[Xen-changelog] [xen master] x86emul: correct behavior for single iteration REP INS/OUTS

[patchbot@xxxxxxx]

commit 061cd0f0e5c41335150e0d234d8ad0aff7b6da11
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Thu Feb 2 12:48:59 2017 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Thu Feb 2 12:48:59 2017 +0100

    x86emul: correct behavior for single iteration REP INS/OUTS
    
    The initial operation done on these paths may raise an exception (for
    ->read_io() that's possible only on the PV path, when the I/O port
    access check has been deferred). We have to suppress put_rep_prefix()
    updating rCX in that case. From an abstract perspective this also
    applies to RETRY being returned.
    
    Reported-by: Wei Liu <wei.liu2@xxxxxxxxxx>
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Wei Liu <wei.liu2@xxxxxxxxxx>
    Tested-by: Wei Liu <wei.liu2@xxxxxxxxxx>
    Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
 xen/arch/x86/x86_emulate/x86_emulate.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/xen/arch/x86/x86_emulate/x86_emulate.c 
b/xen/arch/x86/x86_emulate/x86_emulate.c
index 21dd98c..dbda4b3 100644
--- a/xen/arch/x86/x86_emulate/x86_emulate.c
+++ b/xen/arch/x86/x86_emulate/x86_emulate.c
@@ -3134,7 +3134,7 @@ x86_emulate(
         if ( nr_reps == 1 && ops->read_io && ops->write )
         {
             rc = ops->read_io(port, dst.bytes, &dst.val, ctxt);
-            if ( rc == X86EMUL_OKAY )
+            if ( rc != X86EMUL_UNHANDLEABLE )
                 nr_reps = 0;
         }
         if ( (nr_reps > 1 || rc == X86EMUL_UNHANDLEABLE) && ops->rep_ins )
@@ -3175,7 +3175,7 @@ x86_emulate(
         {
             rc = read_ulong(ea.mem.seg, ea.mem.off, &dst.val, dst.bytes,
                             ctxt, ops);
-            if ( rc == X86EMUL_OKAY )
+            if ( rc != X86EMUL_UNHANDLEABLE )
                 nr_reps = 0;
         }
         if ( (nr_reps > 1 || rc == X86EMUL_UNHANDLEABLE) && ops->rep_outs )
--
generated by git-patchbot for /home/xen/git/xen.git#master

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