diff options
authorMarc Zyngier <>2021-01-21 12:08:15 +0000
committerMarc Zyngier <>2021-01-21 14:17:36 +0000
commit139bc8a6146d92822c866cf2fd410159c56b3648 (patch)
parent9529aaa056edc76b3a41df616c71117ebe11e049 (diff)
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: Reported-by: Rick Edgecombe <> Reviewed-by: Catalin Marinas <> Signed-off-by: Marc Zyngier <>
2 files changed, 4 insertions, 0 deletions
diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
index 4e5316ed10e9..c347b7083abf 100644
--- a/Documentation/virt/kvm/api.rst
+++ b/Documentation/virt/kvm/api.rst
@@ -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.
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 2541a17ff1c4..a9abaf5f8e53 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -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,
return -EINVAL;