i386: Save EFER for 32-bit targets

i386 (32 bit) emulation uses EFER in wrmsr and in MMU fault
processing.
But it does not included in VMState, because "efer" field is disabled with

This patch adds a section for 32-bit targets which saves EFER when
it's value is non-zero.

Signed-off-by: Pavel Dovgalyuk <pavel.dovgaluk@ispras.ru>
Message-Id: <155913371654.8429.1659082639780315242.stgit@pasha-Precision-3630-Tower>
Reviewed-by: Peter Xu <peterx@redhat.com>
[ehabkost: indentation fix]
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>

target/i386/machine.c

@@ -964,6 +964,27 @@ static const VMStateDescription vmstate_svm_npt = {
     }
 };
 
+#ifndef TARGET_X86_64
+static bool intel_efer32_needed(void *opaque)
+{
+    X86CPU *cpu = opaque;
+    CPUX86State *env = &cpu->env;
+
+    return env->efer != 0;
+}
+
+static const VMStateDescription vmstate_efer32 = {
+    .name = "cpu/efer32",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .needed = intel_efer32_needed,
+    .fields = (VMStateField[]) {
+        VMSTATE_UINT64(env.efer, X86CPU),
+        VMSTATE_END_OF_LIST()
+    }
+};
+#endif
+
 VMStateDescription vmstate_x86_cpu = {
     .name = "cpu",
     .version_id = 12,
@@ -1089,6 +1110,9 @@ VMStateDescription vmstate_x86_cpu = {
         &vmstate_msr_intel_pt,
         &vmstate_msr_virt_ssbd,
         &vmstate_svm_npt,
+#ifndef TARGET_X86_64
+        &vmstate_efer32,
+#endif
         NULL
     }
 };