KVM: x86: hardware task switching support

This emulates the x86 hardware task switch mechanism in software, as it is
unsupported by either vmx or svm.  It allows operating systems which use it,
like freedos, to run as kvm guests.

Signed-off-by: Izik Eidus <izike@qumranet.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>

diff --cc arch/x86/kvm/svm.c
Simple merge

diff --cc arch/x86/kvm/svm.h
Simple merge

diff --cc arch/x86/kvm/tss.h
Simple merge

diff --cc arch/x86/kvm/vmx.c
Simple merge

diff --cc arch/x86/kvm/x86.c
Simple merge

diff --cc include/asm-x86/kvm_host.h
Simple merge