intel_iommu: Set default aw_bits to 48 starting from QEMU 9.2

According to VTD spec, stage-1 page table could support 4-level and
5-level paging.

However, 5-level paging translation emulation is unsupported yet.
That means the only supported value for aw_bits is 48. So default
aw_bits to 48 when stage-1 translation is turned on.

For legacy and scalable modes, 48 is the default choice for modern
OS when both 48 and 39 are supported. So it makes sense to set
default to 48 for these two modes too starting from QEMU 9.2.
Use pc_compat_9_1 to handle the compatibility for machines before
9.2.

Suggested-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Reviewed-by: Clément Mathieu--Drif<clement.mathieu--drif@eviden.com>
Reviewed-by: Yi Liu <yi.l.liu@intel.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Message-Id: <20241212083757.605022-17-zhenzhong.duan@intel.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

0 files changed, 0 insertions, 0 deletions