tree e481e08a2f3a7f517ad53e3ed8726438bf3e7939
parent 7c1c96ffb658fbfe66c5ebed6bcb5909837bc267
author Maxim Levitsky <mlevitsk@redhat.com> 1626699900 +0300
committer Greg Kroah-Hartman <gregkh@linuxfoundation.org> 1629269824 +0200

KVM: nSVM: always intercept VMLOAD/VMSAVE when nested (CVE-2021-3656)

commit c7dfa4009965a9b2d7b329ee970eb8da0d32f0bc upstream.

If L1 disables VMLOAD/VMSAVE intercepts, and doesn't enable
Virtual VMLOAD/VMSAVE (currently not supported for the nested hypervisor),
then VMLOAD/VMSAVE must operate on the L1 physical memory, which is only
possible by making L0 intercept these instructions.

Failure to do so allowed the nested guest to run VMLOAD/VMSAVE unintercepted,
and thus read/write portions of the host physical memory.

Fixes: 89c8a4984fc9 ("KVM: SVM: Enable Virtual VMLOAD VMSAVE feature")

Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>