linux-kernel - [PATCH 6/9] irqchip/gic-v3: Dynamically allocate PPI NMI refcounts

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Message-Id: <20190723104437.154403-7-maz@kernel.org>
Date:   Tue, 23 Jul 2019 11:44:34 +0100
From:   Marc Zyngier <maz@...nel.org>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Jason Cooper <jason@...edaemon.net>,
        Julien Thierry <julien.thierry.kdev@...il.com>,
        Rob Herring <robh+dt@...nel.org>
Cc:     linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: [PATCH 6/9] irqchip/gic-v3: Dynamically allocate PPI NMI refcounts

As we're about to have a variable number of PPIs, let's make the
allocation of the NMI refcounts dynamic. Also apply some minor
cleanups (moving things around).

Signed-off-by: Marc Zyngier <maz@...nel.org>
---
 drivers/irqchip/irq-gic-v3.c | 47 ++++++++++++++++++++++++++----------
 1 file changed, 34 insertions(+), 13 deletions(-)

diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c
index 2d4ecf36d0fd..ec0f885fa373 100644
--- a/drivers/irqchip/irq-gic-v3.c
+++ b/drivers/irqchip/irq-gic-v3.c
@@ -88,7 +88,7 @@ static DEFINE_STATIC_KEY_TRUE(supports_deactivate_key);
 static DEFINE_STATIC_KEY_FALSE(supports_pseudo_nmis);
 
 /* ppi_nmi_refs[n] == number of cpus having ppi[n + 16] set as NMI */
-static refcount_t ppi_nmi_refs[16];
+static refcount_t *ppi_nmi_refs;
 
 static struct gic_kvm_info gic_v3_kvm_info;
 static DEFINE_PER_CPU(bool, has_rss);
@@ -409,6 +409,16 @@ static void gic_irq_set_prio(struct irq_data *d, u8 prio)
 	writeb_relaxed(prio, base + offset + index);
 }
 
+static u32 gic_get_ppi_index(struct irq_data *d)
+{
+	switch (get_intid_range(d)) {
+	case PPI_RANGE:
+		return d->hwirq - 16;
+	default:
+		unreachable();
+	}
+}
+
 static int gic_irq_nmi_setup(struct irq_data *d)
 {
 	struct irq_desc *desc = irq_to_desc(d->irq);
@@ -429,10 +439,12 @@ static int gic_irq_nmi_setup(struct irq_data *d)
 		return -EINVAL;
 
 	/* desc lock should already be held */
-	if (gic_irq(d) < 32) {
+	if (gic_irq_in_rdist(d)) {
+		u32 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[gic_irq(d) - 16])) {
-			refcount_set(&ppi_nmi_refs[gic_irq(d) - 16], 1);
+		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 {
@@ -464,9 +476,11 @@ static void gic_irq_nmi_teardown(struct irq_data *d)
 		return;
 
 	/* desc lock should already be held */
-	if (gic_irq(d) < 32) {
+	if (gic_irq_in_rdist(d)) {
+		u32 idx = gic_get_ppi_index(d);
+
 		/* Tearing down NMI, only switch handler for last NMI */
-		if (refcount_dec_and_test(&ppi_nmi_refs[gic_irq(d) - 16]))
+		if (refcount_dec_and_test(&ppi_nmi_refs[idx]))
 			desc->handle_irq = handle_percpu_devid_irq;
 	} else {
 		desc->handle_irq = handle_fasteoi_irq;
@@ -1390,7 +1404,19 @@ static void gic_enable_nmi_support(void)
 {
 	int i;
 
-	for (i = 0; i < 16; i++)
+	if (!gic_prio_masking_enabled())
+		return;
+
+	if (gic_has_group0() && !gic_dist_security_disabled()) {
+		pr_warn("SCR_EL3.FIQ is cleared, cannot enable use of pseudo-NMIs\n");
+		return;
+	}
+
+	ppi_nmi_refs = kcalloc(gic_data.ppi_nr, sizeof(*ppi_nmi_refs), GFP_KERNEL);
+	if (!ppi_nmi_refs)
+		return;
+
+	for (i = 0; i < gic_data.ppi_nr; i++)
 		refcount_set(&ppi_nmi_refs[i], 0);
 
 	static_branch_enable(&supports_pseudo_nmis);
@@ -1468,12 +1494,7 @@ static int __init gic_init_bases(void __iomem *dist_base,
 			gicv2m_init(handle, gic_data.domain);
 	}
 
-	if (gic_prio_masking_enabled()) {
-		if (!gic_has_group0() || gic_dist_security_disabled())
-			gic_enable_nmi_support();
-		else
-			pr_warn("SCR_EL3.FIQ is cleared, cannot enable use of pseudo-NMIs\n");
-	}
+	gic_enable_nmi_support();
 
 	return 0;
 
-- 
2.20.1