File 581b647a-x86emul-L-S-G-I-DT-ignore-opsz-overrides-in-64-bit-mode.patch of Package xen.4216

# Commit 4ccb2adb96042e0d1e334c01fe260b32e6001db9
# Date 2016-11-03 17:23:22 +0100
# Author Jan Beulich <jbeulich@suse.com>
# Committer Jan Beulich <jbeulich@suse.com>
x86emul: {L,S}{G,I}DT ignore operand size overrides in 64-bit mode

This affects not only the layout of the data (always 2+8 bytes), but
also the contents (no truncation to 24 bits occurs).

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>

--- a/xen/arch/x86/x86_emulate/x86_emulate.c
+++ b/xen/arch/x86/x86_emulate/x86_emulate.c
@@ -3986,12 +3986,17 @@ x86_emulate(
                                          x86_seg_idtr : x86_seg_gdtr,
                                          &reg, ctxt)) )
                 goto done;
-            if ( op_bytes == 2 )
+            if ( mode_64bit() )
+                op_bytes = 8;
+            else if ( op_bytes == 2 )
+            {
                 reg.base &= 0xffffff;
-            if ( (rc = ops->write(ea.mem.seg, ea.mem.off+0,
-                                  &reg.limit, 2, ctxt)) ||
-                 (rc = ops->write(ea.mem.seg, ea.mem.off+2,
-                                  &reg.base, mode_64bit() ? 8 : 4, ctxt)) )
+                op_bytes = 4;
+            }
+            if ( (rc = ops->write(ea.mem.seg, ea.mem.off, &reg.limit,
+                                  2, ctxt)) != X86EMUL_OKAY ||
+                 (rc = ops->write(ea.mem.seg, ea.mem.off + 2, &reg.base,
+                                  op_bytes, ctxt)) != X86EMUL_OKAY )
                 goto done;
             break;
         case 2: /* lgdt */
@@ -4008,7 +4013,7 @@ x86_emulate(
             generate_exception_if(!is_canonical_address(base), EXC_GP, 0);
             reg.base = base;
             reg.limit = limit;
-            if ( op_bytes == 2 )
+            if ( !mode_64bit() && op_bytes == 2 )
                 reg.base &= 0xffffff;
             if ( (rc = ops->write_segment((modrm_reg & 1) ?
                                           x86_seg_idtr : x86_seg_gdtr,