Xen is doing this [1] and currently triggers an abort.
[1] http://xenbits.xenproject.org/gitweb/?p=xen.git;a=blob;f=xen/drivers/passthrough/vtd/iommu.c;h=
daaed0abbdd06b6ba3d948ea103aadf02651e83c;hb=refs/heads/master#l1108
Reported-by: Luis Lloret <luis_lloret@mentor.com>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
/* Fault Event Address Register, 32-bit */
case DMAR_FEADDR_REG:
- assert(size == 4);
- vtd_set_long(s, addr, val);
+ if (size == 4) {
+ vtd_set_long(s, addr, val);
+ } else {
+ /*
+ * While the register is 32-bit only, some guests (Xen...) write to
+ * it with 64-bit.
+ */
+ vtd_set_quad(s, addr, val);
+ }
break;
/* Fault Event Upper Address Register, 32-bit */