x86/hvm: add vcpu parameter to guest memory copy function

x86/hvm: add vcpu parameter to guest memory copy function

Current __hvm_copy assumes that the destination memory belongs to the current
vcpu, but this is not always the case since for PVHv2 Dom0 build hvm copy
functions are used with current being the idle vcpu. Add a new vcpu parameter
to hvm copy in order to solve that. Note that only hvm_copy_to_guest_phys is
changed to take a vcpu parameter, because that's the only one at the moment
that's required in order to build a PVHv2 Dom0.

While there, also assert that the passed vcpu belongs to a HVM guest.

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Fix the build, retaining prior log message attributes.

Signed-off-by: Jan Beulich <jbeulich@suse.com>