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

[Yunhong Jiang <yunhong.jiang@linux.intel.com>]

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