MFC 295748,295792,295793,295794

MFC 295748,295792,295793,295794

295748
    hyperv/hn: Use buf_ring for txdesc list

    So one spinlock is avoided, which would be potentially dangerous for
    virtual machine, if the spinlock holder was scheduled out by the host,
    as noted by royger.

    Old spinlock based txdesc list is still kept around, so we could have
    a safe fallback.

    No performance regression nor improvement is observed.

    Reviewed by:        adrian
    Approved by:        adrian (mentor)
    MFC after:  1 week
    Sponsored by:       Microsoft OSTC
    Differential Revision:      https://reviews.freebsd.org/D5290

295792
    hyperv/hn: Add option to bind TX taskqueues to the specified CPU

    It will be used to help tracking host side transmission ring selection
    issue; and it will be turned on by default, once we have concrete result.

    Reviewed by:        adrian, Jun Su <junsu microsoft com>
    Approved by:        adrian (mento)
    MFC after:  1 week
    Sponsored by:       Microsoft OSTC
    Differential Revision:      https://reviews.freebsd.org/D5316

295793
    hyperv/hn: Enable IP header checksum offloading for WIN8 (WinServ2012)

    Tested on Windows Server 2012.

    Reviewed by:        adrian
    Approved by:        adrian (mentor)
    MFC after:  1 week
    Sponsored by:       Microsoft OSTC
    Differential Revision:      https://reviews.freebsd.org/D5317

295794
    hyperv/hn: Free the txdesc buf_ring when the TX ring is destroyed

    Reviewed by:        adrian
    Approved by:        adrian (mentor)
    MFC after:  1 week
    Sponsored by:       Microsoft OSTC
    Differential Revision:      https://reviews.freebsd.org/D5318

git-svn-id: svn://svn.freebsd.org/base/stable/10@301862 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f