[PATCH 0/5] Threaded MSI interrupt for VFIO PCI device

Yunhong Jiang
2015-12-03T18:36:49Z

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(-)

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1.8.3.1