[RFC] Hypercalls from HVM guests

[Steve Ofsthun <sofsthun@virtualiron.com>]

Hi,

I am currently working on hypercalls from HVM guests.  I started with a set
of Intel patches posted to xen-devel last September.  I currently have code
running for both 32-bit and 64-bit HVM guests running on a 64-bit hypervisor.

I am curious why none of the original patches were accepted, and what I might
need to do to make them acceptable.

Is other work being done in this area that hasn't been submitted?

Should I submit my version of the modified patches as is?

The following list summarizes the changes.

Hypervisor changes:

o Add vmexit handling for the VMCALL instruction.  This includes adjustments
   to hypercall arguments due to 32-bit vs. 64-bit calling conventions.

o Modify copy_to_user/copy_from_user to use hvm_copy for HVM guests.

o Modify grant table setup to properly map the grant table shared data for
   hvm guests.

o Provide alternate headers for compiling 32-bit HVM guest code to interface
   with a 64-bit hypervisor.  Many of the hypervisor structures used for
   hypercalls vary between 32-bit and 64-bit guests.

Dom 0 changes:

o Modify HVM building to properly map in a xen start info page and the shared
   info page for event channel notifications.

o Add a virtual PCI device to QEMU to facilitate event channel handling.

Dom U (HVM) driver changes:

o Modify grant table setup for HVM guest code.

o Modify event channel handling to interface with an unmodified Linux kernel
   running as an HVM guest.

o Make misc xen support available as a loadable module.

Steve
-- 
Steve Ofsthun - Virtual Iron Software, Inc.