MFC 347033:
Increase the VirtIO segment count to support modern Windows guests.

The Windows virtio driver ignores the advertized seg_max field and
assumes the host can accept up to 67 segments in indirect descriptors,
triggering an assert in the bhyve process.

This brings back r282922 but with a couple of changes:
- It raises the block interface segment limit to 128 instead of 67.
- Linux's virtio driver assumes that the segment limit is no
larger than the ring size. To avoid breaking Linux guests,
raise the VirtIO ring size to 128, and cap the VirtIO segment
limit at ring size - 2 (effectively 126).

Approved by: re (gjb)

MFC r326276:

various: general adoption of SPDX licensing ID tags.

Mainly focus on files that use BSD 2-Clause license, however the tool I
was using misidentified many licenses so this was mostly a manual - error
prone - task.

The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.

No functional change intended.

Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Temporarily revert r282922 which bumped the max descriptors.

While there is no issued with the number of descriptors in
a virtio indirect descriptor, it's a guest's choice as to
whether indirect descriptors are used. For the case where
they aren't, the virtio block ring size is still 64 which
is less than the now reported max_segs of 67. This results
in an assertion in recent Linux guests even though it was
benign since they were using indirect descs.

The intertwined relationship between virtio ring size,
max seg size and blockif queue size will be addressed
in an upcoming commit, at which point the max descriptors
will again be bumped up to 67.

Bump the size of the blockif scatter-gather list to 67.

The Windows virtio driver ignores the advertized seg_max
field and assumes the host can accept up to 67 segments
in indirect descriptors, triggering an assert in the bhyve
process.

No objection from: mav
Reviewed by: neel
Reported and tested by: Leon Dang (ldang@nahannisys.com)
MFC after: 2 weeks

Workaround bhyve virtual disks operation on top of GEOM providers.

GEOM does not support scatter/gather lists in its I/Os. Such requests
are cut in pieces by physio(), that may be problematic, if those pieces
are not multiple of provider's sector size. If such case is detected,
move the data through temporary sequential buffer.

MFC after: 2 weeks

Increase S/G list size of 32 to 33 entries.

32 entries are not enough for the worst case of misaligned 128KB request,
that made FreeBSD to chunk large quests in odd pieces.

MFC after: 2 weeks

Add DSM TRIM command support for virtual AHCI disks.

It works only for virtual disks backed by ZVOLs and raw devices supporting
BIO_DELETE. Virtual disks backed by files won't report this capability.

MFC after: 2 weeks
Relnotes: yes

Report logical/physical sector sizes for virtual SATA disk.

MFC after: 2 weeks

Add a call to synthesize a C/H/S value for block emulations
that require it (ahci). The algorithm used is from the VHD
specification.

Block-layer backend interface for bhyve block-io device emulations.

Approved by: re@ (blanket)