Changeset 70917 in vbox for trunk/src/VBox/HostDrivers/Support/win

Timestamp:

Feb 8, 2018 3:56:43 PM (7 years ago)

Author:

vboxsync

Message:

SUPDrv,VMM: Added SUPR0GetRawModeUsability() for checking whether we're allowed to modify CR4 under Hyper-V. It's called from VMMR0/ModuleInit and the result is cached in a global variable and checked before we call into RC.

File:

• trunk/src/VBox/HostDrivers/Support/win/SUPDrv-win.cpp (modified) (2 diffs)

trunk/src/VBox/HostDrivers/Support/win/SUPDrv-win.cpp

@@ -46 +46 @@
 #include <iprt/spinlock.h>
 #include <iprt/string.h>
+#include <iprt/x86.h>
 #include <VBox/log.h>
 #include <VBox/err.h>
@@ -1873 +1874 @@
 
 
+/**
+ * Checks whether we're allowed by Hyper-V to modify CR4.
+ */
+int  VBOXCALL supdrvOSGetRawModeUsability(void)
+{
+    int rc = VINF_SUCCESS;
+
+#ifdef RT_ARCH_AMD64
+    /*
+     * Broadwell running W10 17083.100:
+     *        CR4: 0x170678
+     *  Evil mask: 0x170638
+     *      X86_CR4_SMEP        - evil
+     *      X86_CR4_FSGSBASE    - evil
+     *      X86_CR4_PCIDE       - evil
+     *      X86_CR4_OSXSAVE     - evil
+     *      X86_CR4_OSFXSR      - evil
+     *      X86_CR4_OSXMMEEXCPT - evil
+     *      X86_CR4_PSE         - evil
+     *      X86_CR4_PAE         - evil
+     *      X86_CR4_MCE         - okay
+     *      X86_CR4_DE          - evil
+     */
+    if (ASMHasCpuId())
+    {
+        uint32_t cStd = ASMCpuId_EAX(0);
+        if (ASMIsValidStdRange(cStd))
+        {
+            uint32_t uIgn         = 0;
+            uint32_t fEdxFeatures = 0;
+            uint32_t fEcxFeatures = 0;
+            ASMCpuIdExSlow(1, 0, 0, 0, &uIgn, &uIgn, &fEcxFeatures, &fEdxFeatures);
+            if (fEcxFeatures & X86_CPUID_FEATURE_ECX_HVP)
+            {
+                RTCCUINTREG  const fOldFlags    = ASMIntDisableFlags();
+                RTCCUINTXREG const fCr4         = ASMGetCR4();
+
+                RTCCUINTXREG const fSafeToClear = X86_CR4_TSD      | X86_CR4_DE     | X86_CR4_PGE  | X86_CR4_PCE
+                                                | X86_CR4_FSGSBASE | X86_CR4_PCIDE  | X86_CR4_SMEP | X86_CR4_SMAP
+                                                | X86_CR4_OSXSAVE  | X86_CR4_OSFXSR | X86_CR4_OSXMMEEXCPT;
+                RTCCUINTXREG       fLoadCr4     = fCr4 & ~fSafeToClear;
+                RTCCUINTXREG const fCleared     = fCr4 & fSafeToClear;
+                if (!(fCleared & X86_CR4_TSD) && (fEdxFeatures & X86_CPUID_FEATURE_EDX_TSC))
+                    fLoadCr4 |= X86_CR4_TSD;
+                if (!(fCleared & X86_CR4_PGE) && (fEdxFeatures & X86_CPUID_FEATURE_EDX_PGE))
+                    fLoadCr4 |= X86_CR4_PGE;
+                __try
+                {
+                    ASMSetCR4(fLoadCr4);
+                }
+                __except(EXCEPTION_EXECUTE_HANDLER)
+                {
+                    rc = VERR_SUPDRV_NO_RAW_MODE_HYPER_V_ROOT;
+                }
+                if (RT_SUCCESS(rc))
+                    ASMSetCR4(fCr4);
+                ASMSetFlags(fOldFlags);
+            }
+        }
+    }
+#endif
+    return rc;
+}
+
+
 #define MY_SystemLoadGdiDriverInSystemSpaceInformation  54
 #define MY_SystemUnloadGdiDriverInformation             27