save/restore fix

diff -r e43ef79379e1 xen/arch/x86/hvm/hvm.c
@@ -189,9 +189,26 @@ void hvm_domain_destroy(struct domain *d
         unmap_domain_page_global((void *)d->arch.hvm_domain.buffered_io_va);
 }
 
+#define HVM_VCPU_CTXT_MAGIC 0x85963130
+void hvm_save_cpu_ctxt(hvm_domain_context_t *h, void *opaque)
+{
+    struct vcpu *v = opaque;
+
+    if ( test_bit(_VCPUF_down, &v->vcpu_flags) ) {
+        hvm_put_32u(h, 0x0);
+        return;
+    }
+
+    hvm_put_32u(h, HVM_VCPU_CTXT_MAGIC);
+    hvm_funcs.save_cpu_ctxt(h, opaque);
+}
+
 int hvm_load_cpu_ctxt(hvm_domain_context_t *h, void *opaque, int version)
 {
     struct vcpu *v = opaque;
+
+    if ( hvm_get_32u(h) != HVM_VCPU_CTXT_MAGIC )
+        return 0;
 
     if ( hvm_funcs.load_cpu_ctxt(h, opaque, version) < 0 )
         return -EINVAL;

@@ -208,7 +225,7 @@ int hvm_vcpu_initialise(struct vcpu *v)
     int rc;
 
     hvm_register_savevm(v->domain, "xen_hvm_cpu", v->vcpu_id, 1,
-                        hvm_funcs.save_cpu_ctxt, hvm_load_cpu_ctxt, 
+                        hvm_save_cpu_ctxt, hvm_load_cpu_ctxt, 
                         (void *)v);
 
     if ( (rc = vlapic_init(v)) != 0 )

diff -r e43ef79379e1 xen/include/public/domctl.h
@@ -386,7 +386,7 @@ typedef struct xen_domctl_settimeoffset 
 typedef struct xen_domctl_settimeoffset xen_domctl_settimeoffset_t;
 DEFINE_XEN_GUEST_HANDLE(xen_domctl_settimeoffset_t);
  
-#define HVM_CTXT_SIZE        6144
+#define HVM_CTXT_SIZE        8192
 typedef struct hvm_domain_context {
     uint32_t cur;
     uint32_t size;