| Message ID | 20200519161755.209565-2-maz@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | arm/arm64: Turning IPIs into normal interrupts | expand |
On 5/19/2020 9:17 AM, Marc Zyngier wrote: > For irqchips using the fasteoi flow, IPIs are a bit special. > > They need to be EOId early (before calling the handler), as > funny things may happen in the handler (they do not necessarily > behave like a normal interrupt), and that the arch code is > already handling the stats. > > Signed-off-by: Marc Zyngier <maz@kernel.org> > --- > include/linux/irq.h | 1 + > kernel/irq/chip.c | 26 ++++++++++++++++++++++++++ > 2 files changed, 27 insertions(+) > > diff --git a/include/linux/irq.h b/include/linux/irq.h > index 8d5bc2c237d7..726f94d8b8cc 100644 > --- a/include/linux/irq.h > +++ b/include/linux/irq.h > @@ -621,6 +621,7 @@ static inline int irq_set_parent(int irq, int parent_irq) > */ > extern void handle_level_irq(struct irq_desc *desc); > extern void handle_fasteoi_irq(struct irq_desc *desc); > +extern void handle_percpu_devid_fasteoi_ipi(struct irq_desc *desc); > 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); > diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c > index 41e7e37a0928..7b0b789cfed4 100644 > --- a/kernel/irq/chip.c > +++ b/kernel/irq/chip.c > @@ -955,6 +955,32 @@ void handle_percpu_devid_irq(struct irq_desc *desc) > chip->irq_eoi(&desc->irq_data); > } > > +/** > + * handle_percpu_devid_fasteoi_ipi - Per CPU local IPI handler with per cpu > + * dev ids > + * @desc: the interrupt description structure for this irq > + * > + * The biggest differences with the IRQ version are that: > + * - the interrupt is EOIed early, as the IPI could result in a context > + * switch, and we need to make sure the IPI can fire again > + * - Stats are usually handled at the architecture level, so we ignore them > + * here > + */ > +void handle_percpu_devid_fasteoi_ipi(struct irq_desc *desc) > +{ > + struct irq_chip *chip = irq_desc_get_chip(desc); > + struct irqaction *action = desc->action; > + unsigned int irq = irq_desc_get_irq(desc); > + irqreturn_t res; Should not this have a: if (!irq_settings_is_no_accounting(desc)) __kstat_incr_irqs_this_cpu(desc); here in case you are using that handler with a SGI interrupt which is not used as an IPI? > + > + if (chip->irq_eoi) > + chip->irq_eoi(&desc->irq_data); > + > + trace_irq_handler_entry(irq, action); > + res = action->handler(irq, raw_cpu_ptr(action->percpu_dev_id)); > + trace_irq_handler_exit(irq, action, res); > +} > + > /** > * handle_percpu_devid_fasteoi_nmi - Per CPU local NMI handler with per cpu > * dev ids >
On 19/05/20 17:17, Marc Zyngier wrote: > For irqchips using the fasteoi flow, IPIs are a bit special. > > They need to be EOId early (before calling the handler), as > funny things may happen in the handler (they do not necessarily > behave like a normal interrupt), and that the arch code is > already handling the stats. > > Signed-off-by: Marc Zyngier <maz@kernel.org> > --- > include/linux/irq.h | 1 + > kernel/irq/chip.c | 26 ++++++++++++++++++++++++++ > 2 files changed, 27 insertions(+) > > diff --git a/include/linux/irq.h b/include/linux/irq.h > index 8d5bc2c237d7..726f94d8b8cc 100644 > --- a/include/linux/irq.h > +++ b/include/linux/irq.h > @@ -621,6 +621,7 @@ static inline int irq_set_parent(int irq, int parent_irq) > */ > extern void handle_level_irq(struct irq_desc *desc); > extern void handle_fasteoi_irq(struct irq_desc *desc); > +extern void handle_percpu_devid_fasteoi_ipi(struct irq_desc *desc); > 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); > diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c > index 41e7e37a0928..7b0b789cfed4 100644 > --- a/kernel/irq/chip.c > +++ b/kernel/irq/chip.c > @@ -955,6 +955,32 @@ void handle_percpu_devid_irq(struct irq_desc *desc) > chip->irq_eoi(&desc->irq_data); > } > > +/** > + * handle_percpu_devid_fasteoi_ipi - Per CPU local IPI handler with per cpu > + * dev ids > + * @desc: the interrupt description structure for this irq > + * > + * The biggest differences with the IRQ version are that: > + * - the interrupt is EOIed early, as the IPI could result in a context > + * switch, and we need to make sure the IPI can fire again > + * - Stats are usually handled at the architecture level, so we ignore them > + * here > + */ > +void handle_percpu_devid_fasteoi_ipi(struct irq_desc *desc) > +{ > + struct irq_chip *chip = irq_desc_get_chip(desc); > + struct irqaction *action = desc->action; > + unsigned int irq = irq_desc_get_irq(desc); > + irqreturn_t res; > + Tied to the following patch, does that want something like + if (!irq_settings_is_no_accounting(desc)) + __kstat_incr_irqs_this_cpu(desc); + While I'm at it, now that we would have IPIs as 'normal' interrupts, what prevents us from getting rid of the arch-side accounting? Is it just that we are keeping it as long as handle_IPI() lives, or are there more hurdles hidden around? > + if (chip->irq_eoi) > + chip->irq_eoi(&desc->irq_data); > + > + trace_irq_handler_entry(irq, action); > + res = action->handler(irq, raw_cpu_ptr(action->percpu_dev_id)); > + trace_irq_handler_exit(irq, action, res); > +} > + > /** > * handle_percpu_devid_fasteoi_nmi - Per CPU local NMI handler with per cpu > * dev ids
On 19/05/20 23:25, Valentin Schneider wrote: > Tied to the following patch, does that want something like > > + if (!irq_settings_is_no_accounting(desc)) > + __kstat_incr_irqs_this_cpu(desc); > + And ofc after updating my inbox I see this has already been suggested, oh well.
On Tue, 19 May 2020 12:47:24 -0700 Florian Fainelli <f.fainelli@gmail.com> wrote: > On 5/19/2020 9:17 AM, Marc Zyngier wrote: > > For irqchips using the fasteoi flow, IPIs are a bit special. > > > > They need to be EOId early (before calling the handler), as > > funny things may happen in the handler (they do not necessarily > > behave like a normal interrupt), and that the arch code is > > already handling the stats. > > > > Signed-off-by: Marc Zyngier <maz@kernel.org> > > --- > > include/linux/irq.h | 1 + > > kernel/irq/chip.c | 26 ++++++++++++++++++++++++++ > > 2 files changed, 27 insertions(+) > > > > diff --git a/include/linux/irq.h b/include/linux/irq.h > > index 8d5bc2c237d7..726f94d8b8cc 100644 > > --- a/include/linux/irq.h > > +++ b/include/linux/irq.h > > @@ -621,6 +621,7 @@ static inline int irq_set_parent(int irq, int parent_irq) > > */ > > extern void handle_level_irq(struct irq_desc *desc); > > extern void handle_fasteoi_irq(struct irq_desc *desc); > > +extern void handle_percpu_devid_fasteoi_ipi(struct irq_desc *desc); > > 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); > > diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c > > index 41e7e37a0928..7b0b789cfed4 100644 > > --- a/kernel/irq/chip.c > > +++ b/kernel/irq/chip.c > > @@ -955,6 +955,32 @@ void handle_percpu_devid_irq(struct irq_desc *desc) > > chip->irq_eoi(&desc->irq_data); > > } > > > > +/** > > + * handle_percpu_devid_fasteoi_ipi - Per CPU local IPI handler with per cpu > > + * dev ids > > + * @desc: the interrupt description structure for this irq > > + * > > + * The biggest differences with the IRQ version are that: > > + * - the interrupt is EOIed early, as the IPI could result in a context > > + * switch, and we need to make sure the IPI can fire again > > + * - Stats are usually handled at the architecture level, so we ignore them > > + * here > > + */ > > +void handle_percpu_devid_fasteoi_ipi(struct irq_desc *desc) > > +{ > > + struct irq_chip *chip = irq_desc_get_chip(desc); > > + struct irqaction *action = desc->action; > > + unsigned int irq = irq_desc_get_irq(desc); > > + irqreturn_t res; > > Should not this have a: > > if (!irq_settings_is_no_accounting(desc)) > __kstat_incr_irqs_this_cpu(desc); > > here in case you are using that handler with a SGI interrupt which is > not used as an IPI? I see you coming... ;-) Yes, could do. TBH, I plan on killing the "no accounting" altogether and move to the core IRQ one, so this would only be temporary. All I need is to update the rest of the arm32 interrupt controllers... Thanks, M.
On Tue, 19 May 2020 23:25:43 +0100 Valentin Schneider <valentin.schneider@arm.com> wrote: > On 19/05/20 17:17, Marc Zyngier wrote: > > For irqchips using the fasteoi flow, IPIs are a bit special. > > > > They need to be EOId early (before calling the handler), as > > funny things may happen in the handler (they do not necessarily > > behave like a normal interrupt), and that the arch code is > > already handling the stats. > > > > Signed-off-by: Marc Zyngier <maz@kernel.org> > > --- > > include/linux/irq.h | 1 + > > kernel/irq/chip.c | 26 ++++++++++++++++++++++++++ > > 2 files changed, 27 insertions(+) > > > > diff --git a/include/linux/irq.h b/include/linux/irq.h > > index 8d5bc2c237d7..726f94d8b8cc 100644 > > --- a/include/linux/irq.h > > +++ b/include/linux/irq.h > > @@ -621,6 +621,7 @@ static inline int irq_set_parent(int irq, int parent_irq) > > */ > > extern void handle_level_irq(struct irq_desc *desc); > > extern void handle_fasteoi_irq(struct irq_desc *desc); > > +extern void handle_percpu_devid_fasteoi_ipi(struct irq_desc *desc); > > 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); > > diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c > > index 41e7e37a0928..7b0b789cfed4 100644 > > --- a/kernel/irq/chip.c > > +++ b/kernel/irq/chip.c > > @@ -955,6 +955,32 @@ void handle_percpu_devid_irq(struct irq_desc *desc) > > chip->irq_eoi(&desc->irq_data); > > } > > > > +/** > > + * handle_percpu_devid_fasteoi_ipi - Per CPU local IPI handler with per cpu > > + * dev ids > > + * @desc: the interrupt description structure for this irq > > + * > > + * The biggest differences with the IRQ version are that: > > + * - the interrupt is EOIed early, as the IPI could result in a context > > + * switch, and we need to make sure the IPI can fire again > > + * - Stats are usually handled at the architecture level, so we ignore them > > + * here > > + */ > > +void handle_percpu_devid_fasteoi_ipi(struct irq_desc *desc) > > +{ > > + struct irq_chip *chip = irq_desc_get_chip(desc); > > + struct irqaction *action = desc->action; > > + unsigned int irq = irq_desc_get_irq(desc); > > + irqreturn_t res; > > + > > Tied to the following patch, does that want something like > > + if (!irq_settings_is_no_accounting(desc)) > + __kstat_incr_irqs_this_cpu(desc); > + > > While I'm at it, now that we would have IPIs as 'normal' interrupts, what > prevents us from getting rid of the arch-side accounting? Is it just that > we are keeping it as long as handle_IPI() lives, or are there more hurdles > hidden around? See my reply to Florian. I need to mop the rest of the 32bit irqchips without having the HW (hip04 is almost a copy of the GIC driver, and the Marvell horror is very RPi like). Once this is done, we can kill the home-brewed stuff and rely on core infrastructure. Thanks, M.
diff --git a/include/linux/irq.h b/include/linux/irq.h index 8d5bc2c237d7..726f94d8b8cc 100644 --- a/include/linux/irq.h +++ b/include/linux/irq.h @@ -621,6 +621,7 @@ static inline int irq_set_parent(int irq, int parent_irq) */ extern void handle_level_irq(struct irq_desc *desc); extern void handle_fasteoi_irq(struct irq_desc *desc); +extern void handle_percpu_devid_fasteoi_ipi(struct irq_desc *desc); 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); diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c index 41e7e37a0928..7b0b789cfed4 100644 --- a/kernel/irq/chip.c +++ b/kernel/irq/chip.c @@ -955,6 +955,32 @@ void handle_percpu_devid_irq(struct irq_desc *desc) chip->irq_eoi(&desc->irq_data); } +/** + * handle_percpu_devid_fasteoi_ipi - Per CPU local IPI handler with per cpu + * dev ids + * @desc: the interrupt description structure for this irq + * + * The biggest differences with the IRQ version are that: + * - the interrupt is EOIed early, as the IPI could result in a context + * switch, and we need to make sure the IPI can fire again + * - Stats are usually handled at the architecture level, so we ignore them + * here + */ +void handle_percpu_devid_fasteoi_ipi(struct irq_desc *desc) +{ + struct irq_chip *chip = irq_desc_get_chip(desc); + struct irqaction *action = desc->action; + unsigned int irq = irq_desc_get_irq(desc); + irqreturn_t res; + + if (chip->irq_eoi) + chip->irq_eoi(&desc->irq_data); + + trace_irq_handler_entry(irq, action); + res = action->handler(irq, raw_cpu_ptr(action->percpu_dev_id)); + trace_irq_handler_exit(irq, action, res); +} + /** * handle_percpu_devid_fasteoi_nmi - Per CPU local NMI handler with per cpu * dev ids
For irqchips using the fasteoi flow, IPIs are a bit special. They need to be EOId early (before calling the handler), as funny things may happen in the handler (they do not necessarily behave like a normal interrupt), and that the arch code is already handling the stats. Signed-off-by: Marc Zyngier <maz@kernel.org> --- include/linux/irq.h | 1 + kernel/irq/chip.c | 26 ++++++++++++++++++++++++++ 2 files changed, 27 insertions(+)