[PATCH 5/9] x86emul: re-use new stub_exn field in state structure

[Jan Beulich <jbeulich@xxxxxxxx>]

This can now also be used to reduce the number of parameters
x86emul_fpu() needs to take.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
---
We could of course set the struct field once early in x86_emulate(), but
for now I think we're better off leaving it as NULL where not actually
needed.

--- a/xen/arch/x86/x86_emulate/fpu.c
+++ b/xen/arch/x86/x86_emulate/fpu.c
@@ -90,9 +90,8 @@ int x86emul_fpu(struct x86_emulate_state
                 unsigned int *insn_bytes,
                 enum x86_emulate_fpu_type *fpu_type,
 #define fpu_type (*fpu_type) /* for get_fpu() */
-                struct stub_exn *stub_exn,
-#define stub_exn (*stub_exn) /* for invoke_stub() */
                 mmval_t *mmvalp)
+#define stub_exn (*s->stub_exn) /* for invoke_stub() */
 {
     uint8_t b;
     int rc;
--- a/xen/arch/x86/x86_emulate/private.h
+++ b/xen/arch/x86/x86_emulate/private.h
@@ -764,7 +764,6 @@ int x86emul_fpu(struct x86_emulate_state
                 const struct x86_emulate_ops *ops,
                 unsigned int *insn_bytes,
                 enum x86_emulate_fpu_type *fpu_type,
-                struct stub_exn *stub_exn,
                 mmval_t *mmvalp);
 int x86emul_0f01(struct x86_emulate_state *s,
                  struct cpu_user_regs *regs,
--- a/xen/arch/x86/x86_emulate/x86_emulate.c
+++ b/xen/arch/x86/x86_emulate/x86_emulate.c
@@ -2058,8 +2058,9 @@ x86_emulate(
 #ifndef X86EMUL_NO_FPU
     case 0x9b:  /* wait/fwait */
     case 0xd8 ... 0xdf: /* FPU */
+        state->stub_exn = &stub_exn;
         rc = x86emul_fpu(state, &_regs, &dst, &src, ctxt, ops,
-                         &insn_bytes, &fpu_type, &stub_exn, mmvalp);
+                         &insn_bytes, &fpu_type, mmvalp);
         goto dispatch_from_helper;
 #endif