- Copy stable/10@296371 to releng/10.3 in preparation for 10.3-RC1
builds.
- Update newvers.sh to reflect RC1.
- Update __FreeBSD_version to reflect 10.3.
- Update default pkg(8) configuration to use the quarterly branch.

Approved by: re (implicit)

MFC r281254:
Account for the offset of the page run when allocating the
dmar_map_entry.

MFC r280435:
When mapping an allocated entry, use the entry size, instead of the
requested size. If tag restrictions caused split entry, its size is
less then requsted.

MFC r280196:
Recheck that boundary is not crossed after the move to satisfy boundary
restriction.

MFC r280195:
When inserting new entry into the address map, ensure that not only
next entry does not intersect with the tail of the new entry, but also
that previous entry is also before new entry start.

MFC DMAR busdma implementation.

MFC r257251:
Import the driver for VT-d DMAR hardware. Implement the busdma(9) using DMARs.

MFC r257512:
Add support for queued invalidation.

MFC miscellaneous follow-ups to r257251.

MFC r257266:
Remove redundand assignment to error variable and check for its value.

MFC r257308:
Remove redundand declaration.

MFC r257511:
Return BUS_PROBE_NOWILDCARD from the DMAR probe method.

MFC r257860,r257896,r257900,r257902,r257903 (by dim):
Fixes for gcc compilation.

Import the driver for VT-d DMAR hardware, as specified in the revision
1.3 of Intelб╝ Virtualization Technology for Directed I/O Architecture
Specification. The Extended Context and PASIDs from the rev. 2.2 are
not supported, but I am not aware of any released hardware which
implements them. Code does not use queued invalidation, see comments
for the reason, and does not provide interrupt remapping services.

Code implements the management of the guest address space per domain
and allows to establish and tear down arbitrary mappings, but not
partial unmapping. The superpages are created as needed, but not
promoted. Faults are recorded, fault records could be obtained
programmatically, and printed on the console.

Implement the busdma(9) using DMARs. This busdma backend avoids
bouncing and provides security against misbehaving hardware and driver
bad programming, preventing leaks and corruption of the memory by wild
DMA accesses.

By default, the implementation is compiled into amd64 GENERIC kernel
but disabled; to enable, set hw.dmar.enable=1 loader tunable. Code is
written to work on i386, but testing there was low priority, and
driver is not enabled in GENERIC. Even with the DMAR turned on,
individual devices could be directed to use the bounce busdma with the
hw.busdma.pci<domain>:<bus>:<device>:<function>.bounce=1 tunable. If
DMARs are capable of the pass-through translations, it is used,
otherwise, an identity-mapping page table is constructed.

The driver was tested on Xeon 5400/5500 chipset legacy machine,
Haswell desktop and E5 SandyBridge dual-socket boxes, with ahci(4),
ata(4), bce(4), ehci(4), mfi(4), uhci(4), xhci(4) devices. It also
works with em(4) and igb(4), but there some fixes are needed for
drivers, which are not committed yet. Intel GPUs do not work with
DMAR (yet).

Many thanks to John Baldwin, who explained me the newbus integration;
Peter Holm, who did all testing and helped me to discover and
understand several incredible bugs; and to Jim Harris for the access
to the EDS and BWG and for listening when I have to explain my
findings to somebody.

Sponsored by: The FreeBSD Foundation
MFC after: 1 month