vfio: Support host translation granule size

vfio: Support host translation granule size

The cpu_physical_memory_set_dirty_lebitmap() can quickly deal with
the dirty pages of memory by bitmap-traveling, regardless of whether
the bitmap is aligned correctly or not.

cpu_physical_memory_set_dirty_lebitmap() supports pages in bitmap of
host page size. So it'd better to set bitmap_pgsize to host page size
to support more translation granule sizes.

[aw: The Fixes commit below introduced code to restrict migration
support to configurations where the target page size intersects the
host dirty page support.  For example, a 4K guest on a 4K host.
Due to the above flexibility in bitmap handling, this restriction
unnecessarily prevents mixed target/host pages size that could
otherwise be supported.  Use host page size for dirty bitmap.]

Fixes: 87ea529c502 ("vfio: Get migration capability flags for container")
Signed-off-by: Kunkun Jiang <jiangkunkun@huawei.com>
Message-Id: <20210304133446.1521-1-jiangkunkun@huawei.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>