x86emul: tell cmpxchg hook whether LOCK is in effect

This is necessary for the hook to correctly perform the operation.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Paul Durrant <paul.durrant@citrix.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Tim Deegan <tim@xen.org>

tools/fuzz/x86_instruction_emulator/fuzz-emul.c

@@ -347,6 +347,7 @@ static int fuzz_cmpxchg(
     void *old,
     void *new,
     unsigned int bytes,
+    bool lock,
     struct x86_emulate_ctxt *ctxt)
 {
     /*

tools/tests/x86_emulator/test_x86_emulator.c

@@ -320,6 +320,7 @@ static int cmpxchg(
     void *old,
     void *new,
     unsigned int bytes,
+    bool lock,
     struct x86_emulate_ctxt *ctxt)
 {
     if ( verbose )

xen/arch/x86/hvm/emulate.c

@@ -1250,6 +1250,7 @@ static int hvmemul_cmpxchg_discard(
     void *p_old,
     void *p_new,
     unsigned int bytes,
+    bool lock,
     struct x86_emulate_ctxt *ctxt)
 {
     return X86EMUL_OKAY;
@@ -1293,6 +1294,7 @@ static int hvmemul_cmpxchg(
     void *p_old,
     void *p_new,
     unsigned int bytes,
+    bool lock,
     struct x86_emulate_ctxt *ctxt)
 {
     /* Fix this in case the guest is really relying on r-m-w atomicity. */

xen/arch/x86/mm/shadow/common.c

@@ -281,6 +281,7 @@ hvm_emulate_cmpxchg(enum x86_segment seg,
                     void *p_old,
                     void *p_new,
                     unsigned int bytes,
+                    bool lock,
                     struct x86_emulate_ctxt *ctxt)
 {
     struct sh_emulate_ctxt *sh_ctxt =

xen/arch/x86/pv/ro-page-fault.c

@@ -216,7 +216,7 @@ static int ptwr_emulated_write(enum x86_segment seg, unsigned long offset,
 
 static int ptwr_emulated_cmpxchg(enum x86_segment seg, unsigned long offset,
                                  void *p_old, void *p_new, unsigned int bytes,
-                                 struct x86_emulate_ctxt *ctxt)
+                                 bool lock, struct x86_emulate_ctxt *ctxt)
 {
     intpte_t old = 0, new = 0;
 

xen/arch/x86/x86_emulate/x86_emulate.c

@@ -1947,7 +1947,7 @@ protmode_load_seg(
 
         fail_if(!ops->cmpxchg);
         switch ( (rc = ops->cmpxchg(sel_seg, (sel & 0xfff8) + 4, &desc.b,
-                                    &new_desc_b, sizeof(desc.b), ctxt)) )
+                                    &new_desc_b, sizeof(desc.b), true, ctxt)) )
         {
         case X86EMUL_OKAY:
             break;
@@ -6941,7 +6941,8 @@ x86_emulate(
             }
 
             if ( (rc = ops->cmpxchg(ea.mem.seg, ea.mem.off, old, aux,
-                                    op_bytes, ctxt)) != X86EMUL_OKAY )
+                                    op_bytes, lock_prefix,
+                                    ctxt)) != X86EMUL_OKAY )
                 goto done;
             _regs.eflags |= X86_EFLAGS_ZF;
         }
@@ -8392,7 +8393,7 @@ x86_emulate(
             fail_if(!ops->cmpxchg);
             rc = ops->cmpxchg(
                 dst.mem.seg, dst.mem.off, &dst.orig_val,
-                &dst.val, dst.bytes, ctxt);
+                &dst.val, dst.bytes, true, ctxt);
         }
         else
         {

xen/arch/x86/x86_emulate/x86_emulate.h

@@ -245,10 +245,11 @@ struct x86_emulate_ops
         struct x86_emulate_ctxt *ctxt);
 
     /*
-     * cmpxchg: Emulate an atomic (LOCKed) CMPXCHG operation.
+     * cmpxchg: Emulate a CMPXCHG operation.
      *  @p_old: [IN ] Pointer to value expected to be current at @addr.
      *  @p_new: [IN ] Pointer to value to write to @addr.
      *  @bytes: [IN ] Operation size (up to 8 (x86/32) or 16 (x86/64) bytes).
+     *  @lock:  [IN ] atomic (LOCKed) operation
      */
     int (*cmpxchg)(
         enum x86_segment seg,
@@ -256,6 +257,7 @@ struct x86_emulate_ops
         void *p_old,
         void *p_new,
         unsigned int bytes,
+        bool lock,
         struct x86_emulate_ctxt *ctxt);
 
     /*