[Xen-changelog] [xen stable-4.12] x86emul: 16-bit XBEGIN does not truncate rIP

[patchbot@xxxxxxx]

commit 88d4e37075d9f868ab05664d3fd918aedce37ecd
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Mon Nov 25 16:01:46 2019 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Mon Nov 25 16:01:46 2019 +0100

    x86emul: 16-bit XBEGIN does not truncate rIP
    
    SDM rev 071 points out this fact explicitly.
    
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    master commit: a72c508656c0a0fa573890b290064e6035971f86
    master date: 2019-11-15 14:15:31 +0100
---
 xen/arch/x86/x86_emulate/x86_emulate.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/xen/arch/x86/x86_emulate/x86_emulate.c 
b/xen/arch/x86/x86_emulate/x86_emulate.c
index 1c8fc712d1..225931f5ac 100644
--- a/xen/arch/x86/x86_emulate/x86_emulate.c
+++ b/xen/arch/x86/x86_emulate/x86_emulate.c
@@ -4072,10 +4072,12 @@ x86_emulate(
         {
             /*
              * xbegin unconditionally aborts, xabort is unconditionally
-             * a nop.
+             * a nop. It also does not truncate the destination address to
+             * 16 bits when 16-bit operand size is in effect.
              */
             if ( b & 1 )
             {
+                op_bytes = 4;
                 jmp_rel((int32_t)src.val);
                 _regs.r(ax) = 0;
             }
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.12

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