VMWRITE

if not in_vmx:
    fault(UD)
f = field.read()                 # the field's encoding
if vmx_nonroot:
    p = current_vmcs
    pri = vmcs_read(p, 0x4002)   # processor-based controls; bit
    sec = 0                      # 31 activates the secondary ones
    if pri >> 31:
        sec = vmcs_read(p, 0x401E)
    out = 1
    if sec >> 14 & 1 and not f >> 15:
        bm = vmcs_read(p, 0x2028)  # VMCS shadowing: the VMWRITE
        b = phys_read(bm | f >> 3, 8)  # bitmap, a bit a field
        out = b >> (f & 7) & 1
    if out:
        vm_exit(25)              # the hypervisor emulates it
if CPL > 0:
    fault(GP, 0)
p = current_vmcs
if vmx_nonroot:
    p = vmcs_read(current_vmcs, 0x2800)
if p == NO_VMCS:
    vm_fail_invalid()
else:
    v = src.read()               # a read of memory may fault here,
                                 # before the field is checked
    ro = not msr[IA32_VMX_MISC] >> 29 & 1
    if not vmcs_has(f):
        vm_fail(12)              # in a guest, the SDM does not say
                                 # which VMCS takes the number
    elif f >> 10 & 3 == 1 and ro:
        vm_fail(13)              # a VM-exit information field,
                                 # which only some processors let
                                 # software write
    else:
        vmcs_write(p, f, v)      # the field's bits: a shorter one
                                 # drops the rest of v
        vm_succeed()