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Subject[PATCH v2 3/4] arm64: smp: Setup IPI_CALL_NMI_FUNC as a pseudo NMI
Date
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.garg@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
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