Re: [PATCH][v2] Hybrid extension support in Xen

[Paul Durrant <paul.durrant@citrix.com>]

Sheng Yang wrote:
> 
> 1. Enable SMP support through VCPU_OP in arch_set_info_guest().
> 2. A new hypercall in hvm_ops to enable hybrid.
> 3. Mapping IRQ to VIRQ when deliver to the guest.
> 4. Inject a guest defined vector to deliver notification for events.
> 5. Use CPUID leaf 0x40000002 to support hybrid feature
> 6. Reserve some space at the end of MMIO hole for grant table use.
> 
> Please review. Thanks!
> 

Why a complete new hypercall table; could you not just use the existing 
HVM table and add the extra hypercalls in?
Doing it this way would negate the need for the concept of a 'hybrid' 
HVM guest would it not? HVM guests that were aware of the hybrid 
extensions would use them, those that were unaware would not.

Also, why the extra E820 space for the grant table? You don't need the 
table that early so could you not just use fake PCI BAR space or 
somesuch and do the XENMEM_add_to_physmap hypercall to add 
XENMAPSPACE_grant_table later on?

   Paul

-- 
===============================
Paul Durrant, Software Engineer

Citrix Systems (R&D) Ltd.
First Floor, Building 101
Cambridge Science Park
Milton Road
Cambridge CB4 0FY
United Kingdom
===============================