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KVM: Forbid the use of tagged userspace addresses for memslots

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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>
This commit is contained in:
Marc Zyngier 2021-01-21 12:08:15 +00:00
parent 9529aaa056
commit 139bc8a614
2 changed files with 4 additions and 0 deletions
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3
Documentation/virt/kvm/api.rst
View File

@ -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.

1
virt/kvm/kvm_main.c
View File

@ -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;