Virtualization - May 2013 - Possible bug in KVM arch/x86/kvm/emulate.c:check_cr_write()?

Hi,

When KVM's check_cr_write() is invoked to write to %cr3, it tests that
the lower three bits of %cr3 are set to zero. On real h/w (tested on
Core2, K10), these bits are ignored; the AMD64 documentation describes
the bits as 'should', but not 'must' be zero. The Intel
documentation
seems to indicate that the bits are ignored as well.

I don't know whether to call this a bug or not, but it is a divergence
from real h/w.

Thanks,
-- vs;