From a648eb3a3f79e9736a59b28783700c2c691db419 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Tue, 10 Dec 2024 11:34:14 +0100 Subject: [PATCH] genirq: Provide IRQCHIP_MOVE_DEFERRED The logic of GENERIC_PENDING_IRQ is backwards for historical reasons. Most interrupt controllers allow to move the interrupt from arbitrary contexts. If GENERIC_PENDING_IRQ is enabled by an architecture to support a chip, which requires the affinity change to happen in interrupt context, all other chips have to be marked with IRQF_MOVE_PCNTXT. That's tedious and there is no real good reason for the extra flags in the irq descriptor and the irq data status fields. In fact the decision whether interrupts can be moved in arbitrary context or not is a property of the interrupt chip. To simplify adoption for RISC-V provide a new mechanism which is enabled via a config switch and allows to add a flag to irq_chip::flags to request that interrupt affinity changes are deferred. Setting the top level chip of an interrupt evaluates the flag and maps it into the existing logic. The config switch and the various PCNTXT flags are temporary until x86 is converted over to this scheme. This intermediate step also allows trivial backporting of the mechanism to plug the affinity change race of various RISC-V interrupt controllers. Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/all/20241210103335.500314436@linutronix.de --- include/linux/irq.h | 2 ++ kernel/irq/Kconfig | 4 ++++ kernel/irq/chip.c | 18 +++++++++++++++--- kernel/irq/debugfs.c | 1 + 4 files changed, 22 insertions(+), 3 deletions(-) diff --git a/include/linux/irq.h b/include/linux/irq.h index 25f51bf3c351f..6e021548fa0a4 100644 --- a/include/linux/irq.h +++ b/include/linux/irq.h @@ -567,6 +567,7 @@ struct irq_chip { * in the suspend path if they are in disabled state * IRQCHIP_AFFINITY_PRE_STARTUP: Default affinity update before startup * IRQCHIP_IMMUTABLE: Don't ever change anything in this chip + * IRQCHIP_MOVE_DEFERRED: Move the interrupt in actual interrupt context */ enum { IRQCHIP_SET_TYPE_MASKED = (1 << 0), @@ -581,6 +582,7 @@ enum { IRQCHIP_ENABLE_WAKEUP_ON_SUSPEND = (1 << 9), IRQCHIP_AFFINITY_PRE_STARTUP = (1 << 10), IRQCHIP_IMMUTABLE = (1 << 11), + IRQCHIP_MOVE_DEFERRED = (1 << 12), }; #include diff --git a/kernel/irq/Kconfig b/kernel/irq/Kconfig index 875f25ed6f710..5432418c0feaf 100644 --- a/kernel/irq/Kconfig +++ b/kernel/irq/Kconfig @@ -31,6 +31,10 @@ config GENERIC_IRQ_EFFECTIVE_AFF_MASK config GENERIC_PENDING_IRQ bool +# Deduce delayed migration from top-level interrupt chip flags +config GENERIC_PENDING_IRQ_CHIPFLAGS + bool + # Support for generic irq migrating off cpu before the cpu is offline. config GENERIC_IRQ_MIGRATION bool diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c index 271e9139de77f..7989da287d4ca 100644 --- a/kernel/irq/chip.c +++ b/kernel/irq/chip.c @@ -47,6 +47,13 @@ int irq_set_chip(unsigned int irq, const struct irq_chip *chip) return -EINVAL; desc->irq_data.chip = (struct irq_chip *)(chip ?: &no_irq_chip); + + if (IS_ENABLED(CONFIG_GENERIC_PENDING_IRQ_CHIPFLAGS) && chip) { + if (chip->flags & IRQCHIP_MOVE_DEFERRED) + irqd_clear(&desc->irq_data, IRQD_MOVE_PCNTXT); + else + irqd_set(&desc->irq_data, IRQD_MOVE_PCNTXT); + } irq_put_desc_unlock(desc, flags); /* * For !CONFIG_SPARSE_IRQ make the irq show up in @@ -1114,16 +1121,21 @@ void irq_modify_status(unsigned int irq, unsigned long clr, unsigned long set) trigger = irqd_get_trigger_type(&desc->irq_data); irqd_clear(&desc->irq_data, IRQD_NO_BALANCING | IRQD_PER_CPU | - IRQD_TRIGGER_MASK | IRQD_LEVEL | IRQD_MOVE_PCNTXT); + IRQD_TRIGGER_MASK | IRQD_LEVEL); if (irq_settings_has_no_balance_set(desc)) irqd_set(&desc->irq_data, IRQD_NO_BALANCING); if (irq_settings_is_per_cpu(desc)) irqd_set(&desc->irq_data, IRQD_PER_CPU); - if (irq_settings_can_move_pcntxt(desc)) - irqd_set(&desc->irq_data, IRQD_MOVE_PCNTXT); if (irq_settings_is_level(desc)) irqd_set(&desc->irq_data, IRQD_LEVEL); + /* Keep this around until x86 is converted over */ + if (!IS_ENABLED(CONFIG_GENERIC_PENDING_IRQ_CHIPFLAGS)) { + irqd_clear(&desc->irq_data, IRQD_MOVE_PCNTXT); + if (irq_settings_can_move_pcntxt(desc)) + irqd_set(&desc->irq_data, IRQD_MOVE_PCNTXT); + } + tmp = irq_settings_get_trigger_mask(desc); if (tmp != IRQ_TYPE_NONE) trigger = tmp; diff --git a/kernel/irq/debugfs.c b/kernel/irq/debugfs.c index c6ffb97966bed..975eb8d681682 100644 --- a/kernel/irq/debugfs.c +++ b/kernel/irq/debugfs.c @@ -53,6 +53,7 @@ static const struct irq_bit_descr irqchip_flags[] = { BIT_MASK_DESCR(IRQCHIP_SUPPORTS_NMI), BIT_MASK_DESCR(IRQCHIP_ENABLE_WAKEUP_ON_SUSPEND), BIT_MASK_DESCR(IRQCHIP_IMMUTABLE), + BIT_MASK_DESCR(IRQCHIP_MOVE_DEFERRED), }; static void -- 2.47.2