VMX: delay p2m insertion of APIC access page

VMX: delay p2m insertion of APIC access page

Inserting the mapping at domain creation time leads to a memory leak
when the creation fails later on and the domain uses separate CPU and
IOMMU page tables - the latter requires intermediate page tables to be
allocated, but there's no freeing of them at present in this case. Since
we don't need the p2m insertion to happen this early, avoid the problem
altogether by deferring it until the last possible point. This comes at
the price of not being able to handle an error other than by crashing
the domain.

Reported-by: Julien Grall <julien@xen.org>
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Release-Acked-by: Ian Jackson <iwj@xenproject.org>