re: port-amd64/59860: nvmm: support AVX2, AVX512, &c.

[matthew green <mrg%eterna23.net@localhost>]

i seems to have gotten past that with a simple mask in vmx_init():

-	vmx_xcr0_mask = x86_xsave_features;
+	vmx_xcr0_mask = x86_xsave_features & __BITS(XSAVE_MAX_COMPONENT, 0);

not sure why, but my cpu ends up with XCR0_PKRU set here (i mean,
the cpu has it, but do we otherwise support it?)

it seems to work with that fix:

cpu0: xsave features 0x7<x87,SSE,AVX>

from the guest.  it seems to work:

# cd /usr/tests/kernel
# atf-run t_signal_and_fpu
....
tc-start: 1783901653.490927, xmm
tc-end: 1783901655.349492, xmm, passed
tc-start: 1783901655.350912, ymm
tc-end: 1783901657.349512, ymm, passed
tp-end: 1783901657.350932, t_signal_and_fpu
info: time.end, Mon Jul 13 00:14:17 UTC 2026


.mrg.