fix: don't default to 0x0 ucode when unknown

src/libs/350_cpu_detect2.sh

@@ -147,8 +147,8 @@ parse_cpu_details() {
         fi
     fi
 
-    # if we got no cpu_ucode (e.g. we're in a vm), fall back to 0x0
-    : "${cpu_ucode:=0x0}"
+    # if we got no cpu_ucode (e.g. we're in a vm), leave it empty
+    # so that we can detect this case and avoid false positives
 
     # on non-x86 systems (e.g. ARM), these fields may not exist in cpuinfo, fall back to 0
     : "${cpu_family:=0}"
@@ -163,9 +163,11 @@ parse_cpu_details() {
         g_mockme=$(printf "%b\n%b" "$g_mockme" "SMC_MOCK_CPU_UCODE='$cpu_ucode'")
     fi
 
-    echo "$cpu_ucode" | grep -q ^0x && cpu_ucode=$((cpu_ucode))
-    g_ucode_found=$(printf "family 0x%x model 0x%x stepping 0x%x ucode 0x%x cpuid 0x%x pfid 0x%x" \
-        "$cpu_family" "$cpu_model" "$cpu_stepping" "$cpu_ucode" "$cpu_cpuid" "$cpu_platformid")
+    if [ -n "$cpu_ucode" ]; then
+        echo "$cpu_ucode" | grep -q ^0x && cpu_ucode=$((cpu_ucode))
+    fi
+    g_ucode_found=$(printf "family 0x%x model 0x%x stepping 0x%x ucode 0x%s cpuid 0x%x pfid 0x%x" \
+        "$cpu_family" "$cpu_model" "$cpu_stepping" "${cpu_ucode:-unknown}" "$cpu_cpuid" "$cpu_platformid")
 
     g_parse_cpu_details_done=1
 }

src/libs/360_cpu_smt.sh

@@ -210,7 +210,7 @@ has_zenbleed_fixed_firmware() {
         model_high=$(echo "$tuple" | cut -d, -f2)
         fwver=$(echo "$tuple" | cut -d, -f3)
         if [ $((cpu_model)) -ge $((model_low)) ] && [ $((cpu_model)) -le $((model_high)) ]; then
-            if [ $((cpu_ucode)) -ge $((fwver)) ]; then
+            if [ -n "$cpu_ucode" ] && [ $((cpu_ucode)) -ge $((fwver)) ]; then
                 g_zenbleed_fw=0 # true
                 break
             else

src/libs/380_hw_microcode.sh

@@ -42,6 +42,10 @@ is_latest_known_ucode() {
         ret_is_latest_known_ucode_latest="couldn't get your cpuid"
         return 2
     fi
+    if [ -z "$cpu_ucode" ]; then
+        ret_is_latest_known_ucode_latest="couldn't get your microcode version"
+        return 2
+    fi
     ret_is_latest_known_ucode_latest="latest microcode version for your CPU model is unknown"
     if is_intel; then
         brand_prefix=I