target-i386: Fix SSE status flag corruption

When we restore the mxcsr register with FXRSTOR, or set it with gdb,
we need to update the various SSE status flags in CPUX86State
Reported-by: NRichard Purdie <richard.purdie@linuxfoundation.org>
Reviewed-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NRichard Henderson <rth@twiddle.net>

target-i386/cpu.h

@@ -1259,6 +1259,9 @@ static inline void cpu_load_efer(CPUX86State *env, uint64_t val)
     }
 }
 
+/* fpu_helper.c */
+void cpu_set_mxcsr(CPUX86State *env, uint32_t val);
+
 /* svm_helper.c */
 void cpu_svm_check_intercept_param(CPUX86State *env1, uint32_t type,
                                    uint64_t param);

target-i386/fpu_helper.c

@@ -1179,7 +1179,7 @@ void helper_fxrstor(CPUX86State *env, target_ulong ptr, int data64)
 
     if (env->cr[4] & CR4_OSFXSR_MASK) {
         /* XXX: finish it */
-        env->mxcsr = cpu_ldl_data(env, ptr + 0x18);
+        cpu_set_mxcsr(env, cpu_ldl_data(env, ptr + 0x18));
         /* cpu_ldl_data(env, ptr + 0x1c); */
         if (env->hflags & HF_CS64_MASK) {
             nb_xmm_regs = 16;
@@ -1229,12 +1229,14 @@ floatx80 cpu_set_fp80(uint64_t mant, uint16_t upper)
 #define SSE_RC_CHOP         0x6000
 #define SSE_FZ              0x8000
 
-static void update_sse_status(CPUX86State *env)
+void cpu_set_mxcsr(CPUX86State *env, uint32_t mxcsr)
 {
     int rnd_type;
 
+    env->mxcsr = mxcsr;
+
     /* set rounding mode */
-    switch (env->mxcsr & SSE_RC_MASK) {
+    switch (mxcsr & SSE_RC_MASK) {
     default:
     case SSE_RC_NEAR:
         rnd_type = float_round_nearest_even;
@@ -1252,16 +1254,15 @@ static void update_sse_status(CPUX86State *env)
     set_float_rounding_mode(rnd_type, &env->sse_status);
 
     /* set denormals are zero */
-    set_flush_inputs_to_zero((env->mxcsr & SSE_DAZ) ? 1 : 0, &env->sse_status);
+    set_flush_inputs_to_zero((mxcsr & SSE_DAZ) ? 1 : 0, &env->sse_status);
 
     /* set flush to zero */
-    set_flush_to_zero((env->mxcsr & SSE_FZ) ? 1 : 0, &env->fp_status);
+    set_flush_to_zero((mxcsr & SSE_FZ) ? 1 : 0, &env->fp_status);
 }
 
 void helper_ldmxcsr(CPUX86State *env, uint32_t val)
 {
-    env->mxcsr = val;
-    update_sse_status(env);
+    cpu_set_mxcsr(env, val);
 }
 
 void helper_enter_mmx(CPUX86State *env)

target-i386/gdbstub.c

@@ -222,7 +222,7 @@ int x86_cpu_gdb_write_register(CPUState *cs, uint8_t *mem_buf, int n)
             return 4;
 
         case IDX_MXCSR_REG:
-            env->mxcsr = ldl_p(mem_buf);
+            cpu_set_mxcsr(env, ldl_p(mem_buf));
             return 4;
         }
     }