From: Lennart Poettering <lennart@poettering.net>
Date: Tue, 22 Feb 2011 00:39:19 +0000 (+0100)
Subject: virtualization: check cpuid first, since it is cheaper than DMI
X-Git-Tag: v19~34
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=721bca5763a9e2befebc84b37c6d537990d4ce6e;p=systemd

virtualization: check cpuid first, since it is cheaper than DMI
---

diff --git a/src/util.c b/src/util.c
index aa49390b..e2859faf 100644
--- a/src/util.c
+++ b/src/util.c
@@ -3713,7 +3713,7 @@ int detect_vm(const char **id) {
 
         /* Both CPUID and DMI are x86 specific interfaces... */
 
-        const char *const dmi_vendors[] = {
+        static const char *const dmi_vendors[] = {
                 "/sys/class/dmi/id/sys_vendor",
                 "/sys/class/dmi/id/board_vendor",
                 "/sys/class/dmi/id/bios_vendor"
@@ -3727,6 +3727,7 @@ int detect_vm(const char **id) {
                 "Microsoft Corporation\0" "microsoft\0"
                 "innotek GmbH\0"          "oracle\0"
                 "Xen\0"                   "xen\0"
+                "Bochs\0"                 "bochs\0"
                 "\0";
 
         static const char cpuid_vendor_table[] =
@@ -3743,34 +3744,9 @@ int detect_vm(const char **id) {
                 uint32_t sig32[3];
                 char text[13];
         } sig;
-
         unsigned i;
         const char *j, *k;
-
-        for (i = 0; i < ELEMENTSOF(dmi_vendors); i++) {
-                char *s;
-                int r;
-                const char *found = NULL;
-
-                if ((r = read_one_line_file(dmi_vendors[i], &s)) < 0) {
-                        if (r != -ENOENT)
-                                return r;
-
-                        continue;
-                }
-
-                NULSTR_FOREACH_PAIR(j, k, dmi_vendor_table)
-                        if (startswith(s, j))
-                                found = k;
-                free(s);
-
-                if (found) {
-                        if (id)
-                                *id = found;
-
-                        return 1;
-                }
-        }
+        bool hypervisor;
 
         /* http://lwn.net/Articles/301888/ */
         zero(sig);
@@ -3795,7 +3771,9 @@ int detect_vm(const char **id) {
                 : "0" (eax)
         );
 
-        if (ecx & 0x80000000U) {
+        hypervisor = !!(ecx & ecx & 0x80000000U);
+
+        if (hypervisor) {
 
                 /* There is a hypervisor, see what it is */
                 eax = 0x40000000U;
@@ -3818,14 +3796,41 @@ int detect_vm(const char **id) {
 
                                 return 1;
                         }
+        }
 
+        for (i = 0; i < ELEMENTSOF(dmi_vendors); i++) {
+                char *s;
+                int r;
+                const char *found = NULL;
+
+                if ((r = read_one_line_file(dmi_vendors[i], &s)) < 0) {
+                        if (r != -ENOENT)
+                                return r;
+
+                        continue;
+                }
+
+                NULSTR_FOREACH_PAIR(j, k, dmi_vendor_table)
+                        if (startswith(s, j))
+                                found = k;
+                free(s);
+
+                if (found) {
+                        if (id)
+                                *id = found;
+
+                        return 1;
+                }
+        }
+
+        if (hypervisor) {
                 if (id)
                         *id = "other";
 
                 return 1;
         }
-#endif
 
+#endif
         return 0;
 }