Commit 278c9b09 authored by travis@sgi.com's avatar travis@sgi.com Committed by Ingo Molnar
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x86/platform/UV: Add basic CPU NMI health check 



Add a low impact health check triggered by the system NMI command
that essentially checks which CPUs are responding to external NMI's.

Signed-off-by: default avatarMike Travis <travis@sgi.com>
Reviewed-by: default avatarRuss Anderson <rja@hpe.com>
Reviewed-by: default avatarAlex Thorlton <athorlton@sgi.com>
Acked-by: default avatarThomas Gleixner <tglx@linutronix.de>
Acked-by: default avatarDimitri Sivanich <sivanich@hpe.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20170125163517.756690240@asylum.americas.sgi.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent abdf1df6

arch/x86/platform/uv/uv_nmi.c

+20 −1
Original line number Diff line number Diff line
@@ -176,6 +176,7 @@ module_param_named(debug, uv_nmi_debug, int, 0644); 
 *  "kdump"	- do crash dump

 *  "kdb"	- enter KDB (default)

 *  "kgdb"	- enter KGDB

 *  "health"	- check if CPUs respond to NMI

 */

static char uv_nmi_action[8] = "kdb";

module_param_string(action, uv_nmi_action, sizeof(uv_nmi_action), 0644);
@@ -571,6 +572,22 @@ static void uv_nmi_sync_exit(int master) 
	}

}



/* Current "health" check is to check which CPU's are responsive */

static void uv_nmi_action_health(int cpu, struct pt_regs *regs, int master)

{

	if (master) {

		int in = atomic_read(&uv_nmi_cpus_in_nmi);

		int out = num_online_cpus() - in;



		pr_alert("UV: NMI CPU health check (non-responding:%d)\n", out);

		atomic_set(&uv_nmi_slave_continue, SLAVE_EXIT);

	} else {

		while (!atomic_read(&uv_nmi_slave_continue))

			cpu_relax();

	}

	uv_nmi_sync_exit(master);

}



/* Walk through cpu list and dump state of each */

static void uv_nmi_dump_state(int cpu, struct pt_regs *regs, int master)

{
@@ -747,7 +764,9 @@ int uv_handle_nmi(unsigned int reason, struct pt_regs *regs) 
	uv_nmi_wait(master);



	/* Process actions other than "kdump": */

	if (uv_nmi_action_is("ips") || uv_nmi_action_is("dump")) {

	if (uv_nmi_action_is("health")) {

		uv_nmi_action_health(cpu, regs, master);

	} else if (uv_nmi_action_is("ips") || uv_nmi_action_is("dump")) {

		uv_nmi_dump_state(cpu, regs, master);

	} else if (uv_nmi_action_is("kdb") || uv_nmi_action_is("kgdb")) {

		uv_call_kgdb_kdb(cpu, regs, master);

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