bhyvectl/amd64: add --get-cpuid-cfg

[rosenfeld_grumpf.hope-2000.org]

Summary

Add a command to bhyvectl to fetch and print the CPUID configuration
for a VCPU. The CPUID entries, if any, are printed in hex and ASCII. No
pretty-printing of the information is performed.

[rosenfeld_grumpf.hope-2000.org]

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[markj]

usr.sbin/bhyvectl/amd64/bhyvectl_machdep.c

1927

Where exactly does it get filled in? This looks like it always queries vcpu 0, ignoring the --cpu parameter.

[rosenfeld_grumpf.hope-2000.org]

usr.sbin/bhyvectl/amd64/bhyvectl_machdep.c

1927

This is done in vcpu_ioctl() in vmmapi.c, called by vm_get_cpuid() in vmmapi_machdep.c:

int
vcpu_ioctl(struct vcpu *vcpu, u_long cmd, void *arg)
{
	/*
	 * XXX: fragile, handle with care
	 * Assumes that the first field of the ioctl data
	 * is the vcpuid.
	 */
	*(int *)arg = vcpu->vcpuid;
	return (ioctl(vcpu->ctx->fd, cmd, arg));
}

[markj]

usr.sbin/bhyvectl/amd64/bhyvectl_machdep.c

1927

Right, I forgot about that bit of magic. (I'd rather initialize vvcc_vcpuid = -1 in that case.)