Changeset 49784 in vbox for trunk/src/VBox/HostDrivers

Timestamp:

Dec 5, 2013 10:30:06 AM (11 years ago)

Author:

vboxsync

Message:

HostDrivers: Fix SUPR0QueryVTCaps() to be preemption safe.

File:

• trunk/src/VBox/HostDrivers/Support/SUPDrv.c (modified) (4 diffs)

trunk/src/VBox/HostDrivers/Support/SUPDrv.c

@@ -3398 +3398 @@
 SUPR0DECL(int) SUPR0QueryVTCaps(PSUPDRVSESSION pSession, uint32_t *pfCaps)
 {
+    int rc = VERR_UNSUPPORTED_CPU;
+    RTTHREADPREEMPTSTATE PreemptState = RTTHREADPREEMPTSTATE_INITIALIZER;
+
     /*
      * Input validation.
@@ -3405 +3408 @@
 
     *pfCaps = 0;
-
-    /** @todo r=ramshankar: Although we're only reading CPUIDs/MSRs here which
-     *        should be identical on all CPUs on the system, it's probably
-     *        cleaner to prevent migration nonetheless? */
+    /* We may modify MSRs and re-read them, disable preemption so we make sure we don't migrate CPUs. */
+    RTThreadPreemptDisable(&PreemptState);
     if (ASMHasCpuId())
     {
@@ -3485 +3486 @@
                             *pfCaps |= SUPVTCAPS_NESTED_PAGING;
                     }
-                    return VINF_SUCCESS;
                 }
-                return rc;
             }
-            return VERR_VMX_NO_VMX;
-        }
-
-        if (   ASMIsAmdCpuEx(uVendorEBX, uVendorECX, uVendorEDX)
-            && ASMIsValidStdRange(uMaxId))
+            else
+                rc = VERR_VMX_NO_VMX;
+        }
+        else if (   ASMIsAmdCpuEx(uVendorEBX, uVendorECX, uVendorEDX)
+                 && ASMIsValidStdRange(uMaxId))
         {
             uint32_t fExtFeaturesEcx, uExtMaxId;
@@ -3517 +3516 @@
                         *pfCaps |= SUPVTCAPS_NESTED_PAGING;
 
-                    return VINF_SUCCESS;
+                    rc = VINF_SUCCESS;
                 }
-                return VERR_SVM_DISABLED;
+                else
+                    rc = VERR_SVM_DISABLED;
             }
-            return VERR_SVM_NO_SVM;
-        }
-    }
-
-    return VERR_UNSUPPORTED_CPU;
+            else
+                rc = VERR_SVM_NO_SVM;
+        }
+    }
+
+    RTThreadPreemptRestore(&PreemptState);
+    return rc;
 }