HYBRID: PV in HVM container

[Mukesh Rathor <mukesh.rathor@oracle.com>]

Hi guys,

Cheers!! I got PV in HVM container prototype working with single VCPU
(pinned to a cpu). Basically, I create a VMX container just like for
HVM guest (with some differences that I'll share soon when I clean up
the code). The PV guest starts in Protected mode with the usual
entry point startup_xen().

0. Guest kernel runs in ring 0, CS:0x10.

1. I use xen for all pt management just like a PV guest. So at present
   all faults are going to xen, and when fixup_page_fault() fails, they
   are injected into the container for the guest to handle it.

2. The guest manages the GDT, LDT, TR, in the container.

3. The guest installs the trap table in the vmx container instead of 
   do_set_trap_table(). 

4. Events/INTs are delivered via HVMIRQ_callback_vector.

5. MSR_GS_BASE is managed by the guest in the container itself.

6. Currently, I'm managing cr4 in the container, but going to xen
   for cr0. I need to revisit that.

7. Currently, VPID is disabled, I need to figure it out, and revisit.

8. Currently, VM_ENTRY_LOAD_GUEST_PAT is disabled, I need to look at 
   that. 

These are the salient points I can think of at the moment. Next, I am 
going to run LMBench and figure out the gains. After that, make sure
SMP works, and things are stable, and look at any enhancements. I need
to look at couple unrelated bugs at the moment, but hope to return back 
to this very soon.

thanks,
Mukesh