bhyve: protect MMIO mapped BDSM register

[corvink]

Summary

The Windows graphics driver reads the value of the BDSM register from MMIO
space. This value makes no sense in our virtual environment because it's a host
address. Therefore, we have to trap and emulate it.

[corvink]

• rebase onto main

[markj]

usr.sbin/bhyve/amd64/pci_gvt-d.c

67

The indentation of the case labels should be the same as the indentation of switch. .clang-format has IndentCaseLabels: false for this.

91

Is it correct that the offset is the same for both writes?

[corvink]

• fix style issue
• use correct offset for 64 bit BDSM read/writes

[corvink]

• use uint64_t instead of vm_* types
• account for new handler interface (including baridx)

[jhb]

usr.sbin/bhyve/amd64/pci_gvt-d.c

126

Maybe add a #define for this magic number to document it a bit more?