vmm/amd64: port illumos cpuid control

[rosenfeld_grumpf.hope-2000.org]

Summary

This is a faithful port of two bhyve improvements coming from illumos:

• 14485 bhyve needs better cpuid control https://www.illumos.org/issues/14485 This adds vmm kernel support for overriding the CPUID information for a guest.
• 16223 bhyve returns bogus cpuid 8000_001D leaf https://www.illumos.org/issues/16223 This fixes an issue in 14485 discovered on AMD CPUs.

This does not include the bhyve tests added with illumos#14485 since
FreeBSD lacks the bhyve test suite. This does also not contain any
libvmmapi/bhyve userspace code to make this feature actually useful.

[corvink]

sys/amd64/include/vmm.h

808

826

sys/amd64/vmm/vmm_cpuid.c

28

This shouldn't be required anymore.

572

This could be split into a separate commit to make it easier to review and merge earlier if you like to.

sys/amd64/vmm/vmm_dev_machdep.c

504–521

That's checked by vm_set_cpuid too. I would prefer checking this stuff once.

[emaste]

sys/amd64/vmm/vmm_cpuid.c

2

572

In general if this is a bug fix or otherwise an improvement that can stand alone I would indeed do it in a separate commit (that may be MFC'd to stable branches independent of or earlier than the full new functionality).