linux-kernel - [tip: irq/core] irqchip/gic-v3: Switch high priority PPIs over to handle_percpu_devid

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Message-ID: <176158267154.2601451.17024825684483443214.tip-bot2@tip-bot2>
Date: Mon, 27 Oct 2025 16:31:11 -0000
From: "tip-bot2 for Marc Zyngier" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Will Deacon <will@...nel.org>, Marc Zyngier <maz@...nel.org>,
 Thomas Gleixner <tglx@...utronix.de>, x86@...nel.org,
 linux-kernel@...r.kernel.org
Subject: [tip: irq/core] irqchip/gic-v3: Switch high priority PPIs over to
 handle_percpu_devid_irq()

The following commit has been merged into the irq/core branch of tip:

Commit-ID:     21bbbc50f398f5d58a14669ee18b10a2bd30e916
Gitweb:        https://git.kernel.org/tip/21bbbc50f398f5d58a14669ee18b10a2bd30e916
Author:        Marc Zyngier <maz@...nel.org>
AuthorDate:    Mon, 20 Oct 2025 13:29:27 +01:00
Committer:     Thomas Gleixner <tglx@...utronix.de>
CommitterDate: Mon, 27 Oct 2025 17:16:34 +01:00

irqchip/gic-v3: Switch high priority PPIs over to handle_percpu_devid_irq()

It so appears that handle_percpu_devid_irq() is extremely similar to
handle_percpu_devid_fasteoi_nmi(), and that the differences do no justify
the horrid machinery in the GICv3 driver to handle the flow handler switch.

Stick with the standard flow handler, even for NMIs.

Suggested-by: Will Deacon <will@...nel.org>
Signed-off-by: Marc Zyngier <maz@...nel.org>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Tested-by: Will Deacon <will@...nel.org>
Link: https://patch.msgid.link/20251020122944.3074811-11-maz@kernel.org
---
 drivers/irqchip/irq-gic-v3.c | 54 +----------------------------------
 1 file changed, 2 insertions(+), 52 deletions(-)

diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c
index cf0ba83..dd2d6d7 100644
--- a/drivers/irqchip/irq-gic-v3.c
+++ b/drivers/irqchip/irq-gic-v3.c
@@ -230,9 +230,6 @@ static void __init gic_prio_init(void)
 		!cpus_have_group0);
 }
 
-/* rdist_nmi_refs[n] == number of cpus having the rdist interrupt n set as NMI */
-static refcount_t *rdist_nmi_refs;
-
 static struct gic_kvm_info gic_v3_kvm_info __initdata;
 static DEFINE_PER_CPU(bool, has_rss);
 
@@ -608,24 +605,6 @@ static u32 __gic_get_ppi_index(irq_hw_number_t hwirq)
 	}
 }
 
-static u32 __gic_get_rdist_index(irq_hw_number_t hwirq)
-{
-	switch (__get_intid_range(hwirq)) {
-	case SGI_RANGE:
-	case PPI_RANGE:
-		return hwirq;
-	case EPPI_RANGE:
-		return hwirq - EPPI_BASE_INTID + 32;
-	default:
-		unreachable();
-	}
-}
-
-static u32 gic_get_rdist_index(struct irq_data *d)
-{
-	return __gic_get_rdist_index(d->hwirq);
-}
-
 static int gic_irq_nmi_setup(struct irq_data *d)
 {
 	struct irq_desc *desc = irq_to_desc(d->irq);
@@ -646,20 +625,8 @@ 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_rdist_index(d);
-
-		/*
-		 * Setting up a percpu interrupt as NMI, only switch handler
-		 * for first NMI
-		 */
-		if (!refcount_inc_not_zero(&rdist_nmi_refs[idx])) {
-			refcount_set(&rdist_nmi_refs[idx], 1);
-			desc->handle_irq = handle_percpu_devid_fasteoi_nmi;
-		}
-	} else {
+	if (!gic_irq_in_rdist(d))
 		desc->handle_irq = handle_fasteoi_nmi;
-	}
 
 	gic_irq_set_prio(d, dist_prio_nmi);
 
@@ -686,15 +653,8 @@ 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_rdist_index(d);
-
-		/* Tearing down NMI, only switch handler for last NMI */
-		if (refcount_dec_and_test(&rdist_nmi_refs[idx]))
-			desc->handle_irq = handle_percpu_devid_irq;
-	} else {
+	if (!gic_irq_in_rdist(d))
 		desc->handle_irq = handle_fasteoi_irq;
-	}
 
 	gic_irq_set_prio(d, dist_prio_irq);
 }
@@ -2080,19 +2040,9 @@ static const struct gic_quirk gic_quirks[] = {
 
 static void gic_enable_nmi_support(void)
 {
-	int i;
-
 	if (!gic_prio_masking_enabled() || nmi_support_forbidden)
 		return;
 
-	rdist_nmi_refs = kcalloc(gic_data.ppi_nr + SGI_NR,
-				 sizeof(*rdist_nmi_refs), GFP_KERNEL);
-	if (!rdist_nmi_refs)
-		return;
-
-	for (i = 0; i < gic_data.ppi_nr + SGI_NR; i++)
-		refcount_set(&rdist_nmi_refs[i], 0);
-
 	pr_info("Pseudo-NMIs enabled using %s ICC_PMR_EL1 synchronisation\n",
 		gic_has_relaxed_pmr_sync() ? "relaxed" : "forced");