MFC r267921, r267934, r267949, r267959, r267966, r268202, r268276,
r268427, r268428, r268521, r268638, r268639, r268701, r268777,
r268889, r268922, r269008, r269042, r269043, r269080, r269094,
r269108, r269109, r269281, r269317, r269700, r269896, r269962,
r269989.

Catch bhyve up to CURRENT.

Lightly tested with FreeBSD i386/amd64, Linux i386/amd64, and
OpenBSD/amd64. Still resolving an issue with OpenBSD/i386.

Many thanks to jhb@ for all the hard work on the prior MFCs !

r267921 - support the "mov r/m8, imm8" instruction
r267934 - document options
r267949 - set DMI vers/date to fixed values
r267959 - doc: sort cmd flags
r267966 - EPT misconf post-mortem info
r268202 - use correct flag for event index
r268276 - 64-bit virtio capability api
r268427 - invalidate guest TLB when cr3 is updated, needed for TSS
r268428 - identify vcpu's operating mode
r268521 - use correct offset in guest logical-to-linear translation
r268638 - chs value
r268639 - chs fake values
r268701 - instr emul operand/address size override prefix support
r268777 - emulation for legacy x86 task switching
r268889 - nested exception support
r268922 - fix INVARIANTS build
r269008 - emulate instructions found in the OpenBSD/i386 5.5 kernel
r269042 - fix fault injection
r269043 - Reduce VMEXIT_RESTARTs in task_switch.c
r269080 - fix issues in PUSH emulation
r269094 - simplify return values from the inout handlers
r269108 - don't return -1 from the push emulation handler
r269109 - avoid permanent sleep in vm_handle_hlt()
r269281 - list VT-x features in base kernel dmesg
r269317 - Mark AHCI fatal errors as not completed
r269700 - Support PCI extended config space in bhyve
r269896 - Minor cleanup
r269962 - use max guest memory when creating IOMMU domain
r269989 - fix interrupt mode names

MFC 266424,266476,266524,266573,266595,266626,266627,266633,266641,266642,
266708,266724,266934,266935,268521:
Emulation of the "ins" and "outs" instructions.

Various fixes for translating guest linear addresses to guest physical
addresses.

MFC 259826,259997,259998:
Support soft power-off via the ACPI S5 state for bhyve guests and wire
up a virtual power button to SIGTERM:
- Implement the PM1_EVT and PM1_CTL registers required by ACPI.
- Emulate the Reset Control register at I/O port 0xcf9.
- Advertise an _S5 package.
- Implement an SMI_CMD register with commands to enable and disable ACPI.
Currently the only change when ACPI is enabled is to enable the virtual
power button via SIGTERM.
- Implement a fixed-feature power button when ACPI is enabled by asserting
PWRBTN_STS in PM1_EVT when SIGTERM is received.
- Add support for EVFILT_SIGNAL events to mevent.
- Implement support for the ACPI system command interrupt (SCI) and assert
it when needed based on the values in PM1_EVT. Mark the SCI as active-low
and level triggered in the MADT and MP Table.

MFC r257293.

Add support for PCI-to-ISA LPC bridge emulation. If the LPC bus is attached
to a virtual machine then we implicitly create COM1 and COM2 ISA devices.

Prior to this change the only way of attaching a COM port to the virtual
machine was by presenting it as a PCI device that is mapped at the legacy
I/O address 0x3F8 or 0x2F8.

There were some issues with the original approach:
- It did not work at all with UEFI because UEFI will reprogram the PCI device
BARs and remap the COM1/COM2 ports at non-legacy addresses.
- OpenBSD GENERIC kernel does not create a /dev/console because it expects
the uart device at the legacy 0x3F8/0x2F8 address to be an ISA device.
- It was functional with a FreeBSD guest but caused the console to appear
on /dev/ttyu2 which was not intuitive.

The uart emulation is now independent of the bus on which it resides. Thus it
is possible to have uart devices on the PCI bus in addition to the legacy
COM1/COM2 devices behind the LPC bus.

The command line option to attach ISA COM1/COM2 ports to a virtual machine is
"-s <bus>,lpc -l com1,stdio".

The command line option to create a PCI-attached uart device is:
"-s <bus>,uart[,stdio]"

The command line option to create PCI-attached COM1/COM2 device is:
"-S <bus>,uart[,stdio]". This style of creating COM ports is deprecated.

Approved by: re (glebius)

MFC r267921, r267934, r267949, r267959, r267966, r268202, r268276,
r268427, r268428, r268521, r268638, r268639, r268701, r268777,
r268889, r268922, r269008, r269042, r269043, r269080, r269094,
r269108, r269109, r269281, r269317, r269700, r269896, r269962,
r269989.

Catch bhyve up to CURRENT.

Lightly tested with FreeBSD i386/amd64, Linux i386/amd64, and
OpenBSD/amd64. Still resolving an issue with OpenBSD/i386.

Many thanks to jhb@ for all the hard work on the prior MFCs !

r267921 - support the "mov r/m8, imm8" instruction
r267934 - document options
r267949 - set DMI vers/date to fixed values
r267959 - doc: sort cmd flags
r267966 - EPT misconf post-mortem info
r268202 - use correct flag for event index
r268276 - 64-bit virtio capability api
r268427 - invalidate guest TLB when cr3 is updated, needed for TSS
r268428 - identify vcpu's operating mode
r268521 - use correct offset in guest logical-to-linear translation
r268638 - chs value
r268639 - chs fake values
r268701 - instr emul operand/address size override prefix support
r268777 - emulation for legacy x86 task switching
r268889 - nested exception support
r268922 - fix INVARIANTS build
r269008 - emulate instructions found in the OpenBSD/i386 5.5 kernel
r269042 - fix fault injection
r269043 - Reduce VMEXIT_RESTARTs in task_switch.c
r269080 - fix issues in PUSH emulation
r269094 - simplify return values from the inout handlers
r269108 - don't return -1 from the push emulation handler
r269109 - avoid permanent sleep in vm_handle_hlt()
r269281 - list VT-x features in base kernel dmesg
r269317 - Mark AHCI fatal errors as not completed
r269700 - Support PCI extended config space in bhyve
r269896 - Minor cleanup
r269962 - use max guest memory when creating IOMMU domain
r269989 - fix interrupt mode names

MFC 266424,266476,266524,266573,266595,266626,266627,266633,266641,266642,
266708,266724,266934,266935,268521:
Emulation of the "ins" and "outs" instructions.

Various fixes for translating guest linear addresses to guest physical
addresses.

MFC 259826,259997,259998:
Support soft power-off via the ACPI S5 state for bhyve guests and wire
up a virtual power button to SIGTERM:
- Implement the PM1_EVT and PM1_CTL registers required by ACPI.
- Emulate the Reset Control register at I/O port 0xcf9.
- Advertise an _S5 package.
- Implement an SMI_CMD register with commands to enable and disable ACPI.
Currently the only change when ACPI is enabled is to enable the virtual
power button via SIGTERM.
- Implement a fixed-feature power button when ACPI is enabled by asserting
PWRBTN_STS in PM1_EVT when SIGTERM is received.
- Add support for EVFILT_SIGNAL events to mevent.
- Implement support for the ACPI system command interrupt (SCI) and assert
it when needed based on the values in PM1_EVT. Mark the SCI as active-low
and level triggered in the MADT and MP Table.

MFC r257293.

Add support for PCI-to-ISA LPC bridge emulation. If the LPC bus is attached
to a virtual machine then we implicitly create COM1 and COM2 ISA devices.

Prior to this change the only way of attaching a COM port to the virtual
machine was by presenting it as a PCI device that is mapped at the legacy
I/O address 0x3F8 or 0x2F8.

There were some issues with the original approach:
- It did not work at all with UEFI because UEFI will reprogram the PCI device
BARs and remap the COM1/COM2 ports at non-legacy addresses.
- OpenBSD GENERIC kernel does not create a /dev/console because it expects
the uart device at the legacy 0x3F8/0x2F8 address to be an ISA device.
- It was functional with a FreeBSD guest but caused the console to appear
on /dev/ttyu2 which was not intuitive.

The uart emulation is now independent of the bus on which it resides. Thus it
is possible to have uart devices on the PCI bus in addition to the legacy
COM1/COM2 devices behind the LPC bus.

The command line option to attach ISA COM1/COM2 ports to a virtual machine is
"-s <bus>,lpc -l com1,stdio".

The command line option to create a PCI-attached uart device is:
"-s <bus>,uart[,stdio]"

The command line option to create PCI-attached COM1/COM2 device is:
"-S <bus>,uart[,stdio]". This style of creating COM ports is deprecated.

Approved by: re (glebius)