[Xen-changelog] [xen stable-4.6] x86emul: {L, S}{G, I}DT ignore operand size overrides in 64-bit mode

[patchbot@xxxxxxx]

commit 69baa97f3a60038729d348662f21ddf9dba3fe08
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Wed Jan 18 10:16:20 2017 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Wed Jan 18 10:16:20 2017 +0100

    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@xxxxxxxx>
    Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    master commit: 4ccb2adb96042e0d1e334c01fe260b32e6001db9
    master date: 2016-11-03 17:23:22 +0100
---
 xen/arch/x86/x86_emulate/x86_emulate.c | 17 +++++++++++------
 1 file changed, 11 insertions(+), 6 deletions(-)

diff --git a/xen/arch/x86/x86_emulate/x86_emulate.c 
b/xen/arch/x86/x86_emulate/x86_emulate.c
index 7d63240..5c085cf 100644
--- a/xen/arch/x86/x86_emulate/x86_emulate.c
+++ b/xen/arch/x86/x86_emulate/x86_emulate.c
@@ -3967,12 +3967,17 @@ 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 */
@@ -3989,7 +3994,7 @@ 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,
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.6

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