bhyve: add qemu ppi emulation for tpm devices

[corvink]

Summary

Windows requires a physical presence interface to recognize the tpm
device. Qemu has an implementation for the ppi which can reuse. Using
the qemu ppi makes it very easy because we don't have to implement new
ppi functionality into ovmf. The qemu implementation is already there.

[markj]

usr.sbin/bhyve/tpm_ppi_qemu.c

117

These switch statements can be replaced by calls to memcpy().

134

Same comment everywhere else.

164

mr_name is unused. There is no need to use a stack buffer for a string which is known at compile time.

201

Same bug as elsewhere, mr.name must not be a pointer to a stack buffer. Please just use a string literal.

[corvink]

• use memcpy for mmio
• remove \n from warn calls
• add mmio registration helper

[corvink]

@jhb @markj Any additional comments?

[markj]

The warnx() strings do not need newlines.

usr.sbin/bhyve/tpm_ppi_qemu.c

100

If you make this a global variable, then this function isn't needed. Callers can call (un)register_mem() directly and we don't need the extra registration flag variable.