iommu/vt-d: Use cmpxchg16b to update posted format IRTE atomically
iommu/vt-d: Use cmpxchg16b to update posted format IRTE atomically

If IRTE is in posted format, the 'pda' field goes across the 64-bit
boundary, we need use cmpxchg16b to atomically update it. We only
expose posted-interrupt when X86_FEATURE_CX16 is supported and use
to update it atomically.

Signed-off-by: Feng Wu <521451f4bfda9a96135570722c9f0cfa4b647f81@intel.com>
Signed-off-by: Joerg Roedel <61aff96566804ea1da8a65de5bcc892ce07caceb@suse.de>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs