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List:       ltp-list
Subject:    [LTP] [PATCH 1/2] lib: provide a way to detect if we are running on KVM or Xen
From:       "Wei,Jiangang" <weijg.fnst () cn ! fujitsu ! com>
Date:       2015-02-24 8:27:38
Message-ID: 1424766459-22439-1-git-send-email-weijg.fnst () cn ! fujitsu ! com
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The command virt-what can be used to detect if the program is
running in a virtual machine, and prints out a list of "facts"
about the virtual machine. such as hyperv, lxc, qemu, kvm, xen
and so on.

Refer to the following for more details,
<http://people.redhat.com/~rjones/virt-what/>

This patch references the method that has already proposed
and implemented in the code of virt-what.

Signed-off-by: Wei,Jiangang <weijg.fnst@cn.fujitsu.com>
---
 lib/tst_virt.c | 69 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 69 insertions(+)

diff --git a/lib/tst_virt.c b/lib/tst_virt.c
index 87f73dc..eb3b487 100644
--- a/lib/tst_virt.c
+++ b/lib/tst_virt.c
@@ -23,9 +23,78 @@
  */
 
 #include <unistd.h>
+#include <string.h>
 #include "test.h"
 #include "safe_macros.h"
 
+#define SIG_MAX_LEN 13  // Limit the length of the CPU sign array
+
+#if defined(__i386__) || defined(__x86_64__)
+
+static unsigned int
+cpuid (unsigned int eax, char *sigp)
+{
+    unsigned int *sig32 = (unsigned int *) sigp;
+
+    asm volatile (
+        "xor %%ebx, %%ebx; cpuid"
+        : "=a" (eax), "=b" (sig32[0]), "=c" (sig32[1]), "=d" (sig32[2])
+        : "0" (eax));
+    sigp[SIG_MAX_LEN - 1] = 0;
+
+    return eax;
+}
+
+/*
+ * confirm that we are running inside KVM or Xen HVM by CPU sign
+ *
+ * Inputs:
+ *   char* sigp - the pointer of CPU sign array, sig[].
+ *                Possible Values of sig[]:
+ *                  String        - Virtual Type
+ *                  KVMKVMKVM     - KVM guest
+ *                  XenVMMXenVMM  - Xen HVM guest
+ *
+ * Returns:
+ *   0  - success
+ *   -1 - an error has occurred (unsupported architecture)
+ */
+static int
+cpu_sign (char* sigp)
+{
+    unsigned int base = 0x40000000, leaf = base;
+    unsigned int max_entries;
+
+    memset (sigp, 0, SIG_MAX_LEN);
+    max_entries = cpuid (leaf, sigp);
+
+    /* Most hypervisors only have information in leaf 0x40000000, but
+     * upstream Xen contains further leaf entries (in particular when
+     * used with Viridian [HyperV] extensions).  CPUID is supposed to
+     * return the maximum leaf offset in %eax, so that's what we use,
+     * but only if it looks sensible.
+     */
+    if (max_entries > 3 && max_entries < 0x10000) {
+        for (leaf = base + 0x100; leaf <= base + max_entries; leaf += 0x100) {
+            memset (sigp, 0, SIG_MAX_LEN);
+            cpuid (leaf, sigp);
+        }
+    }
+
+    return 0;
+}
+
+#else /* !i386, !x86_64 */
+
+static int
+cpu_sign (char* sigp)
+{
+    /* nothing for other architectures */
+    return -1;
+}
+
+#endif
+
 static int is_kvm(void)
 {
 	FILE *cpuinfo;
-- 
1.9.3


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