tree 8b941c7e959fab7a677df0d6d7c4052ec468342d
parent 36be0b9deb23161e9eba962c215aece551113a15
author Paolo Bonzini <pbonzini@redhat.com> 1394057992 +0100
committer Paolo Bonzini <pbonzini@redhat.com> 1395055299 +0100

KVM: x86: handle missing MPX in nested virtualization

When doing nested virtualization, we may be able to read BNDCFGS but
still not be allowed to write to GUEST_BNDCFGS in the VMCS.  Guard
writes to the field with vmx_mpx_supported(), and similarly hide the
MSR from userspace if the processor does not support the field.

We could work around this with the generic MSR save/load machinery,
but there is only a limited number of MSR save/load slots and it is
not really worthwhile to waste one for a scenario that should not
happen except in the nested virtualization case.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>