Commit 139bc8a6 authored by Marc Zyngier's avatar Marc Zyngier
Browse files

KVM: Forbid the use of tagged userspace addresses for memslots 



The use of a tagged address could be pretty confusing for the
whole memslot infrastructure as well as the MMU notifiers.

Forbid it altogether, as it never quite worked the first place.

Cc: stable@vger.kernel.org
Reported-by: default avatarRick Edgecombe <rick.p.edgecombe@intel.com>
Reviewed-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
parent 9529aaa0

Documentation/virt/kvm/api.rst

+3 −0
Original line number Diff line number Diff line
@@ -1269,6 +1269,9 @@ field userspace_addr, which must point at user addressable memory for 
the entire memory slot size.  Any object may back this memory, including

anonymous memory, ordinary files, and hugetlbfs.



On architectures that support a form of address tagging, userspace_addr must

be an untagged address.



It is recommended that the lower 21 bits of guest_phys_addr and userspace_addr

be identical.  This allows large pages in the guest to be backed by large

pages in the host.

virt/kvm/kvm_main.c

+1 −0
Original line number Diff line number Diff line
@@ -1290,6 +1290,7 @@ int __kvm_set_memory_region(struct kvm *kvm, 
		return -EINVAL;

	/* We can read the guest memory with __xxx_user() later on. */

	if ((mem->userspace_addr & (PAGE_SIZE - 1)) ||

	    (mem->userspace_addr != untagged_addr(mem->userspace_addr)) ||

	     !access_ok((void __user *)(unsigned long)mem->userspace_addr,

			mem->memory_size))

		return -EINVAL;