[PATCH v2 3/4] arm64: smp: Setup IPI_CALL_NMI_FUNC as a pseudo NMI

[Sumit Garg]

Setup IPI_CALL_NMI_FUNC as a pseudo NMI using generic interrupt framework
APIs. In case a plarform doesn't provide support for pseudo NMIs, switch
back to IPI_CALL_NMI_FUNC being a normal interrupt.

Signed-off-by: Sumit Garg <sumit.g...@linaro.org>
---
 arch/arm64/kernel/smp.c | 35 ++++++++++++++++++++++++++---------
 1 file changed, 26 insertions(+), 9 deletions(-)

diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index 236784e..c5e42a1 100644
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c
@@ -68,6 +68,7 @@ struct secondary_data secondary_data;
 int cpus_stuck_in_kernel;
 
 static int ipi_irq_base;
+static int ipi_nmi = -1;
 static int nr_ipi = NR_IPI;
 static struct irq_desc *ipi_desc[NR_IPI];
 
@@ -986,8 +987,14 @@ static void ipi_setup(int cpu)
        if (ipi_irq_base) {
                int i;
 
-               for (i = 0; i < nr_ipi; i++)
-                       enable_percpu_irq(ipi_irq_base + i, 0);
+               for (i = 0; i < nr_ipi; i++) {
+                       if (ipi_nmi == ipi_irq_base + i) {
+                               if (!prepare_percpu_nmi(ipi_nmi))
+                                       enable_percpu_nmi(ipi_nmi, 0);
+                       } else {
+                               enable_percpu_irq(ipi_irq_base + i, 0);
+                       }
+               }
        }
 }
 
@@ -997,23 +1004,33 @@ static void ipi_teardown(int cpu)
                int i;
 
                for (i = 0; i < nr_ipi; i++)
-                       disable_percpu_irq(ipi_irq_base + i);
+                       if (ipi_nmi == ipi_irq_base + i) {
+                               disable_percpu_nmi(ipi_nmi);
+                               teardown_percpu_nmi(ipi_nmi);
+                       } else {
+                               disable_percpu_irq(ipi_irq_base + i);
+                       }
        }
 }
 
 void __init set_smp_ipi_range(int ipi_base, int n)
 {
-       int i;
+       int i, err;
 
        WARN_ON(n < NR_IPI);
        nr_ipi = min(n, NR_IPI);
 
-       for (i = 0; i < nr_ipi; i++) {
-               int err;
+       err = request_percpu_nmi(ipi_base + IPI_CALL_NMI_FUNC,
+                                ipi_handler, "IPI", &irq_stat);
+       if (!err)
+               ipi_nmi = ipi_base + IPI_CALL_NMI_FUNC;
 
-               err = request_percpu_irq(ipi_base + i, ipi_handler,
-                                        "IPI", &irq_stat);
-               WARN_ON(err);
+       for (i = 0; i < nr_ipi; i++) {
+               if (ipi_base + i != ipi_nmi) {
+                       err = request_percpu_irq(ipi_base + i, ipi_handler,
+                                                "IPI", &irq_stat);
+                       WARN_ON(err);
+               }
 
                ipi_desc[i] = irq_to_desc(ipi_base + i);
                irq_set_status_flags(ipi_base + i, IRQ_NO_ACCOUNTING);
-- 
2.7.4