virt: swap order of cpuid and dmi again, but properly detect oracle (#5355)

This breaks again, this time for setups where Qemu is not reported via DMI for whatever
reason. So swap order of cpuid and dmi again, but properly detect oracle.

See issue #5318.

2 files changed, 14 insertions, 14 deletions

diff --git a/man/systemd-detect-virt.xml b/man/systemd-detect-virt.xml
index dc10b4dd43..72ea35892f 100644
--- a/man/systemd-detect-virt.xml
+++ b/man/systemd-detect-virt.xml
@@ -96,7 +96,8 @@
 
           <row>
             <entry><varname>kvm</varname></entry>
-            <entry>Linux KVM kernel virtual machine, from within QEMU</entry>
+            <entry>Linux KVM kernel virtual machine, with whatever software, except
+            Oracle Virtualbox</entry>
           </row>
 
           <row>
@@ -116,7 +117,8 @@
 
           <row>
             <entry><varname>oracle</varname></entry>
-            <entry>Oracle VM VirtualBox (historically marketed by innotek and Sun Microsystems)</entry>
+            <entry>Oracle VM VirtualBox (historically marketed by innotek and Sun Microsystems),
+            for legacy and KVM hypervisor</entry>
           </row>
 
           <row>
diff --git a/src/basic/virt.c b/src/basic/virt.c
index 0fbbdea602..830dc655e3 100644
--- a/src/basic/virt.c
+++ b/src/basic/virt.c
@@ -316,31 +316,29 @@ static int detect_vm_zvm(void) {
 /* Returns a short identifier for the various VM implementations */
 int detect_vm(void) {
         static thread_local int cached_found = _VIRTUALIZATION_INVALID;
-        int r, cpuid;
+        int r, dmi;
 
         if (cached_found >= 0)
                 return cached_found;
 
         /* We have to use the correct order here:
          *
-         * -> First try to detect qemu/kvm and return 'kvm'.
-         * -> Some virtualization technologies do use KVM hypervisor but are
-         *    expected to be detected as something else. Virtualbox since
-         *    version 5.0 is an example. So detect DMI next.
-         * -> Get infos from CPUID third. */
+         * -> First try to detect Oracle Virtualbox, even if it uses KVM.
+         * -> Second try to detect from cpuid, this will report KVM for
+         *    whatever software is used even if info in dmi is overwritten.
+         * -> Third try to detect from dmi. */
 
-        cpuid = detect_vm_cpuid();
-        r = detect_vm_dmi();
-
-        if (r == VIRTUALIZATION_QEMU && cpuid == VIRTUALIZATION_KVM)
-                return cpuid;
+        dmi = detect_vm_dmi();
+        if (dmi == VIRTUALIZATION_ORACLE)
+                return dmi;
 
+        r = detect_vm_cpuid();
         if (r < 0)
                 return r;
         if (r != VIRTUALIZATION_NONE)
                 goto finish;
 
-        r = cpuid;
+        r = dmi;
         if (r < 0)
                 return r;
         if (r != VIRTUALIZATION_NONE)