path: root/kernel
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authorLinus Torvalds <torvalds@linux-foundation.org>2017-11-13 18:29:23 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2017-11-13 18:29:23 -0800
commitb18d62891aaff49d0ee8367d4b6bb9452469f807 (patch)
tree02508b3602ff667a20cd107a5125ca5e57ce6806 /kernel
parent7d58e1c9059eefe0066c5acf2ffa582f6f0180e3 (diff)
parent141d3b1daacd11bdbd6fa74c2b163093e10d17ee (diff)
Merge branch 'x86-apic-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 APIC updates from Thomas Gleixner: "This update provides a major overhaul of the APIC initialization and vector allocation code: - Unification of the APIC and interrupt mode setup which was scattered all over the place and was hard to follow. This also distangles the timer setup from the APIC initialization which brings a clear separation of functionality. Great detective work from Dou Lyiang! - Refactoring of the x86 vector allocation mechanism. The existing code was based on nested loops and rather convoluted APIC callbacks which had a horrible worst case behaviour and tried to serve all different use cases in one go. This led to quite odd hacks when supporting the new managed interupt facility for multiqueue devices and made it more or less impossible to deal with the vector space exhaustion which was a major roadblock for server hibernation. Aside of that the code dealing with cpu hotplug and the system vectors was disconnected from the actual vector management and allocation code, which made it hard to follow and maintain. Utilizing the new bitmap matrix allocator core mechanism, the new allocator and management code consolidates the handling of system vectors, legacy vectors, cpu hotplug mechanisms and the actual allocation which needs to be aware of system and legacy vectors and hotplug constraints into a single consistent entity. This has one visible change: The support for multi CPU targets of interrupts, which is only available on a certain subset of CPUs/APIC variants has been removed in favour of single interrupt targets. A proper analysis of the multi CPU target feature revealed that there is no real advantage as the vast majority of interrupts end up on the CPU with the lowest APIC id in the set of target CPUs anyway. That change was agreed on by the relevant folks and allowed to simplify the implementation significantly and to replace rather fragile constructs like the vector cleanup IPI with straight forward and solid code. Furthermore this allowed to cleanly separate the allocation details for legacy, normal and managed interrupts: * Legacy interrupts are not longer wasting 16 vectors unconditionally * Managed interrupts have now a guaranteed vector reservation, but the actual vector assignment happens when the interrupt is requested. It's guaranteed not to fail. * Normal interrupts no longer allocate vectors unconditionally when the interrupt is set up (IO/APIC init or MSI(X) enable). The mechanism has been switched to a best effort reservation mode. The actual allocation happens when the interrupt is requested. Contrary to managed interrupts the request can fail due to vector space exhaustion, but drivers must handle a fail of request_irq() anyway. When the interrupt is freed, the vector is handed back as well. This solves a long standing problem with large unconditional vector allocations for a certain class of enterprise devices which prevented server hibernation due to vector space exhaustion when the unused allocated vectors had to be migrated to CPU0 while unplugging all non boot CPUs. The code has been equipped with trace points and detailed debugfs information to aid analysis of the vector space" * 'x86-apic-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (60 commits) x86/vector/msi: Select CONFIG_GENERIC_IRQ_RESERVATION_MODE PCI/MSI: Set MSI_FLAG_MUST_REACTIVATE in core code genirq: Add config option for reservation mode x86/vector: Use correct per cpu variable in free_moved_vector() x86/apic/vector: Ignore set_affinity call for inactive interrupts x86/apic: Fix spelling mistake: "symmectic" -> "symmetric" x86/apic: Use dead_cpu instead of current CPU when cleaning up ACPI/init: Invoke early ACPI initialization earlier x86/vector: Respect affinity mask in irq descriptor x86/irq: Simplify hotplug vector accounting x86/vector: Switch IOAPIC to global reservation mode x86/vector/msi: Switch to global reservation mode x86/vector: Handle managed interrupts proper x86/io_apic: Reevaluate vector configuration on activate() iommu/amd: Reevaluate vector configuration on activate() iommu/vt-d: Reevaluate vector configuration on activate() x86/apic/msi: Force reactivation of interrupts at startup time x86/vector: Untangle internal state from irq_cfg x86/vector: Compile SMP only code conditionally x86/apic: Remove unused callbacks ...
Diffstat (limited to 'kernel')
1 files changed, 3 insertions, 0 deletions
diff --git a/kernel/irq/Kconfig b/kernel/irq/Kconfig
index ac1a3e29d3b9..89e355866450 100644
--- a/kernel/irq/Kconfig
+++ b/kernel/irq/Kconfig
@@ -100,6 +100,9 @@ config IRQ_TIMINGS
+ bool
bool "Expose hardware/virtual IRQ mapping via debugfs"
depends on IRQ_DOMAIN && DEBUG_FS