i386: correct cpu_x86_cpuid(0xd)

Intel SDM says for CPUID function 0DH, sub-function 0:

| • ECX enumerates the size (in bytes) required by the XSAVE instruction for an
|   XSAVE area containing all the user state components supported by this
|   processor.
| • EBX enumerates the size (in bytes) required by the XSAVE instruction for an
|   XSAVE area containing all the user state components corresponding to bits
|   currently set in XCR0.
Signed-off-by: NSebastian Andrzej Siewior <bigeasy@linutronix.de>
Message-Id: <20180928104319.3296-1-bigeasy@linutronix.de>
Reviewed-by: NEduardo Habkost <ehabkost@redhat.com>
Signed-off-by: NEduardo Habkost <ehabkost@redhat.com>

target/i386/cpu.c

@@ -4178,7 +4178,7 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index, uint32_t count,
             *ecx = xsave_area_size(x86_cpu_xsave_components(cpu));
             *eax = env->features[FEAT_XSAVE_COMP_LO];
             *edx = env->features[FEAT_XSAVE_COMP_HI];
-            *ebx = *ecx;
+            *ebx = xsave_area_size(env->xcr0);
         } else if (count == 1) {
             *eax = env->features[FEAT_XSAVE];
         } else if (count < ARRAY_SIZE(x86_ext_save_areas)) {