linux-kernel - [PATCH v4 1/3] genirq: Add flags for software interrupt moderation.

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Message-ID: <20260115155942.482137-2-lrizzo@google.com>
Date: Thu, 15 Jan 2026 15:59:40 +0000
From: Luigi Rizzo <lrizzo@...gle.com>
To: Thomas Gleixner <tglx@...utronix.de>, Marc Zyngier <maz@...nel.org>, 
	Luigi Rizzo <rizzo.unipi@...il.com>, Paolo Abeni <pabeni@...hat.com>, 
	Andrew Morton <akpm@...ux-foundation.org>, Sean Christopherson <seanjc@...gle.com>, 
	Jacob Pan <jacob.jun.pan@...ux.intel.com>
Cc: linux-kernel@...r.kernel.org, linux-arch@...r.kernel.org, 
	Bjorn Helgaas <bhelgaas@...gle.com>, Willem de Bruijn <willemb@...gle.com>, 
	Luigi Rizzo <lrizzo@...gle.com>
Subject: [PATCH v4 1/3] genirq: Add flags for software interrupt moderation.

Add two flags to support software interrupt moderation:

- IRQ_SW_MODERATION is an irqdesc flag indicating that an interrupt supports
  moderation. This is a feature that can be set by the system
  administrator.
- IRQD_IRQ_MODERATED is an internal irqdata flag indicating that the
  interrupt is currently being moderated. This is a state flag.

Signed-off-by: Luigi Rizzo <lrizzo@...gle.com>
---
 include/linux/irq.h   | 6 +++++-
 kernel/irq/settings.h | 7 +++++++
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/include/linux/irq.h b/include/linux/irq.h
index 4a9f1d7b08c39..df653e10a83bf 100644
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -72,6 +72,7 @@ enum irqchip_irq_state;
  * IRQ_DISABLE_UNLAZY		- Disable lazy irq disable
  * IRQ_HIDDEN			- Don't show up in /proc/interrupts
  * IRQ_NO_DEBUG			- Exclude from note_interrupt() debugging
+ * IRQ_SW_MODERATION		- Can do software interrupt moderation
  */
 enum {
 	IRQ_TYPE_NONE		= 0x00000000,
@@ -99,13 +100,14 @@ enum {
 	IRQ_DISABLE_UNLAZY	= (1 << 19),
 	IRQ_HIDDEN		= (1 << 20),
 	IRQ_NO_DEBUG		= (1 << 21),
+	IRQ_SW_MODERATION	= (1 << 22),
 };
 
 #define IRQF_MODIFY_MASK	\
 	(IRQ_TYPE_SENSE_MASK | IRQ_NOPROBE | IRQ_NOREQUEST | \
 	 IRQ_NOAUTOEN | IRQ_LEVEL | IRQ_NO_BALANCING | \
 	 IRQ_PER_CPU | IRQ_NESTED_THREAD | IRQ_NOTHREAD | IRQ_PER_CPU_DEVID | \
-	 IRQ_IS_POLLED | IRQ_DISABLE_UNLAZY | IRQ_HIDDEN)
+	 IRQ_IS_POLLED | IRQ_DISABLE_UNLAZY | IRQ_HIDDEN | IRQ_SW_MODERATION)
 
 #define IRQ_NO_BALANCING_MASK	(IRQ_PER_CPU | IRQ_NO_BALANCING)
 
@@ -219,6 +221,7 @@ struct irq_data {
  *				  irqchip have flag IRQCHIP_ENABLE_WAKEUP_ON_SUSPEND set.
  * IRQD_RESEND_WHEN_IN_PROGRESS	- Interrupt may fire when already in progress in which
  *				  case it must be resent at the next available opportunity.
+ * IRQD_IRQ_MODERATED		- Interrupt is currently moderated.
  */
 enum {
 	IRQD_TRIGGER_MASK		= 0xf,
@@ -244,6 +247,7 @@ enum {
 	IRQD_AFFINITY_ON_ACTIVATE	= BIT(28),
 	IRQD_IRQ_ENABLED_ON_SUSPEND	= BIT(29),
 	IRQD_RESEND_WHEN_IN_PROGRESS    = BIT(30),
+	IRQD_IRQ_MODERATED		= BIT(31),
 };
 
 #define __irqd_to_state(d) ACCESS_PRIVATE((d)->common, state_use_accessors)
diff --git a/kernel/irq/settings.h b/kernel/irq/settings.h
index 00b3bd127692c..bc8ade4726322 100644
--- a/kernel/irq/settings.h
+++ b/kernel/irq/settings.h
@@ -18,6 +18,7 @@ enum {
 	_IRQ_DISABLE_UNLAZY	= IRQ_DISABLE_UNLAZY,
 	_IRQ_HIDDEN		= IRQ_HIDDEN,
 	_IRQ_NO_DEBUG		= IRQ_NO_DEBUG,
+	_IRQ_SW_MODERATION	= IRQ_SW_MODERATION,
 	_IRQF_MODIFY_MASK	= IRQF_MODIFY_MASK,
 };
 
@@ -34,6 +35,7 @@ enum {
 #define IRQ_DISABLE_UNLAZY	GOT_YOU_MORON
 #define IRQ_HIDDEN		GOT_YOU_MORON
 #define IRQ_NO_DEBUG		GOT_YOU_MORON
+#define IRQ_SW_MODERATION	GOT_YOU_MORON
 #undef IRQF_MODIFY_MASK
 #define IRQF_MODIFY_MASK	GOT_YOU_MORON
 
@@ -180,3 +182,8 @@ static inline bool irq_settings_no_debug(struct irq_desc *desc)
 {
 	return desc->status_use_accessors & _IRQ_NO_DEBUG;
 }
+
+static inline bool irq_settings_moderation_allowed(struct irq_desc *desc)
+{
+	return desc->status_use_accessors & _IRQ_SW_MODERATION;
+}
-- 
2.52.0.457.g6b5491de43-goog