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.

Discussed with:	grehan
Reviewed by:	grehan
Submitted by:	Tycho Nightingale (tycho.nightingale@pluribusnetworks.com)

M    share/examples/bhyve/vmrun.sh
AM   usr.sbin/bhyve/legacy_irq.c
AM   usr.sbin/bhyve/legacy_irq.h
M    usr.sbin/bhyve/Makefile
AM   usr.sbin/bhyve/uart_emul.c
M    usr.sbin/bhyve/bhyverun.c
AM   usr.sbin/bhyve/uart_emul.h
M    usr.sbin/bhyve/pci_uart.c
M    usr.sbin/bhyve/pci_emul.c
M    usr.sbin/bhyve/inout.c
M    usr.sbin/bhyve/pci_emul.h
M    usr.sbin/bhyve/inout.h
AM   usr.sbin/bhyve/pci_lpc.c
AM   usr.sbin/bhyve/pci_lpc.h

1 files changed, 13 insertions, 2 deletions

diff --git a/usr.sbin/bhyve/inout.c b/usr.sbin/bhyve/inout.c
index 29d9f17..a200265 100644
--- a/usr.sbin/bhyve/inout.c
+++ b/usr.sbin/bhyve/inout.c
@@ -84,7 +84,7 @@ register_default_iohandler(int start, int size)
 	iop.name = "default";
 	iop.port = start;
 	iop.size = size;
-	iop.flags = IOPORT_F_INOUT;
+	iop.flags = IOPORT_F_INOUT | IOPORT_F_DEFAULT;
 	iop.handler = default_inout;
 
 	register_inout(&iop);
@@ -159,7 +159,18 @@ register_inout(struct inout_port *iop)
 	int i;
 
 	VERIFY_IOPORT(iop->port, iop->size);
-	
+
+	/*
+	 * Verify that the new registration is not overwriting an already
+	 * allocated i/o range.
+	 */
+	if ((iop->flags & IOPORT_F_DEFAULT) == 0) {
+		for (i = iop->port; i < iop->port + iop->size; i++) {
+			if ((inout_handlers[i].flags & IOPORT_F_DEFAULT) == 0)
+				return (-1);
+		}
+	}
+
 	for (i = iop->port; i < iop->port + iop->size; i++) {
 		inout_handlers[i].name = iop->name;
 		inout_handlers[i].flags = iop->flags;