sys: Remove $FreeBSD$: two-line .h pattern

Remove /^\s*\*\n \*\s+\$FreeBSD\$$\n/

spdx: The BSD-2-Clause-FreeBSD identifier is obsolete, drop -FreeBSD

The SPDX folks have obsoleted the BSD-2-Clause-FreeBSD identifier. Catch
up to that fact and revert to their recommended match of BSD-2-Clause.

Discussed with: pfg
MFC After: 3 days
Sponsored by: Netflix

x86/xen: remove PVHv1 code

PVHv1 was officially removed from Xen in 4.9, so just axe the related
code from FreeBSD.

Note FreeBSD supports PVHv2, which is the replacement for PVHv1.

Sponsored by: Citrix Systems R&D
Reviewed by: kib, Elliott Mitchell
Differential Revision: https://reviews.freebsd.org/D30228

x86: improve reservation of AP trampoline memory

So that it doesn't rely on physmap[1] containing an address below
1MiB. Instead scan the full physmap and search for a suitable address
to place the trampoline code (below 1MiB) and the initial memory pages
(below 4GiB).

Sponsored by: Citrix Systems R&D
Reviewed by: kib
Differential Revision: https://reviews.freebsd.org/D14878

sys/x86: further 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.

msi: add Xen MSI implementation

This patch adds support for MSI interrupts when running on Xen. Apart
from adding the Xen related code needed in order to register MSI
interrupts this patch also makes the msi_init function a hook in
init_ops, so different MSI implementations can have different
initialization functions.

Sponsored by: Citrix Systems R&D

xen/interface/physdev.h:
- Add the MAP_PIRQ_TYPE_MULTI_MSI to map multi-vector MSI to the Xen
public interface.

x86/include/init.h:
- Add a hook for setting custom msi_init methods.

amd64/amd64/machdep.c:
i386/i386/machdep.c:
- Set the default msi_init hook to point to the native MSI
initialization method.

x86/xen/pv.c:
- Set the Xen MSI init hook when running as a Xen guest.

x86/x86/local_apic.c:
- Call the msi_init hook instead of directly calling msi_init.

xen/xen_intr.h:
x86/xen/xen_intr.c:
- Introduce support for registering/releasing MSI interrupts with
Xen.
- The MSI interrupts will use the same PIC as the IO APIC interrupts.

xen/xen_msi.h:
x86/xen/xen_msi.c:
- Introduce a Xen MSI implementation.

x86/xen/xen_nexus.c:
- Overwrite the default MSI hooks in the Xen Nexus to use the Xen MSI
implementation.

x86/xen/xen_pci.c:
- Introduce a Xen specific PCI bus that inherits from the ACPI PCI
bus and overwrites the native MSI methods.
- This is needed because when running under Xen the MSI messages used
to configure MSI interrupts on PCI devices are written by Xen
itself.

dev/acpica/acpi_pci.c:
- Lower the quality of the ACPI PCI bus so the newly introduced Xen
PCI bus can take over when needed.

conf/files.i386:
conf/files.amd64:
- Add the newly created files to the build process.

xen: add ACPI bus to xen_nexus when running as Dom0

Also disable a couple of ACPI devices that are not usable under Dom0.
To this end a couple of booleans are added that allow disabling ACPI
specific devices.

Sponsored by: Citrix Systems R&D
Reviewed by: jhb

x86/xen/xen_nexus.c:
- Return BUS_PROBE_SPECIFIC in the Xen Nexus attachement routine to
force the usage of the Xen Nexus.
- Attach the ACPI bus when running as Dom0.

dev/acpica/acpi_cpu.c:
dev/acpica/acpi_hpet.c:
dev/acpica/acpi_timer.c
- Add a variable that gates the addition of the devices.

x86/include/init.h:
- Declare variables that control the attachment of ACPI cpu, hpet and
timer devices.

xen: add a hook to perform AP startup

AP startup on PVH follows the PV method, so we need to add a hook in
order to diverge from bare metal.

Approved by: gibbs
Sponsored by: Citrix Systems R&D

amd64/amd64/machdep.c:
- Add hook for start_all_aps on native (using native_start_all_aps
defined in mp_machdep).

amd64/amd64/mp_machdep.c:
- Make some variables global because they will also be used by the
Xen PVH AP startup code.
- Use the start_all_aps hook to start APs.
- Rename start_all_aps to native_start_all_aps.

amd64/include/smp.h:
- Add declaration for native_start_all_aps.

x86/include/init.h:
- Declare start_all_aps hook in init_ops.

x86/xen/pv.c:
- Pick external declarations from mp_machdep.
- Introduce Xen PV code to start APs on PVH.
- Set start_all_aps init hook to use the Xen PVH implementation.

xen: add hook for AP bootstrap memory reservation

This hook will only be implemented for bare metal, Xen doesn't require
any bootstrap code since APs are started in long mode with paging
enabled.

Approved by: gibbs
Sponsored by: Citrix Systems R&D

amd64/amd64/machdep.c:
- Set mp_bootaddress hook for bare metal.

x86/include/init.h:
- Define mp_bootaddress in init_ops.

xen: implement hook to fetch and parse e820 memory map

e820 memory map is fetched using a hypercall under Xen PVH, so add a
hook to init_ops in oder to diverge from bare metal and implement a
Xen variant.

Approved by: gibbs
Sponsored by: Citrix Systems R&D

x86/include/init.h:
- Add a parse_memmap hook to init_ops, that will be called to fetch
and parse the memory map.

amd64/amd64/machdep.c:
- Decouple the fetch and the parse of the memmap, so the parse
function can be shared with Xen code.
- Move code around in order to implement the parse_memmap hook.

amd64/include/pc/bios.h:
- Declare bios_add_smap_entries (implemented in machdep.c).

x86/xen/pv.c:
- Implement fetching of e820 memmap when running as a PVH guest by
using the XENMEM_memory_map hypercall.

xen: implement an early timer for Xen PVH

When running as a PVH guest, there's no emulated i8254, so we need to
use the Xen PV timer as the early source for DELAY. This change allows
for different implementations of the early DELAY function and
implements a Xen variant for it.

Approved by: gibbs
Sponsored by: Citrix Systems R&D

dev/xen/timer/timer.c:
dev/xen/timer/timer.h:
- Implement Xen early delay functions using the PV timer and declare
them.

x86/include/init.h:
- Add hooks for early clock source initialization and early delay
functions.

i386/i386/machdep.c:
pc98/pc98/machdep.c:
amd64/amd64/machdep.c:
- Set early delay hooks to use the i8254 on bare metal.
- Use clock_init (that will in turn make use of init_ops) to
initialize the early clock source.

amd64/include/clock.h:
i386/include/clock.h:
- Declare i8254_delay and clock_init.

i386/xen/clock.c:
- Rename DELAY to i8254_delay.

x86/isa/clock.c:
- Introduce clock_init that will take care of initializing the early
clock by making use of the init_ops hooks.
- Move non ISA related delay functions to the newly introduced delay
file.

x86/x86/delay.c:
- Add moved delay related functions.
- Implement generic DELAY function that will use the init_ops hooks.

x86/xen/pv.c:
- Set PVH hooks for the early delay related functions in init_ops.

conf/files.amd64:
conf/files.i386:
conf/files.pc98:
- Add delay.c to the kernel build.

amd64: introduce hook for custom preload metadata parsers

Add hooks to amd64 in order to have diverging implementations, since
on Xen PV the metadata is passed to the kernel in a different form.

Approbed by: gibbs
Sponsored by: Citrix Systems R&D

amd64/amd64/machdep.c:
- Define init_ops for native.
- Put native code inside of native_parse_preload_data hook.
- Call the parse_preload_data in order to fill the metadata info.

x86/include/init.h:
- Declare the init_ops struct.

x86/xen/pv.c:
- Declare xen_init_ops that contains the Xen PV implementation of
init_ops.
- Implement the parse_preload_data for Xen PVH, the info is fetched
from HYPERVISOR_start_info->cmd_line as provided by Xen.