[PATCH v2 0/1] x86/kvm/hyper-v: Add support to SYNIC exit on EOM

[Jon Doron <arilou@gmail.com>]

According to the TLFS:
"A write to the end of message (EOM) register by the guest causes the
hypervisor to scan the internal message buffer queue(s) associated with
the virtual processor.

If a message buffer queue contains a queued message buffer, the hypervisor
attempts to deliver the message.

Message delivery succeeds if the SIM page is enabled and the message slot
corresponding to the SINTx is empty (that is, the message type in the
header is set to HvMessageTypeNone).
If a message is successfully delivered, its corresponding internal message
buffer is dequeued and marked free.
If the corresponding SINTx is not masked, an edge-triggered interrupt is
delivered (that is, the corresponding bit in the IRR is set).

This register can be used by guests to poll for messages. It can also be
used as a way to drain the message queue for a SINTx that has
been disabled (that is, masked)."

So basically this means that we need to exit on EOM so the hypervisor
will have a chance to send all the pending messages regardless of the
SCONTROL mechnaisim.

v2:
Minor fixes from code review

Jon Doron (1):
  x86/kvm/hyper-v: Add support to SYNIC exit on EOM

 arch/x86/include/asm/kvm_host.h |  1 +
 arch/x86/kvm/hyperv.c           | 67 +++++++++++++++++++++++++++++----
 arch/x86/kvm/hyperv.h           |  1 +
 arch/x86/kvm/x86.c              |  5 +++
 include/uapi/linux/kvm.h        |  1 +
 5 files changed, 67 insertions(+), 8 deletions(-)

-- 
2.24.1