From: Valentin Schneider <valentin.schneider@arm.com> To: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Cc: Marc Zyngier <maz@kernel.org>, Thomas Gleixner <tglx@linutronix.de>, Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>, Vincenzo Frascino <vincenzo.frascino@arm.com> Subject: [RFC PATCH v2 04/10] genirq: Add handle_strict_flow_irq() flow handler Date: Tue, 25 May 2021 18:32:49 +0100 [thread overview] Message-ID: <20210525173255.620606-5-valentin.schneider@arm.com> (raw) In-Reply-To: <20210525173255.620606-1-valentin.schneider@arm.com> The GIC family of irqchips have been so far treated as "fasteoi" chips. As handle_fasteoi_irq() states, this implies: * Only a single callback will be issued to the chip: an ->eoi() * call when the interrupt has been serviced. However, the GICs have an operating mode (EOImode=1) which requires an additional chip interaction during the IRQ handling. Said operating mode already has some uses with virtualization, but could also be leveraged to slightly optimize ONESHOT IRQs. This extra interaction is currently hidden away in the drivers, but further exploiting its effects (see IRQD_IRQ_FLOW_MASKED) requires lifting it from the driver code into core code. It so happens that it fits the role of ->irq_ack(); unfortunately, the GICs require both callbacks to be strictly paired with one another: for a given IRQ activation, there must be a single ->irq_ack() followed by a single ->irq_eoi(). No more, no less, and in that order. Introduce a new flow handler which guarantees said ack / eoi pairing. Note that it is strikingly similar to handle_fasteoi_mask_irq() for now, but will be further modified in later patches Signed-off-by: Valentin Schneider <valentin.schneider@arm.com> --- include/linux/irq.h | 1 + kernel/irq/chip.c | 48 +++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 49 insertions(+) diff --git a/include/linux/irq.h b/include/linux/irq.h index ef179245a642..37075929e329 100644 --- a/include/linux/irq.h +++ b/include/linux/irq.h @@ -663,6 +663,7 @@ extern void handle_edge_irq(struct irq_desc *desc); extern void handle_edge_eoi_irq(struct irq_desc *desc); extern void handle_simple_irq(struct irq_desc *desc); extern void handle_untracked_irq(struct irq_desc *desc); +extern void handle_strict_flow_irq(struct irq_desc *desc); extern void handle_percpu_irq(struct irq_desc *desc); extern void handle_percpu_devid_irq(struct irq_desc *desc); extern void handle_bad_irq(struct irq_desc *desc); diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c index 4d3bde55c5d9..699e70b51aae 100644 --- a/kernel/irq/chip.c +++ b/kernel/irq/chip.c @@ -896,6 +896,54 @@ void handle_edge_eoi_irq(struct irq_desc *desc) } #endif +/** + * handle_strict_flow_irq - irq handler for strict controllers + * @desc: the interrupt description structure for this irq + * + * Ensures strict pairing of ->ack() and ->eoi() for any IRQ passing + * through here. The ->eoi() may be deferred to the tail of the IRQ thread + * for ONESHOT IRQs. + */ +void handle_strict_flow_irq(struct irq_desc *desc) +{ + struct irq_chip *chip = desc->irq_data.chip; + + raw_spin_lock(&desc->lock); + mask_ack_irq(desc); + + if (!irq_may_run(desc)) + goto out; + + desc->istate &= ~(IRQS_REPLAY | IRQS_WAITING); + + /* + * If it's disabled or no action available then keep it masked and + * get out of here: + */ + if (unlikely(!desc->action || irqd_irq_disabled(&desc->irq_data))) { + desc->istate |= IRQS_PENDING; + goto out; + } + + kstat_incr_irqs_this_cpu(desc); + + handle_irq_event(desc); + + cond_unmask_eoi_irq(desc, chip); + + raw_spin_unlock(&desc->lock); + return; +out: + /* + * XXX: this is where IRQCHIP_EOI_IF_HANDLED would be checked, but + * it's conceptually incompatible with this handler (it breaks the + * strict pairing) + */ + eoi_irq(desc); + raw_spin_unlock(&desc->lock); +} +EXPORT_SYMBOL_GPL(handle_strict_flow_irq); + /** * handle_percpu_irq - Per CPU local irq handler * @desc: the interrupt description structure for this irq -- 2.25.1
WARNING: multiple messages have this Message-ID (diff)
From: Valentin Schneider <valentin.schneider@arm.com> To: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Cc: Marc Zyngier <maz@kernel.org>, Thomas Gleixner <tglx@linutronix.de>, Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>, Vincenzo Frascino <vincenzo.frascino@arm.com> Subject: [RFC PATCH v2 04/10] genirq: Add handle_strict_flow_irq() flow handler Date: Tue, 25 May 2021 18:32:49 +0100 [thread overview] Message-ID: <20210525173255.620606-5-valentin.schneider@arm.com> (raw) In-Reply-To: <20210525173255.620606-1-valentin.schneider@arm.com> The GIC family of irqchips have been so far treated as "fasteoi" chips. As handle_fasteoi_irq() states, this implies: * Only a single callback will be issued to the chip: an ->eoi() * call when the interrupt has been serviced. However, the GICs have an operating mode (EOImode=1) which requires an additional chip interaction during the IRQ handling. Said operating mode already has some uses with virtualization, but could also be leveraged to slightly optimize ONESHOT IRQs. This extra interaction is currently hidden away in the drivers, but further exploiting its effects (see IRQD_IRQ_FLOW_MASKED) requires lifting it from the driver code into core code. It so happens that it fits the role of ->irq_ack(); unfortunately, the GICs require both callbacks to be strictly paired with one another: for a given IRQ activation, there must be a single ->irq_ack() followed by a single ->irq_eoi(). No more, no less, and in that order. Introduce a new flow handler which guarantees said ack / eoi pairing. Note that it is strikingly similar to handle_fasteoi_mask_irq() for now, but will be further modified in later patches Signed-off-by: Valentin Schneider <valentin.schneider@arm.com> --- include/linux/irq.h | 1 + kernel/irq/chip.c | 48 +++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 49 insertions(+) diff --git a/include/linux/irq.h b/include/linux/irq.h index ef179245a642..37075929e329 100644 --- a/include/linux/irq.h +++ b/include/linux/irq.h @@ -663,6 +663,7 @@ extern void handle_edge_irq(struct irq_desc *desc); extern void handle_edge_eoi_irq(struct irq_desc *desc); extern void handle_simple_irq(struct irq_desc *desc); extern void handle_untracked_irq(struct irq_desc *desc); +extern void handle_strict_flow_irq(struct irq_desc *desc); extern void handle_percpu_irq(struct irq_desc *desc); extern void handle_percpu_devid_irq(struct irq_desc *desc); extern void handle_bad_irq(struct irq_desc *desc); diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c index 4d3bde55c5d9..699e70b51aae 100644 --- a/kernel/irq/chip.c +++ b/kernel/irq/chip.c @@ -896,6 +896,54 @@ void handle_edge_eoi_irq(struct irq_desc *desc) } #endif +/** + * handle_strict_flow_irq - irq handler for strict controllers + * @desc: the interrupt description structure for this irq + * + * Ensures strict pairing of ->ack() and ->eoi() for any IRQ passing + * through here. The ->eoi() may be deferred to the tail of the IRQ thread + * for ONESHOT IRQs. + */ +void handle_strict_flow_irq(struct irq_desc *desc) +{ + struct irq_chip *chip = desc->irq_data.chip; + + raw_spin_lock(&desc->lock); + mask_ack_irq(desc); + + if (!irq_may_run(desc)) + goto out; + + desc->istate &= ~(IRQS_REPLAY | IRQS_WAITING); + + /* + * If it's disabled or no action available then keep it masked and + * get out of here: + */ + if (unlikely(!desc->action || irqd_irq_disabled(&desc->irq_data))) { + desc->istate |= IRQS_PENDING; + goto out; + } + + kstat_incr_irqs_this_cpu(desc); + + handle_irq_event(desc); + + cond_unmask_eoi_irq(desc, chip); + + raw_spin_unlock(&desc->lock); + return; +out: + /* + * XXX: this is where IRQCHIP_EOI_IF_HANDLED would be checked, but + * it's conceptually incompatible with this handler (it breaks the + * strict pairing) + */ + eoi_irq(desc); + raw_spin_unlock(&desc->lock); +} +EXPORT_SYMBOL_GPL(handle_strict_flow_irq); + /** * handle_percpu_irq - Per CPU local irq handler * @desc: the interrupt description structure for this irq -- 2.25.1 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2021-05-25 17:33 UTC|newest] Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-05-25 17:32 [RFC PATCH v2 00/10] irqchip/irq-gic: Optimize masking by leveraging EOImode=1 Valentin Schneider 2021-05-25 17:32 ` Valentin Schneider 2021-05-25 17:32 ` [RFC PATCH v2 01/10] genirq: Add chip flag to denote automatic IRQ (un)masking Valentin Schneider 2021-05-25 17:32 ` Valentin Schneider 2021-05-25 17:32 ` [RFC PATCH v2 02/10] genirq: Define irq_ack() and irq_eoi() helpers Valentin Schneider 2021-05-25 17:32 ` Valentin Schneider 2021-05-25 20:54 ` kernel test robot 2021-05-27 10:55 ` Marc Zyngier 2021-05-27 10:55 ` Marc Zyngier 2021-05-27 10:58 ` Marc Zyngier 2021-05-27 10:58 ` Marc Zyngier 2021-06-01 10:25 ` Valentin Schneider 2021-06-01 10:25 ` Valentin Schneider 2021-05-25 17:32 ` [RFC PATCH v2 03/10] genirq: Employ ack_irq() and eoi_irq() where relevant Valentin Schneider 2021-05-25 17:32 ` Valentin Schneider 2021-05-25 17:32 ` Valentin Schneider [this message] 2021-05-25 17:32 ` [RFC PATCH v2 04/10] genirq: Add handle_strict_flow_irq() flow handler Valentin Schneider 2021-05-25 17:32 ` [RFC PATCH v2 05/10] genirq: Let purely flow-masked ONESHOT irqs through unmask_threaded_irq() Valentin Schneider 2021-05-25 17:32 ` Valentin Schneider 2021-05-25 17:32 ` [RFC PATCH v2 06/10] genirq: Don't mask IRQ within flow handler if IRQ is flow-masked Valentin Schneider 2021-05-25 17:32 ` Valentin Schneider 2021-05-25 17:32 ` [RFC PATCH v2 07/10] genirq, irq-gic-v3: Make NMI flow handlers use ->irq_ack() if available Valentin Schneider 2021-05-25 17:32 ` Valentin Schneider 2021-05-25 17:32 ` [RFC PATCH v2 08/10] irqchip/gic-v3-its: Use irq_chip_ack_parent() Valentin Schneider 2021-05-25 17:32 ` Valentin Schneider 2021-05-27 12:17 ` Marc Zyngier 2021-05-27 12:17 ` Marc Zyngier 2021-06-01 10:25 ` Valentin Schneider 2021-06-01 10:25 ` Valentin Schneider 2021-05-25 17:32 ` [RFC PATCH v2 09/10] irqchip/gic: Convert to handle_strict_flow_irq() Valentin Schneider 2021-05-25 17:32 ` Valentin Schneider 2021-05-27 12:21 ` Marc Zyngier 2021-05-27 12:21 ` Marc Zyngier 2021-06-01 10:25 ` Valentin Schneider 2021-06-01 10:25 ` Valentin Schneider 2021-06-15 15:20 ` Valentin Schneider 2021-06-15 15:20 ` Valentin Schneider 2021-05-25 17:32 ` [RFC PATCH v2 10/10] irqchip/gic-v3: " Valentin Schneider 2021-05-25 17:32 ` Valentin Schneider 2021-05-25 17:34 ` [RFC PATCH v2 00/10] irqchip/irq-gic: Optimize masking by leveraging EOImode=1 Valentin Schneider 2021-05-25 17:34 ` Valentin Schneider 2021-05-27 11:17 ` Marc Zyngier 2021-05-27 11:17 ` Marc Zyngier 2021-06-01 10:25 ` Valentin Schneider 2021-06-01 10:25 ` Valentin Schneider 2021-06-03 15:32 ` Valentin Schneider 2021-06-03 15:32 ` Valentin Schneider 2021-06-08 15:29 ` Marc Zyngier 2021-06-08 15:29 ` Marc Zyngier 2021-06-08 17:58 ` Lorenzo Pieralisi 2021-06-08 17:58 ` Lorenzo Pieralisi
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