[PATCH V4 0/4] Fast MMIO eventfd fixes

[Jason Wang]

Hi:

This series fixes two issues of fast mmio eventfd:

1) A single iodev instance were registerd on two buses: KVM_MMIO_BUS
   and KVM_FAST_MMIO_BUS. This will cause double in
   ioeventfd_destructor()
2) A zero length iodev on KVM_MMIO_BUS will never be found but
   kvm_io_bus_cmp(). This will lead e.g the eventfd will be trapped by
   qemu instead of host.

1 is fixed by allocating two instances of iodev. 2 is fixed by ignore
the actual length if the length of iodev is zero in kvm_io_bus_cmp().

Please review.

Changes from V3:

- Don't do search on two buses when trying to do write on
  KVM_MMIO_BUS. This fixes a small regression found by vmexit.flat.
- Since we don't do search on two buses, change kvm_io_bus_cmp() to
  let it can find zero length iodevs.
- Fix the unnecessary lines in tracepoint patch.

Changes from V2:
- Tweak styles and comment suggested by Cornelia.

Changes from v1:
- change ioeventfd_bus_from_flags() to return KVM_FAST_MMIO_BUS when
  needed to save lots of unnecessary changes.

Jason Wang (4):
  kvm: factor out core eventfd assign/deassign logic
  kvm: fix double free for fast mmio eventfd
  kvm: fix zero length mmio searching
  kvm: add tracepoint for fast mmio

 arch/x86/kvm/trace.h |  18 ++++++++
 arch/x86/kvm/vmx.c   |   1 +
 arch/x86/kvm/x86.c   |   1 +
 virt/kvm/eventfd.c   | 124 ++++++++++++++++++++++++++++++---------------------
 virt/kvm/kvm_main.c  |   4 +-
 5 files changed, 96 insertions(+), 52 deletions(-)

-- 
2.1.4

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