kvm/x86: Hyper-V SynIC message slot pending clearing at SINT ack
authorAndrey Smetanin <asmetanin@virtuozzo.com>
Mon, 30 Nov 2015 16:22:20 +0000 (19:22 +0300)
committerPaolo Bonzini <pbonzini@redhat.com>
Wed, 16 Dec 2015 17:49:44 +0000 (18:49 +0100)
commit765eaa0f70eaa274ec8b815d8c210c20cf7b6dbc
tree5eda792ac2977dd37b16b8a6268acd0abc14ea11
parent93bf4172481c4b2a8544c83a687946252563edd0
kvm/x86: Hyper-V SynIC message slot pending clearing at SINT ack

The SynIC message protocol mandates that the message slot is claimed
by atomically setting message type to something other than HVMSG_NONE.
If another message is to be delivered while the slot is still busy,
message pending flag is asserted to indicate to the guest that the
hypervisor wants to be notified when the slot is released.

To make sure the protocol works regardless of where the message
sources are (kernel or userspace), clear the pending flag on SINT ACK
notification, and let the message sources compete for the slot again.

Signed-off-by: Andrey Smetanin <asmetanin@virtuozzo.com>
Reviewed-by: Roman Kagan <rkagan@virtuozzo.com>
CC: Gleb Natapov <gleb@kernel.org>
CC: Paolo Bonzini <pbonzini@redhat.com>
CC: "K. Y. Srinivasan" <kys@microsoft.com>
CC: Haiyang Zhang <haiyangz@microsoft.com>
CC: Vitaly Kuznetsov <vkuznets@redhat.com>
CC: Roman Kagan <rkagan@virtuozzo.com>
CC: Denis V. Lunev <den@openvz.org>
CC: qemu-devel@nongnu.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
arch/x86/kvm/hyperv.c
include/linux/kvm_host.h