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    SubjectRe: [PATCH v6 0/2] kvm: level irqfd and new eoifd
    On Fri, 2012-07-20 at 10:33 -0600, Alex Williamson wrote:
    > v6:
    > So we're back to just the first two patches, unfortunately the
    > diffstat got bigger though. The reason for that is that I discovered
    > we don't do anything on release of an eoifd. We cleanup if the kvm
    > vm is released, but we're dealing with a constrained resource of irq
    > source IDs, so I think it's best that we cleanup to make sure those
    > are returned. To do that we need nearly the same infrastructure as
    > irqfd, we just only watch for POLLHUP. So while there's more code
    > here, the structure and function names line up identically to irqfd.
    > The other big change here is that KVM_IRQFD returns a token when
    > setting up a level irqfd. We use this token to associate the eoifd
    > with the right source. This means we have to put the struct
    > _source_ids on a list so we can find them. This removes the weird
    > interaction we were headed to where the eoifd is associated with
    > the eventfd of the irqfd. There's potentially more flexibility for
    > the future here too as we might come up with other interfaces that
    > can return a source ID "key". Perhaps some future KVM_IRQFD will
    > allow specifying a key for re-attaching. Anyway, the sequence
    > Michael pointed out where an irqfd is de-assigned then re-assigned
    > now results in a new key instead of leaving the user wondering if
    > it re-associates back to the eoifd.
    > Also added workqueue flushes on assign since releasing either
    > object now results in a lazy release via workqueue. This ensures
    > we re-claim any source IDs we can. Thanks,

    FYI, I seem to have found a new locking issue in this version. I'll
    send an update when I find it. Thanks,


    > ---
    > Alex Williamson (2):
    > kvm: KVM_EOIFD, an eventfd for EOIs
    > kvm: Extend irqfd to support level interrupts
    > Documentation/virtual/kvm/api.txt | 32 ++-
    > arch/x86/kvm/x86.c | 3
    > include/linux/kvm.h | 18 +
    > include/linux/kvm_host.h | 17 +
    > virt/kvm/eventfd.c | 463 ++++++++++++++++++++++++++++++++++++-
    > virt/kvm/kvm_main.c | 11 +
    > 6 files changed, 536 insertions(+), 8 deletions(-)

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