This patch introduces the host "Virtio over PCIe" interface for
Intel MIC. It allows creating user space backends on the host and instantiating
virtio devices for them on the Intel MIC card. It uses the existing VRINGH
infrastructure in the kernel to access virtio rings from the host. A character
device per MIC is exposed with IOCTL, mmap and poll callbacks. This allows the
user space backend to:
(a) add/remove a virtio device via a device page.
(b) map (R/O) virtio rings and device page to user space.
(c) poll for availability of data.
(d) copy a descriptor or entire descriptor chain to/from the card.
(e) modify virtio configuration.
(f) handle virtio device reset.
The buffers are copied over using CPU copies for this initial patch
and host initiated MIC DMA support is planned for future patches.
The avail and desc virtio rings are in host memory and the used ring
is in card memory to maximize writes across PCIe for performance.

Co-author: Sudeep Dutt <sudeep.dutt@intel.com>
Signed-off-by: NAshutosh Dixit <ashutosh.dixit@intel.com>
Signed-off-by: NCaz Yokoyama <Caz.Yokoyama@intel.com>
Signed-off-by: NDasaratharaman Chandramouli <dasaratharaman.chandramouli@intel.com>
Signed-off-by: NNikhil Rao <nikhil.rao@intel.com>
Signed-off-by: NHarshavardhan R Kharche <harshavardhan.r.kharche@intel.com>
Signed-off-by: NSudeep Dutt <sudeep.dutt@intel.com>
Acked-by: NYaozu (Eddie) Dong <eddie.dong@intel.com>
Reviewed-by: NPeter P Waskiewicz Jr <peter.p.waskiewicz.jr@intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This patch enables the following features:
a) Boots and shuts down the card via sysfs entries.
b) Allocates and maps a device page for communication with the
   card driver and updates the device page address via scratchpad
   registers.
c) Provides sysfs entries for shutdown status, kernel command line,
   ramdisk and log buffer information.

Co-author: Dasaratharaman Chandramouli <dasaratharaman.chandramouli@intel.com>
Signed-off-by: NAshutosh Dixit <ashutosh.dixit@intel.com>
Signed-off-by: NCaz Yokoyama <Caz.Yokoyama@intel.com>
Signed-off-by: NDasaratharaman Chandramouli <dasaratharaman.chandramouli@intel.com>
Signed-off-by: NHarshavardhan R Kharche <harshavardhan.r.kharche@intel.com>
Signed-off-by: NNikhil Rao <nikhil.rao@intel.com>
Signed-off-by: NSudeep Dutt <sudeep.dutt@intel.com>
Acked-by: NYaozu (Eddie) Dong <eddie.dong@intel.com>
Reviewed-by: NPeter P Waskiewicz Jr <peter.p.waskiewicz.jr@intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>