When assigning a VFIO device to a KVM guest with low latency requirement, it is better to handle the interrupt in the hard interrupt context, to reduce the context switch to/from the IRQ thread. Based on discussion on https://lkml.org/lkml/2015/10/26/764, the VFIO msi interrupt is changed to use request_threaded_irq(). The primary interrupt handler tries to set the guest interrupt atomically. If it fails to achieve it, a threaded interrupt handler will be invoked. The irq_bypass manager is extended for this purpose. The KVM eventfd will provide a irqbypass consumer to handle the interrupt at hard interrupt context. The producer will invoke the consumer's handler then. Yunhong Jiang (5): Extract the irqfd_wakeup_pollin/irqfd_wakeup_pollup Support runtime irq_bypass consumer Support threaded interrupt handling on VFIO Add the irq handling consumer Expose x86 kvm_arch_set_irq_inatomic() arch/x86/kvm/Kconfig | 1 + drivers/vfio/pci/vfio_pci_intrs.c | 39 ++++++++++-- include/linux/irqbypass.h | 8 +++ include/linux/kvm_host.h | 19 +++++- include/linux/kvm_irqfd.h | 1 + virt/kvm/Kconfig | 3 + virt/kvm/eventfd.c | 131 ++++++++++++++++++++++++++------------ virt/lib/irqbypass.c | 82 ++++++++++++++++++------ 8 files changed, 214 insertions(+), 70 deletions(-) -- 1.8.3.1 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
