diff --git a/xen/arch/x86/cpu/microcode/amd.c b/xen/arch/x86/cpu/microcode/amd.c
index c6d13f3fb3..b28171f2d4 100644
--- a/xen/arch/x86/cpu/microcode/amd.c
+++ b/xen/arch/x86/cpu/microcode/amd.c
@@ -222,12 +222,15 @@ static int cf_check apply_microcode(const struct microcode_patch *patch)
     uint32_t rev, old_rev = sig->rev;
     enum microcode_match_result result = microcode_fits(patch);
 
+    if ( result == MIS_UCODE )
+        return -EINVAL;
+
     /*
      * Allow application of the same revision to pick up SMT-specific changes
      * even if the revision of the other SMT thread is already up-to-date.
      */
-    if ( result != NEW_UCODE && result != SAME_UCODE )
-        return -EINVAL;
+    if ( result == OLD_UCODE )
+        return -EEXIST;
 
     if ( check_final_patch_levels(sig) )
     {
diff --git a/xen/arch/x86/cpu/microcode/core.c b/xen/arch/x86/cpu/microcode/core.c
index 667b1baf91..3150395478 100644
--- a/xen/arch/x86/cpu/microcode/core.c
+++ b/xen/arch/x86/cpu/microcode/core.c
@@ -819,6 +819,8 @@ int __init early_microcode_init(void)
 
     alternative_vcall(ucode_ops.collect_cpu_info);
 
+    printk(XENLOG_INFO "BSP microcode revision: 0x%08x\n", this_cpu(cpu_sig).rev);
+
     if ( ucode_mod.mod_end || ucode_blob.size )
         rc = early_microcode_update_cpu();
 
diff --git a/xen/arch/x86/cpu/microcode/intel.c b/xen/arch/x86/cpu/microcode/intel.c
index cb08f63d2e..91d82f9dde 100644
--- a/xen/arch/x86/cpu/microcode/intel.c
+++ b/xen/arch/x86/cpu/microcode/intel.c
@@ -294,10 +294,13 @@ static int cf_check apply_microcode(const struct microcode_patch *patch)
 
     result = microcode_update_match(patch);
 
-    if ( result != NEW_UCODE &&
-         !(opt_ucode_allow_same && result == SAME_UCODE) )
+    if ( result == MIS_UCODE )
         return -EINVAL;
 
+    if ( result == OLD_UCODE ||
+         (result == SAME_UCODE && !opt_ucode_allow_same) )
+        return -EEXIST;
+
     wbinvd();
 
     wrmsrl(MSR_IA32_UCODE_WRITE, (unsigned long)patch->data);