x86/hvm: introduce viridian_save_vcpu_ctxt_one()

This is used to save data from a single instance.

Signed-off-by: Alexandru Isaila <aisaila@bitdefender.com>
Reviewed-by: Paul Durrant <paul.durrant@citrix.com>

xen/arch/x86/hvm/viridian.c

@@ -1030,24 +1030,32 @@ static int viridian_load_domain_ctxt(struct domain *d, hvm_domain_context_t *h)
 HVM_REGISTER_SAVE_RESTORE(VIRIDIAN_DOMAIN, viridian_save_domain_ctxt,
                           viridian_load_domain_ctxt, 1, HVMSR_PER_DOM);
 
+static int viridian_save_vcpu_ctxt_one(struct vcpu *v, hvm_domain_context_t *h)
+{
+    struct hvm_viridian_vcpu_context ctxt = {
+        .vp_assist_msr = v->arch.hvm.viridian.vp_assist.msr.raw,
+        .vp_assist_pending = v->arch.hvm.viridian.vp_assist.pending,
+    };
+
+    if ( !is_viridian_domain(v->domain) )
+        return 0;
+
+    return hvm_save_entry(VIRIDIAN_VCPU, v->vcpu_id, h, &ctxt);
+}
+
 static int viridian_save_vcpu_ctxt(struct domain *d, hvm_domain_context_t *h)
 {
     struct vcpu *v;
+    int err = 0;
 
-    if ( !is_viridian_domain(d) )
-        return 0;
-
-    for_each_vcpu( d, v ) {
-        struct hvm_viridian_vcpu_context ctxt = {
-            .vp_assist_msr = v->arch.hvm.viridian.vp_assist.msr.raw,
-            .vp_assist_pending = v->arch.hvm.viridian.vp_assist.pending,
-        };
-
-        if ( hvm_save_entry(VIRIDIAN_VCPU, v->vcpu_id, h, &ctxt) != 0 )
-            return 1;
+    for_each_vcpu ( d, v )
+    {
+        err = viridian_save_vcpu_ctxt_one(v, h);
+        if ( err )
+            break;
     }
 
-    return 0;
+    return err;
 }
 
 static int viridian_load_vcpu_ctxt(struct domain *d, hvm_domain_context_t *h)