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

[Sohil Mehta]

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@xxxxxxxxxxxxx/

Signed-off-by: Sohil Mehta <sohil.mehta@xxxxxxxxx>
---
 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