xen/arm: Correctly handle non-page aligned pointer in raw_copy_from_guest

The current implementation of raw_copy_guest helper may lead to data corruption
and sometimes Xen crash when the guest virtual address is not aligned to
PAGE_SIZE.

When the total length is higher than a page, the length to read is badly
compute with
    min(len, (unsigned)(PAGE_SIZE - offset))

As the offset is only computed one time per function, if the start address was
not aligned to PAGE_SIZE, we can end up in same iteration:
    - to read accross page boundary => xen crash
    - read the previous page => data corruption

This issue can be resolved by setting offset to 0 at the end of the first
iteration. Indeed, after it, the virtual guest address is always aligned
to PAGE_SIZE.

Signed-off-by: Julien Grall <julien.grall@linaro.org>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Cc: George Dunlap <george.dunlap@citrix.com>
[ ijc -- duplicated the comment in the other two functions with this behaviour ]
xen/arm: Save/restore GICH_VMCR on domain context switch

GICH_VMCR register contains alias to important bits of GICV interface such as:
    - priority mask of the CPU
    - EOImode
    - ...

We were safe because Linux guest always use the same value for this bits.
When new guests will handle priority or change EOI mode, VCPU interrupt
management will be in a wrong state.

Signed-off-by: Julien Grall <julien.grall@linaro.org>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Cc: George Dunlap <george.dunlap@citrix.com>
libxl: Properly declare libxlu_disk_l.h in AUTOINCS

This is necessary so that make doesn't do things which depend on this
file until flex has finished producing it.

Reported-by: Olaf Hering <olaf@aepfle.de>
Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
CC: Ian Campbell <Ian.Campbell@citrix.com>
CC: Olaf Hering <olaf@aepfle.de>
Tested-by: Olaf Hering <olaf@aepfle.de>
CC: George Dunlap <george.dunlap@eu.citrix.com>
Acked-by: Ian Campbell <Ian.Campbell@citrix.com>