x86/UV: Move NMI support

This patch moves the UV NMI support from the x2apic file to a
new separate uv_nmi.c file in preparation for the next sequence
of patches. It prevents upcoming bloat of the x2apic file, and
has the added benefit of putting the upcoming /sys/module
parameters under the name 'uv_nmi' instead of 'x2apic_uv_x',
which was obscure.

Signed-off-by: Mike Travis <travis@sgi.com>
Reviewed-by: Dimitri Sivanich <sivanich@sgi.com>
Reviewed-by: Hedi Berriche <hedi@sgi.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Cc: Jason Wessel <jason.wessel@windriver.com>
Link: http://lkml.kernel.org/r/20130923212500.183295611@asylum.americas.sgi.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 102 insertions, 0 deletions

diff --git a/arch/x86/platform/uv/uv_nmi.c b/arch/x86/platform/uv/uv_nmi.c
new file mode 100644
index 000000000000..37feb60618b1
--- /dev/null
+++ b/arch/x86/platform/uv/uv_nmi.c
@@ -0,0 +1,102 @@
+/*
+ * SGI NMI support routines
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, write to the Free Software
+ *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
+ *
+ *  Copyright (c) 2009-2013 Silicon Graphics, Inc.  All Rights Reserved.
+ *  Copyright (c) Mike Travis
+ */
+
+#include <linux/cpu.h>
+#include <linux/nmi.h>
+
+#include <asm/apic.h>
+#include <asm/nmi.h>
+#include <asm/uv/uv.h>
+#include <asm/uv/uv_hub.h>
+#include <asm/uv/uv_mmrs.h>
+
+/* BMC sets a bit this MMR non-zero before sending an NMI */
+#define UVH_NMI_MMR				UVH_SCRATCH5
+#define UVH_NMI_MMR_CLEAR			(UVH_NMI_MMR + 8)
+#define UV_NMI_PENDING_MASK			(1UL << 63)
+DEFINE_PER_CPU(unsigned long, cpu_last_nmi_count);
+static DEFINE_SPINLOCK(uv_nmi_lock);
+
+/*
+ * When NMI is received, print a stack trace.
+ */
+int uv_handle_nmi(unsigned int reason, struct pt_regs *regs)
+{
+	unsigned long real_uv_nmi;
+	int bid;
+
+	/*
+	 * Each blade has an MMR that indicates when an NMI has been sent
+	 * to cpus on the blade. If an NMI is detected, atomically
+	 * clear the MMR and update a per-blade NMI count used to
+	 * cause each cpu on the blade to notice a new NMI.
+	 */
+	bid = uv_numa_blade_id();
+	real_uv_nmi = (uv_read_local_mmr(UVH_NMI_MMR) & UV_NMI_PENDING_MASK);
+
+	if (unlikely(real_uv_nmi)) {
+		spin_lock(&uv_blade_info[bid].nmi_lock);
+		real_uv_nmi = (uv_read_local_mmr(UVH_NMI_MMR) &
+				UV_NMI_PENDING_MASK);
+		if (real_uv_nmi) {
+			uv_blade_info[bid].nmi_count++;
+			uv_write_local_mmr(UVH_NMI_MMR_CLEAR,
+						UV_NMI_PENDING_MASK);
+		}
+		spin_unlock(&uv_blade_info[bid].nmi_lock);
+	}
+
+	if (likely(__get_cpu_var(cpu_last_nmi_count) ==
+			uv_blade_info[bid].nmi_count))
+		return NMI_DONE;
+
+	__get_cpu_var(cpu_last_nmi_count) = uv_blade_info[bid].nmi_count;
+
+	/*
+	 * Use a lock so only one cpu prints at a time.
+	 * This prevents intermixed output.
+	 */
+	spin_lock(&uv_nmi_lock);
+	pr_info("UV NMI stack dump cpu %u:\n", smp_processor_id());
+	dump_stack();
+	spin_unlock(&uv_nmi_lock);
+
+	return NMI_HANDLED;
+}
+
+void uv_register_nmi_notifier(void)
+{
+	if (register_nmi_handler(NMI_UNKNOWN, uv_handle_nmi, 0, "uv"))
+		pr_warn("UV NMI handler failed to register\n");
+}
+
+void uv_nmi_init(void)
+{
+	unsigned int value;
+
+	/*
+	 * Unmask NMI on all cpus
+	 */
+	value = apic_read(APIC_LVT1) | APIC_DM_NMI;
+	value &= ~APIC_LVT_MASKED;
+	apic_write(APIC_LVT1, value);
+}
+