Jan Kiszka wrote:
> Jan Kiszka wrote:
>> Currently, I-pipe breaks the setting of IRQ affinities through Linux,
>> the root domain. This is because migrating IRQs while they are active is
>> a tricky business on x86, requiring special measures within the IRQ ack
>> path. And as this path is now used by non-root domains, the migration
>> code had to be deactivated.
>>
>> The following patch is a proof of concept for x86-64 how to overcome
>> this unfortunate limitation (if you want to isolate RT from non-RT
>> CPUs). The approach works without adding code to critical paths. First
>> tests inside KVM indicate that things work as expected, but more testing
>> on real iron is scheduled, e.g. to check MSI IRQs which I don't have in
>> my KVM environment.
>>
>
> Here is version 2, now also including 32-bit support (untested).
>
> Meanwhile I've run this patch on an real dual core box with MSI, and all
> works smoothly.
>
The idea looks good in any case. I will merge this next week unless a problem
arises during testing. Thanks,
> Jan
> ---
> arch/x86/kernel/io_apic_32.c | 24 ++++++++++++++++++++++++
> arch/x86/kernel/io_apic_64.c | 42
> +++++++++++++++++++++++++++++++++++++-----
> include/asm-x86/ipipe.h | 11 +++++++++++
> include/asm-x86/ipipe_64.h | 5 +++--
> include/linux/irq.h | 3 +++
> 5 files changed, 78 insertions(+), 7 deletions(-)
>
> Index: b/arch/x86/kernel/io_apic_64.c
> ===================================================================
> --- a/arch/x86/kernel/io_apic_64.c
> +++ b/arch/x86/kernel/io_apic_64.c
> @@ -174,7 +174,6 @@ static inline void io_apic_modify(unsign
> writel(value, &io_apic->data);
> }
>
> -#ifndef CONFIG_IPIPE
> static bool io_apic_level_ack_pending(unsigned int irq)
> {
> struct irq_pin_list *entry;
> @@ -203,7 +202,6 @@ static bool io_apic_level_ack_pending(un
>
> return false;
> }
> -#endif /* !CONFIG_IPIPE */
>
> /*
> * Synchronize the IO-APIC and the CPU by doing
> @@ -1436,7 +1434,6 @@ unlock:
> irq_exit();
> }
>
> -#ifndef CONFIG_IPIPE
> static void irq_complete_move(unsigned int irq)
> {
> struct irq_cfg *cfg = irq_cfg + irq;
> @@ -1456,11 +1453,34 @@ static void irq_complete_move(unsigned i
> cfg->move_in_progress = 0;
> }
> }
> -#endif
> -#elif !defined(CONFIG_IPIPE)
> +#else
> static inline void irq_complete_move(unsigned int irq) {}
> #endif
>
> +#ifdef CONFIG_IPIPE
> +static void move_apic_irq(unsigned int irq)
> +{
> + struct irq_desc *desc = &irq_desc[irq];
> +
> + if (desc->handle_irq == &handle_edge_irq) {
> + spin_lock(&desc->lock);
> + irq_complete_move(irq);
> + move_native_irq(irq);
> + spin_unlock(&desc->lock);
> + } else if (desc->handle_irq == &handle_fasteoi_irq) {
> + spin_lock(&desc->lock);
> + irq_complete_move(irq);
> + if (unlikely(desc->status & IRQ_MOVE_PENDING)) {
> + if (!io_apic_level_ack_pending(irq))
> + move_masked_irq(irq);
> + unmask_IO_APIC_irq(irq);
> + }
> + spin_unlock(&desc->lock);
> + } else
> + WARN_ON_ONCE(1);
> +}
> +#endif /* CONFIG_IPIPE */
> +
> static void ack_apic_edge(unsigned int irq)
> {
> #ifndef CONFIG_IPIPE
> @@ -1544,6 +1564,9 @@ static struct irq_chip ioapic_chip __rea
> .eoi = ack_apic_level,
> #ifdef CONFIG_SMP
> .set_affinity = set_ioapic_affinity_irq,
> +#ifdef CONFIG_IPIPE
> + .move = move_apic_irq,
> +#endif
> #endif
> .retrigger = ioapic_retrigger_irq,
> };
> @@ -2087,6 +2110,9 @@ static struct irq_chip msi_chip = {
> .ack = ack_apic_edge,
> #ifdef CONFIG_SMP
> .set_affinity = set_msi_irq_affinity,
> +#ifdef CONFIG_IPIPE
> + .move = move_apic_irq,
> +#endif
> #endif
> .retrigger = ioapic_retrigger_irq,
> };
> @@ -2156,6 +2182,9 @@ struct irq_chip dmar_msi_type = {
> .ack = ack_apic_edge,
> #ifdef CONFIG_SMP
> .set_affinity = dmar_msi_set_affinity,
> +#ifdef CONFIG_IPIPE
> + .move = move_apic_irq,
> +#endif
> #endif
> .retrigger = ioapic_retrigger_irq,
> };
> @@ -2225,6 +2254,9 @@ static struct irq_chip ht_irq_chip = {
> .ack = ack_apic_edge,
> #ifdef CONFIG_SMP
> .set_affinity = set_ht_irq_affinity,
> +#ifdef CONFIG_IPIPE
> + .move = move_apic_irq,
> +#endif
> #endif
> .retrigger = ioapic_retrigger_irq,
> };
> Index: b/include/asm-x86/ipipe_64.h
> ===================================================================
> --- a/include/asm-x86/ipipe_64.h
> +++ b/include/asm-x86/ipipe_64.h
> @@ -144,10 +144,11 @@ static inline void __ipipe_call_root_vir
> do { \
> local_irq_enable_nohead(ipd); \
> if (ipd == ipipe_root_domain) { \
> - if (likely(!ipipe_virtual_irq_p(irq))) \
> + if (likely(!ipipe_virtual_irq_p(irq))) { \
> + __ipipe_move_root_irq(irq); \
> __ipipe_call_root_xirq_handler( \
> irq, (ipd)->irqs[irq].handler); \
> - else \
> + } else \
> __ipipe_call_root_virq_handler( \
> irq, (ipd)->irqs[irq].handler, \
> (ipd)->irqs[irq].cookie); \
> Index: b/include/linux/irq.h
> ===================================================================
> --- a/include/linux/irq.h
> +++ b/include/linux/irq.h
> @@ -111,6 +111,9 @@ struct irq_chip {
>
> void (*end)(unsigned int irq);
> void (*set_affinity)(unsigned int irq, cpumask_t dest);
> +#ifdef CONFIG_IPIPE
> + void (*move)(unsigned int irq);
> +#endif /* CONFIG_IPIPE */
> int (*retrigger)(unsigned int irq);
> int (*set_type)(unsigned int irq, unsigned int flow_type);
> int (*set_wake)(unsigned int irq, unsigned int on);
> Index: b/arch/x86/kernel/io_apic_32.c
> ===================================================================
> --- a/arch/x86/kernel/io_apic_32.c
> +++ b/arch/x86/kernel/io_apic_32.c
> @@ -1929,6 +1929,21 @@ static unsigned int startup_ioapic_irq(u
> return was_pending;
> }
>
> +#if defined(CONFIG_IPIPE) && defined(CONFIG_SMP)
> +static void move_apic_irq(unsigned int irq)
> +{
> + struct irq_desc *desc = &irq_desc[irq];
> +
> + if (desc->handle_irq == &handle_edge_irq ||
> + desc->handle_irq == &handle_fasteoi_irq) {
> + spin_lock(&desc->lock);
> + move_native_irq(irq);
> + spin_unlock(&desc->lock);
> + } else
> + WARN_ON_ONCE(1);
> +}
> +#endif /* CONFIG_IPIPE && CONFIG_SMP */
> +
> static void ack_ioapic_irq(unsigned int irq)
> {
> #ifndef CONFIG_IPIPE
> @@ -2018,6 +2033,9 @@ static struct irq_chip ioapic_chip __rea
> .eoi = ack_ioapic_quirk_irq,
> #ifdef CONFIG_SMP
> .set_affinity = set_ioapic_affinity_irq,
> +#ifdef CONFIG_IPIPE
> + .move = move_apic_irq,
> +#endif
> #endif
> .retrigger = ioapic_retrigger_irq,
> };
> @@ -2600,6 +2618,9 @@ static struct irq_chip msi_chip = {
> .ack = ack_ioapic_irq,
> #ifdef CONFIG_SMP
> .set_affinity = set_msi_irq_affinity,
> +#ifdef CONFIG_IPIPE
> + .move = move_apic_irq,
> +#endif
> #endif
> .retrigger = ioapic_retrigger_irq,
> };
> @@ -2680,6 +2701,9 @@ static struct irq_chip ht_irq_chip = {
> .ack = ack_ioapic_irq,
> #ifdef CONFIG_SMP
> .set_affinity = set_ht_irq_affinity,
> +#ifdef CONFIG_IPIPE
> + .move = move_apic_irq,
> +#endif
> #endif
> .retrigger = ioapic_retrigger_irq,
> };
> Index: b/include/asm-x86/ipipe.h
> ===================================================================
> --- a/include/asm-x86/ipipe.h
> +++ b/include/asm-x86/ipipe.h
> @@ -118,6 +118,17 @@ int __ipipe_check_tickdev(const char *de
>
> #define __ipipe_root_tick_p(regs) ((regs)->flags & X86_EFLAGS_IF)
>
> +#ifdef CONFIG_SMP
> +#define __ipipe_move_root_irq(irq) \
> + do { \
> + struct irq_chip *chip = irq_desc[irq].chip; \
> + if (irq < NR_IRQS && chip->move) \
> + chip->move(irq); \
> + } while (0)
> +#else /* !CONFIG_SMP */
> +#define __ipipe_move_root_irq(irq) do { } while (0)
> +#endif /* !CONFIG_SMP */
> +
> #else /* !CONFIG_IPIPE */
>
> #define ipipe_update_tick_evtdev(evtdev) do { } while (0)
>
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>
--
Philippe.
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