From: Marc Zyngier maz@kernel.org
commit 139bc8a6146d92822c866cf2fd410159c56b3648 upstream.
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: Rick Edgecombe rick.p.edgecombe@intel.com Reviewed-by: Catalin Marinas catalin.marinas@arm.com Signed-off-by: Marc Zyngier maz@kernel.org Acked-by: Paolo Bonzini pbonzini@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- Documentation/virt/kvm/api.txt | 3 +++ virt/kvm/kvm_main.c | 1 + 2 files changed, 4 insertions(+)
--- a/Documentation/virt/kvm/api.txt +++ b/Documentation/virt/kvm/api.txt @@ -1132,6 +1132,9 @@ field userspace_addr, which must point a 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. --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -1017,6 +1017,7 @@ int __kvm_set_memory_region(struct kvm * /* We can read the guest memory with __xxx_user() later on. */ if ((id < KVM_USER_MEM_SLOTS) && ((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))) goto out;