FreeBSD enablement for ARM64 in Hyper-V: fixing hung issue during Hyper-V initialization

[schakrabarti_microsoft.com]

Summary

In non-Hyper-V systems during Hyper-V initialization, system initialization was getting hung, as hyperv_identify(),
was returning successful irrespective of the type of the platform.

Test Plan

The change has been tested on Hyper-V on ARM64, but needs to be tested on
non-Hyper-V arm and arm64 system to validate a successful boot.

[whu]

sys/conf/files.arm64

216 ↗

(On Diff #112421)

Can you fix the indentations on these lines?

sys/dev/hyperv/vmbus/aarch64/hyperv_aarch64.c

85

Can you add some comments on what this function does? And the return values mean?

105

This will set the ret to 0 if they match. The return value is the same as above cases when it cannot find or map the fadt. It doesn't seem right.

119

See comments above. It is not right.

[andrew]

This should be 4 commits, one for each file.

sys/dev/hyperv/vmbus/aarch64/hyperv_aarch64.c

92

This should probably be named is_hyperv or similar and return a bool. The current name looks like it returns the hyper-v ID when it's just checking it it is running under it.

124

No need for the else when the if returns.

[andrew]

sys/dev/hyperv/vmbus/aarch64/hyperv_aarch64.c

111–112

These two lines could just be:

return (strncmp((char *)&hypervid, "MsHyperV", 8) == 0);