get_cr4
vmwrite(CR4_READ_SHADOW, get_cr4());
vmwrite(HOST_CR4, get_cr4());
GUEST_ASSERT(get_cr4() & X86_CR4_OSXSAVE);
: "D" (get_cr4())
set_cr4(get_cr4() | X86_CR4_PKE);
set_cr4(get_cr4() | X86_CR4_OSXSAVE);