arm/arm64: KVM: Ensure memslots are within KVM_PHYS_SIZE

arm/arm64: KVM: Ensure memslots are within KVM_PHYS_SIZE

commit c3058d5da2222629bc2223c488a4512b59bb4baf upstream.

[Since we don't backport commit 8eef912 (arm/arm64: KVM: map MMIO regions
at creation time) for linux-3.14.y, the context of this patch is
different, while the change itself is same.]

When creating or moving a memslot, make sure the IPA space is within the
addressable range of the guest.  Otherwise, user space can create too
large a memslot and KVM would try to access potentially unallocated page
table entries when inserting entries in the Stage-2 page tables.

Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Shannon Zhao <shannon.zhao@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>