GB
> @@ -150,6 +147,13 @@ static size_t ima_kexec_buffer_size;
>   int bootloader_type, bootloader_version;
>   
>   static const struct ctl_table x86_sysctl_table[] = {
> +	{
> +		.procname       = "unknown_nmi_panic",
> +		.data           = &unknown_nmi_panic,
> +		.maxlen         = sizeof(int),
> +		.mode           = 0644,
> +		.proc_handler   = proc_dointvec,
> +	},
>   	{
>   		.procname	= "panic_on_unrecovered_nmi",
>   		.data		= &panic_on_unrecovered_nmi,
> @@ -185,15 +189,6 @@ static const struct ctl_table x86_sysctl_table[] = {
>   		.mode		= 0644,
>   		.proc_handler	= proc_dointvec,
>   	},
> -#if defined(CONFIG_X86_LOCAL_APIC)
> -	{
> -		.procname       = "unknown_nmi_panic",
> -		.data           = &unknown_nmi_panic,
> -		.maxlen         = sizeof(int),
> -		.mode           = 0644,
> -		.proc_handler   = proc_dointvec,
> -	},
> -#endif

Why move the definition and not just delete the #ifdef ?

>   #if defined(CONFIG_ACPI_SLEEP)
>   	{
>   		.procname	= "acpi_video_flags",

Re: [PATCH 1/9] x86/nmi: Simplify unknown NMI panic handling

Posted by Sohil Mehta 8 months, 2 weeks ago

On 4/1/2025 8:00 AM, Nikolay Borisov wrote:

>> +#include <asm/realmode.h>
>>   #include <asm/thermal.h>
>>   #include <asm/unwind.h>
>>   #include <asm/vsyscall.h>
>> -#include <linux/vmalloc.h>
>> -#if defined(CONFIG_X86_LOCAL_APIC)
>> -#include <asm/nmi.h>
>> -#endif
> 
> As far as headers are concerned only this change falls under the 
> "simplify nmi handling code" the others while nice cleanups should 
> ideally be in a separate patch.
> 

You are right. The simplification is only for the #ifdef. I could have
just removed the CONFIG check and left the rest of the headers as-is.

But the <linux/vmalloc.h> include there was completely out of place and
needed to be moved. This eventually led to the reshuffle.

I feel header reordering by itself may not be considered worthwhile as a
patch. Since this series is focussed on cleanups, I tried to keep
cleanups in the same vicinity together. It's mainly to avoid bloating
the patch count but still keep the reviewing of these changes manageable.

>>   
>>   /*
>>    * max_low_pfn_mapped: highest directly mapped pfn < 4 GB
>> @@ -150,6 +147,13 @@ static size_t ima_kexec_buffer_size;
>>   int bootloader_type, bootloader_version;
>>   
>>   static const struct ctl_table x86_sysctl_table[] = {
>> +	{
>> +		.procname       = "unknown_nmi_panic",
>> +		.data           = &unknown_nmi_panic,
>> +		.maxlen         = sizeof(int),
>> +		.mode           = 0644,
>> +		.proc_handler   = proc_dointvec,
>> +	},
>>   	{
>>   		.procname	= "panic_on_unrecovered_nmi",
>>   		.data		= &panic_on_unrecovered_nmi,
>> @@ -185,15 +189,6 @@ static const struct ctl_table x86_sysctl_table[] = {
>>   		.mode		= 0644,
>>   		.proc_handler	= proc_dointvec,
>>   	},
>> -#if defined(CONFIG_X86_LOCAL_APIC)
>> -	{
>> -		.procname       = "unknown_nmi_panic",
>> -		.data           = &unknown_nmi_panic,
>> -		.maxlen         = sizeof(int),
>> -		.mode           = 0644,
>> -		.proc_handler   = proc_dointvec,
>> -	},
>> -#endif
> 
> Why move the definition and not just delete the #ifdef ?
> 

Mainly for consistency. This keeps all the NMI panic options together in
x86_sysctl_table[].

>>   #if defined(CONFIG_ACPI_SLEEP)
>>   	{
>>   		.procname	= "acpi_video_flags",
>

Re: [PATCH 1/9] x86/nmi: Simplify unknown NMI panic handling

Posted by Huang, Kai 8 months, 2 weeks ago

On Thu, 2025-03-27 at 23:46 +0000, Mehta, Sohil wrote:
> The unknown_nmi_panic variable is used to control whether the kernel
> should panic on unknown NMIs. There is a sysctl entry for the same, which
> can be used to change the behavior at runtime.
> 
> However, it seems that in some places, the option unnecessarily depends
> on CONFIG_X86_LOCAL_APIC. Other code in nmi.c uses unknown_nmi_panic
> without such a dependency. This results in a few messy #ifdefs
> splattered across the code. The dependency was likely introduce due to a
							^
							introduced


[...]

> diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
> index c7164a8de983..c3e1ae7373e9 100644
> --- a/arch/x86/kernel/setup.c
> +++ b/arch/x86/kernel/setup.c
> @@ -7,10 +7,11 @@
>   */
>  #include <linux/acpi.h>
>  #include <linux/console.h>
> -#include <linux/cpu.h>
>  #include <linux/crash_dump.h>
> +#include <linux/cpu.h>

This code change doesn't seem to be able to make the headers in "alphabetical
order".

>  #include <linux/dma-map-ops.h>
>  #include <linux/efi.h>
> +#include <linux/hugetlb.h>
>  #include <linux/ima.h>
>  #include <linux/init_ohci1394_dma.h>
>  #include <linux/initrd.h>
> @@ -18,21 +19,19 @@
>  #include <linux/memblock.h>
>  #include <linux/panic_notifier.h>
>  #include <linux/pci.h>
> +#include <linux/random.h>
>  #include <linux/root_dev.h>
> -#include <linux/hugetlb.h>
> -#include <linux/tboot.h>
> -#include <linux/usb/xhci-dbgp.h>
>  #include <linux/static_call.h>
>  #include <linux/swiotlb.h>
> -#include <linux/random.h>
> +#include <linux/tboot.h>
> +#include <linux/usb/xhci-dbgp.h>
> +#include <linux/vmalloc.h>
>  
>  #include <uapi/linux/mount.h>
>  
>  #include <xen/xen.h>
>  
>  #include <asm/apic.h>
> -#include <asm/efi.h>

Seems this header just got removed here but was never added back.

> -#include <asm/numa.h>
>  #include <asm/bios_ebda.h>
>  #include <asm/bugs.h>
>  #include <asm/cacheinfo.h>
> @@ -47,18 +46,16 @@
>  #include <asm/mce.h>
>  #include <asm/memtype.h>
>  #include <asm/mtrr.h>
> -#include <asm/realmode.h>
> +#include <asm/nmi.h>
> +#include <asm/numa.h>
>  #include <asm/olpc_ofw.h>
>  #include <asm/pci-direct.h>
>  #include <asm/prom.h>
>  #include <asm/proto.h>
> +#include <asm/realmode.h>
>  #include <asm/thermal.h>
>  #include <asm/unwind.h>
>  #include <asm/vsyscall.h>
> -#include <linux/vmalloc.h>
> -#if defined(CONFIG_X86_LOCAL_APIC)
> -#include <asm/nmi.h>
> -#endif
>  

[...]

Re: [PATCH 1/9] x86/nmi: Simplify unknown NMI panic handling

Posted by Sohil Mehta 8 months, 2 weeks ago

On 3/31/2025 3:52 PM, Huang, Kai wrote:

>> diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
>> index c7164a8de983..c3e1ae7373e9 100644
>> --- a/arch/x86/kernel/setup.c
>> +++ b/arch/x86/kernel/setup.c
>> @@ -7,10 +7,11 @@
>>   */
>>  #include <linux/acpi.h>
>>  #include <linux/console.h>
>> -#include <linux/cpu.h>
>>  #include <linux/crash_dump.h>
>> +#include <linux/cpu.h>
> 
> This code change doesn't seem to be able to make the headers in "alphabetical
> order".
> 

Ah! Thanks for catching it.


>>  
>>  #include <asm/apic.h>
>> -#include <asm/efi.h>
> 
> Seems this header just got removed here but was never added back.
> 

<asm/efi.h> is included twice. Therefore, the diff only shows it being
removed.

>> -#include <asm/numa.h>
>>  #include <asm/bios_ebda.h>
>>  #include <asm/bugs.h>
>>  #include <asm/cacheinfo.h>

Thanks,
Sohil

[tip: x86/nmi] x86/nmi: Simplify unknown NMI panic handling

Posted by tip-bot2 for Sohil Mehta 8 months, 2 weeks ago

The following commit has been merged into the x86/nmi branch of tip:

Commit-ID:     2e016da1cbbd013368095270c040e065678c38f7
Gitweb:        https://git.kernel.org/tip/2e016da1cbbd013368095270c040e065678c38f7
Author:        Sohil Mehta <sohil.mehta@intel.com>
AuthorDate:    Thu, 27 Mar 2025 23:46:21 
Committer:     Ingo Molnar <mingo@kernel.org>
CommitterDate: Tue, 01 Apr 2025 22:25:41 +02:00

x86/nmi: Simplify unknown NMI panic handling

The unknown_nmi_panic variable is used to control whether the kernel
should panic on unknown NMIs. There is a sysctl entry under:

  /proc/sys/kernel/unknown_nmi_panic

which can be used to change the behavior at runtime.

However, it seems that in some places, the option unnecessarily depends
on CONFIG_X86_LOCAL_APIC. Other code in nmi.c uses unknown_nmi_panic
without such a dependency. This results in a few messy #ifdefs
splattered across the code. The dependency was likely introduce due to a
potential build bug reported a long time ago:

  https://lore.kernel.org/lkml/40BC67F9.3000609@myrealbox.com/

This build bug no longer exists.

Also, similar NMI panic options, such as panic_on_unrecovered_nmi and
panic_on_io_nmi, do not have an explicit dependency on the local APIC
either.

Though, it's hard to imagine a production system without the local APIC
configuration, making a specific NMI sysctl option dependent on it
doesn't make sense.

Remove the explicit dependency between unknown NMI handling and the
local APIC to make the code cleaner and more consistent.

While at it, reorder the header includes to maintain alphabetical order.

[ mingo: Cleaned up the changelog a bit, truly ordered the headers ... ]

Signed-off-by: Sohil Mehta <sohil.mehta@intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Nikolay Borisov <nik.borisov@suse.com>
Link: https://lore.kernel.org/r/20250327234629.3953536-2-sohil.mehta@intel.com
---
 arch/x86/include/asm/nmi.h |  4 ++--
 arch/x86/kernel/setup.c    | 35 +++++++++++++++--------------------
 2 files changed, 17 insertions(+), 22 deletions(-)

diff --git a/arch/x86/include/asm/nmi.h b/arch/x86/include/asm/nmi.h
index f677382..9cf96cc 100644
--- a/arch/x86/include/asm/nmi.h
+++ b/arch/x86/include/asm/nmi.h
@@ -14,10 +14,10 @@ extern void release_perfctr_nmi(unsigned int);
 extern int reserve_evntsel_nmi(unsigned int);
 extern void release_evntsel_nmi(unsigned int);
 
-extern int unknown_nmi_panic;
-
 #endif /* CONFIG_X86_LOCAL_APIC */
 
+extern int unknown_nmi_panic;
+
 #define NMI_FLAG_FIRST	1
 
 enum {
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index c7164a8..ecf4c13 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -11,6 +11,7 @@
 #include <linux/crash_dump.h>
 #include <linux/dma-map-ops.h>
 #include <linux/efi.h>
+#include <linux/hugetlb.h>
 #include <linux/ima.h>
 #include <linux/init_ohci1394_dma.h>
 #include <linux/initrd.h>
@@ -18,21 +19,19 @@
 #include <linux/memblock.h>
 #include <linux/panic_notifier.h>
 #include <linux/pci.h>
+#include <linux/random.h>
 #include <linux/root_dev.h>
-#include <linux/hugetlb.h>
-#include <linux/tboot.h>
-#include <linux/usb/xhci-dbgp.h>
 #include <linux/static_call.h>
 #include <linux/swiotlb.h>
-#include <linux/random.h>
+#include <linux/tboot.h>
+#include <linux/usb/xhci-dbgp.h>
+#include <linux/vmalloc.h>
 
 #include <uapi/linux/mount.h>
 
 #include <xen/xen.h>
 
 #include <asm/apic.h>
-#include <asm/efi.h>
-#include <asm/numa.h>
 #include <asm/bios_ebda.h>
 #include <asm/bugs.h>
 #include <asm/cacheinfo.h>
@@ -47,18 +46,16 @@
 #include <asm/mce.h>
 #include <asm/memtype.h>
 #include <asm/mtrr.h>
-#include <asm/realmode.h>
+#include <asm/nmi.h>
+#include <asm/numa.h>
 #include <asm/olpc_ofw.h>
 #include <asm/pci-direct.h>
 #include <asm/prom.h>
 #include <asm/proto.h>
+#include <asm/realmode.h>
 #include <asm/thermal.h>
 #include <asm/unwind.h>
 #include <asm/vsyscall.h>
-#include <linux/vmalloc.h>
-#if defined(CONFIG_X86_LOCAL_APIC)
-#include <asm/nmi.h>
-#endif
 
 /*
  * max_low_pfn_mapped: highest directly mapped pfn < 4 GB
@@ -151,6 +148,13 @@ int bootloader_type, bootloader_version;
 
 static const struct ctl_table x86_sysctl_table[] = {
 	{
+		.procname       = "unknown_nmi_panic",
+		.data           = &unknown_nmi_panic,
+		.maxlen         = sizeof(int),
+		.mode           = 0644,
+		.proc_handler   = proc_dointvec,
+	},
+	{
 		.procname	= "panic_on_unrecovered_nmi",
 		.data		= &panic_on_unrecovered_nmi,
 		.maxlen		= sizeof(int),
@@ -185,15 +189,6 @@ static const struct ctl_table x86_sysctl_table[] = {
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec,
 	},
-#if defined(CONFIG_X86_LOCAL_APIC)
-	{
-		.procname       = "unknown_nmi_panic",
-		.data           = &unknown_nmi_panic,
-		.maxlen         = sizeof(int),
-		.mode           = 0644,
-		.proc_handler   = proc_dointvec,
-	},
-#endif
 #if defined(CONFIG_ACPI_SLEEP)
 	{
 		.procname	= "acpi_video_flags",