linux-kernel - [PATCH v2 1/3] irqchip/gic-v3: Enable support for SGIs to act as NMIs

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Date:   Wed,  4 Nov 2020 17:05:37 +0900
From:   Yuichi Ito <ito-yuichi@...itsu.com>
To:     maz@...nel.org, sumit.garg@...aro.org, tglx@...utronix.de,
        jason@...edaemon.net, catalin.marinas@....com, will@...nel.org
Cc:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [PATCH v2 1/3] irqchip/gic-v3: Enable support for SGIs to act as NMIs

From: From: Sumit Garg <sumit.garg@...aro.org>

Add support to handle SGIs as pseudo NMIs. As SGIs or IPIs default to a
special flow handler: handle_percpu_devid_fasteoi_ipi(), so skip NMI
handler update in case of SGIs.

Also, enable NMI support prior to gic_smp_init() as allocation of SGIs
as IRQs/NMIs happen as part of this routine.

Signed-off-by: Sumit Garg <sumit.garg@...aro.org>
---
 drivers/irqchip/irq-gic-v3.c | 29 +++++++++++++++++++++--------
 1 file changed, 21 insertions(+), 8 deletions(-)

diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c
index 16fecc0..7010ae2 100644
--- a/drivers/irqchip/irq-gic-v3.c
+++ b/drivers/irqchip/irq-gic-v3.c
@@ -461,6 +461,7 @@ static u32 gic_get_ppi_index(struct irq_data *d)
 static int gic_irq_nmi_setup(struct irq_data *d)
 {
 	struct irq_desc *desc = irq_to_desc(d->irq);
+	u32 idx;
 
 	if (!gic_supports_nmi())
 		return -EINVAL;
@@ -478,16 +479,22 @@ static int gic_irq_nmi_setup(struct irq_data *d)
 		return -EINVAL;
 
 	/* desc lock should already be held */
-	if (gic_irq_in_rdist(d)) {
-		u32 idx = gic_get_ppi_index(d);
+	switch (get_intid_range(d)) {
+	case SGI_RANGE:
+		break;
+	case PPI_RANGE:
+	case EPPI_RANGE:
+		idx = gic_get_ppi_index(d);
 
 		/* Setting up PPI as NMI, only switch handler for first NMI */
 		if (!refcount_inc_not_zero(&ppi_nmi_refs[idx])) {
 			refcount_set(&ppi_nmi_refs[idx], 1);
 			desc->handle_irq = handle_percpu_devid_fasteoi_nmi;
 		}
-	} else {
+		break;
+	default:
 		desc->handle_irq = handle_fasteoi_nmi;
+		break;
 	}
 
 	gic_irq_set_prio(d, GICD_INT_NMI_PRI);
@@ -498,6 +505,7 @@ static int gic_irq_nmi_setup(struct irq_data *d)
 static void gic_irq_nmi_teardown(struct irq_data *d)
 {
 	struct irq_desc *desc = irq_to_desc(d->irq);
+	u32 idx;
 
 	if (WARN_ON(!gic_supports_nmi()))
 		return;
@@ -515,14 +523,20 @@ static void gic_irq_nmi_teardown(struct irq_data *d)
 		return;
 
 	/* desc lock should already be held */
-	if (gic_irq_in_rdist(d)) {
-		u32 idx = gic_get_ppi_index(d);
+	switch (get_intid_range(d)) {
+	case SGI_RANGE:
+		break;
+	case PPI_RANGE:
+	case EPPI_RANGE:
+		idx = gic_get_ppi_index(d);
 
 		/* Tearing down NMI, only switch handler for last NMI */
 		if (refcount_dec_and_test(&ppi_nmi_refs[idx]))
 			desc->handle_irq = handle_percpu_devid_irq;
-	} else {
+		break;
+	default:
 		desc->handle_irq = handle_fasteoi_irq;
+		break;
 	}
 
 	gic_irq_set_prio(d, GICD_INT_DEF_PRI);
@@ -1708,6 +1722,7 @@ static int __init gic_init_bases(void __iomem *dist_base,
 
 	gic_dist_init();
 	gic_cpu_init();
+	gic_enable_nmi_support();
 	gic_smp_init();
 	gic_cpu_pm_init();
 
@@ -1719,8 +1734,6 @@ static int __init gic_init_bases(void __iomem *dist_base,
 			gicv2m_init(handle, gic_data.domain);
 	}
 
-	gic_enable_nmi_support();
-
 	return 0;
 
 out_free:
-- 
1.8.3.1