On 01/02/21 14:31, Marc Zyngier wrote:
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@xxxxxxxxxxxxxxx
Reported-by: Rick Edgecombe <rick.p.edgecombe@xxxxxxxxx>
Reviewed-by: Catalin Marinas <catalin.marinas@xxxxxxx>
Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
---
Documentation/virt/kvm/api.txt | 3 +++
virt/kvm/kvm_main.c | 1 +
2 files changed, 4 insertions(+)
diff --git a/Documentation/virt/kvm/api.txt b/Documentation/virt/kvm/api.txt
index a18e996fa54b..7064efd3b5ea 100644
--- a/Documentation/virt/kvm/api.txt
+++ b/Documentation/virt/kvm/api.txt
@@ -1132,6 +1132,9 @@ 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 8f3b40ec02b7..f25b5043cbca 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1017,6 +1017,7 @@ int __kvm_set_memory_region(struct kvm *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;
Indeed untagged_addr was added in 5.3.
Acked-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Paolo
