KVM: nVMX: fix EPT permissions as reported in exit qualification

KVM: nVMX: fix EPT permissions as reported in exit qualification

commit 0780516a18f87e881e42ed815f189279b0a1743c upstream.

This fixes the new ept_access_test_read_only and ept_access_test_read_write
testcases from vmx.flat.

The problem is that gpte_access moves bits around to switch from EPT
bit order (XWR) to ACC_*_MASK bit order (RWX).  This results in an
incorrect exit qualification.  To fix this, make pt_access and
pte_access operate on raw PTE values (only with NX flipped to mean
"can execute") and call gpte_access at the end of the walk.  This
lets us use pte_access to compute the exit qualification with XWR
bit order.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Xiao Guangrong <xiaoguangrong@tencent.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
[bwh: Backported to 4.9:
 - There's no support for EPT accessed/dirty bits, so do not use
   have_ad flag
 - Adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>