[x86] Virtualize EFLAGS.IF and handle physical interrupts.

o Do a VMEXIT on physical interrupt.
o Virtualize EFLAGS.IF so that non-maskable interrupts
  are not held by guests.

Signed-off-by: Himanshu Chauhan <hschauhan@nulltrace.org>
[emulators] Minor beautification change in MC416818 emulator.

Signed-off-by: Himanshu Chauhan <hschauhan@nulltrace.org>
[EMULATORS] i8259 PIC Emulator

This is first cut implemenation of i8259a compatible PIC
emulator.

Signed-off-by: Himanshu Chauhan <hschauhan@nulltrace.org>
[x86] Enable and Use i8259a PIC emulator for guest.

This patch enables the i8259a compatible PIC emulator. All required
wiring is added.

Signed-off-by: Himanshu Chauhan <hschauhan@nulltrace.org>
[x86] Handle VM Exit in exception like ARM

Xvisor by design handles VM EXIT as part of exception.
It assumes that VM EXIT causes an exception. To fit
in that world, we use the software interrupt method
to induce a fake exception. Complete VM EXIT is
handled while in that exception handler.

Signed-off-by: Himanshu Chauhan <hschauhan@nulltrace.org>
[EMULATORS] Add Legacy Intel 8254 PIT

Add Intel's 8254/8253 compatilbe programmable interrupt
timer.

Signed-off-by: Himanshu Chauhan <hschauhan@nulltrace.org>
[x86] Enable i8254 PIT for x86 Guests.

Signed-off-by: Himanshu Chauhan <hschauhan@nulltrace.org>
[x86] Beautification changes in VCPU regdump

Signed-off-by: Himanshu Chauhan <hschauhan@nulltrace.org>
[x86] Various beautification changes in x86

o Move a lot of prints from verbose to debug.
o Made the vcpu dump state pretty.

Signed-off-by: Himanshu Chauhan <hschauhan@nulltrace.org>
[x86] Dump guest VCPU regs from VMCB when saved by hardware.

Signed-off-by: Himanshu Chauhan <hschauhan@nulltrace.org>