boot-timestamps: Discard firmware init time when running in a VM

medhefgo · keszybz · commit f699bd81e8e1 · 2022-01-09T19:21:16.000+01:00
Fixes: systemd#22060
diff --git a/src/shared/boot-timestamps.c b/src/shared/boot-timestamps.c
@@ -5,11 +5,13 @@
 #include "efi-loader.h"
 #include "macro.h"
 #include "time-util.h"
+#include "virt.h"
 
 int boot_timestamps(const dual_timestamp *n, dual_timestamp *firmware, dual_timestamp *loader) {
         usec_t x = 0, y = 0, a;
         int r;
         dual_timestamp _n;
+        bool use_firmware = true;
 
         assert(firmware);
         assert(loader);
@@ -24,6 +26,10 @@ int boot_timestamps(const dual_timestamp *n, dual_timestamp *firmware, dual_time
                 r = efi_loader_get_boot_usec(&x, &y);
                 if (r < 0)
                         return r;
+
+                /* If we are running in a VM, the init timestamp would
+                 * be equivalent to the host uptime. */
+                use_firmware = detect_vm() <= 0;
         }
 
         /* Let's convert this to timestamps where the firmware
@@ -33,12 +39,14 @@ int boot_timestamps(const dual_timestamp *n, dual_timestamp *firmware, dual_time
          * the monotonic timestamps here as negative of the actual
          * value. */
 
-        firmware->monotonic = y;
-        loader->monotonic = y - x;
-
-        a = n->monotonic + firmware->monotonic;
-        firmware->realtime = n->realtime > a ? n->realtime - a : 0;
+        if (use_firmware) {
+                firmware->monotonic = y;
+                a = n->monotonic + firmware->monotonic;
+                firmware->realtime = n->realtime > a ? n->realtime - a : 0;
+        } else
+                firmware->monotonic = firmware->realtime = 0;
 
+        loader->monotonic = y - x;
         a = n->monotonic + loader->monotonic;
         loader->realtime = n->realtime > a ? n->realtime - a : 0;
 
