4 files changed, 84 insertions, 48 deletions
diff --git a/src/Common/Dlgcode.c b/src/Common/Dlgcode.c
index c9955714..1ecc3c0a 100644
--- a/src/Common/Dlgcode.c
+++ b/src/Common/Dlgcode.c
@@ -5517,12 +5517,13 @@ BOOL CALLBACK BenchmarkDlgProc (HWND hwndDlg, UINT msg, WPARAM wParam, LPARAM lP
 
 
 			uint32 driverConfig = ReadDriverConfigurationFlags();
+			int isAesHwSupported = is_aes_hw_cpu_supported();
 
-			SetDlgItemTextW (hwndDlg, IDC_HW_AES, (wstring (L" ") + (GetString (is_aes_hw_cpu_supported() ? ((driverConfig & TC_DRIVER_CONFIG_DISABLE_HARDWARE_ENCRYPTION) ? "UISTR_DISABLED" : "UISTR_YES") : "NOT_APPLICABLE_OR_NOT_AVAILABLE"))).c_str());
+			SetDlgItemTextW (hwndDlg, IDC_HW_AES, (wstring (L" ") + (GetString (isAesHwSupported ? ((driverConfig & TC_DRIVER_CONFIG_DISABLE_HARDWARE_ENCRYPTION) ? "UISTR_DISABLED" : "UISTR_YES") : "NOT_APPLICABLE_OR_NOT_AVAILABLE"))).c_str());
 
 			ToHyperlink (hwndDlg, IDC_HW_AES_LABEL_LINK);
 
-			if (is_aes_hw_cpu_supported() && (driverConfig & TC_DRIVER_CONFIG_DISABLE_HARDWARE_ENCRYPTION))
+			if (isAesHwSupported && (driverConfig & TC_DRIVER_CONFIG_DISABLE_HARDWARE_ENCRYPTION))
 			{
 				Warning ("DISABLED_HW_AES_AFFECTS_PERFORMANCE", hwndDlg);
 			}
diff --git a/src/Crypto/Aes_hw_cpu.asm b/src/Crypto/Aes_hw_cpu.asm
index faaba4f3..edc20b29 100644
--- a/src/Crypto/Aes_hw_cpu.asm
+++ b/src/Crypto/Aes_hw_cpu.asm
@@ -286,17 +286,20 @@
 
 ; byte is_aes_hw_cpu_supported ();
 
-	export_function is_aes_hw_cpu_supported
-		push %[R]bx
-
-		mov eax, 1
-		cpuid
-		mov eax, ecx
-		shr eax, 25
-		and eax, 1
-
-		pop %[R]bx
-	ret
+; We comment this since we have an alternative C implementation
+; that supports Hyper-V detection workaround
+;
+;	export_function is_aes_hw_cpu_supported
+;		push %[R]bx
+;
+;		mov eax, 1
+;		cpuid
+;		mov eax, ecx
+;		shr eax, 25
+;		and eax, 1
+;
+;		pop %[R]bx
+;	ret
 
 
 ; void aes_hw_cpu_decrypt (const byte *ks, byte *data);
diff --git a/src/Crypto/cpu.c b/src/Crypto/cpu.c
index 53e5e686..5743e6fc 100644
--- a/src/Crypto/cpu.c
+++ b/src/Crypto/cpu.c
@@ -192,6 +192,47 @@ VC_INLINE int IsAMD(const uint32 output[4])
     (output[3] /*EDX*/ == 0x444D4163);
 }
 
+static int Detect_MS_HyperV_AES ()
+{
+	int hasAesNI = 0;
+	// when Hyper-V is enabled on older versions of Windows Server (i.e. 2008 R2), the AES-NI capability 
+	// gets masked out for all applications, even running on the host.
+	// We try to detect Hyper-V virtual CPU and perform a dummy AES-NI operation to check its real presence
+	uint32 cpuid[4];
+	char HvProductName[13];
+
+	CpuId(0x40000000, cpuid);
+	memcpy (HvProductName, &cpuid[1], 12);
+	HvProductName[12] = 0;
+	if (_stricmp(HvProductName, "Microsoft Hv") == 0)
+	{
+#if defined (TC_WINDOWS_DRIVER) && !defined (_WIN64)
+		KFLOATING_SAVE floatingPointState;
+		if (NT_SUCCESS (KeSaveFloatingPointState (&floatingPointState)))
+		{
+#endif
+		__try
+		{
+			__m128i block, subkey, ciphered;
+			// perform AES round.
+			block = _mm_setr_epi32(0x11223344,0x55667788,0x99AABBCC,0xDDEEFF00);
+			subkey = _mm_setr_epi32(0xA5A5A5A5,0xA5A5A5A5,0x5A5A5A5A,0x5A5A5A5A);
+			ciphered = _mm_aesenc_si128(block, subkey);
+			hasAesNI = (ciphered.m128i_u64[0] == LL(0x2f4654b9485061fa) && ciphered.m128i_u64[1] == LL(0xc8b51f1fe1256f99));
+		}
+		__except (EXCEPTION_EXECUTE_HANDLER)
+		{
+			// ignore error if AES-NI not supported
+		}
+#if defined (TC_WINDOWS_DRIVER) && !defined (_WIN64)
+		KeRestoreFloatingPointState (&floatingPointState);
+		}
+#endif
+	}
+
+	return hasAesNI;
+}
+
 void DetectX86Features()
 {
 	uint32 cpuid[4], cpuid1[4];
@@ -215,40 +256,7 @@ void DetectX86Features()
 	// reference: http://artemonsecurity.com/vmde.pdf
 	if (!g_hasAESNI && (cpuid1[2] & (1<<31)))
 	{
-		// when Hyper-V is enabled on older versions of Windows Server (i.e. 2008 R2), the AES-NI capability 
-		// gets masked out for all applications, even running on the host.
-		// We try to detect Hyper-V virtual CPU and perform a dummy AES-NI operation to check its real presence
-		uint32 cpuid2[4];
-		char HvProductName[13];
-
-		CpuId(0x40000000, cpuid2);
-		memcpy (HvProductName, &cpuid2[1], 12);
-		HvProductName[12] = 0;
-		if (_stricmp(HvProductName, "Microsoft Hv") == 0)
-		{
-#if defined (TC_WINDOWS_DRIVER) && !defined (_WIN64)
-			KFLOATING_SAVE floatingPointState;
-			if (NT_SUCCESS (KeSaveFloatingPointState (&floatingPointState)))
-			{
-#endif
-			__try
-			{
-				__m128i block, subkey, ciphered;
-				// perform AES round.
-				block = _mm_setr_epi32(0x11223344,0x55667788,0x99AABBCC,0xDDEEFF00);
-				subkey = _mm_setr_epi32(0xA5A5A5A5,0xA5A5A5A5,0x5A5A5A5A,0x5A5A5A5A);
-				ciphered = _mm_aesenc_si128(block, subkey);
-				g_hasAESNI = (ciphered.m128i_u64[0] == LL(0x2f4654b9485061fa) && ciphered.m128i_u64[1] == LL(0xc8b51f1fe1256f99));
-			}
-			__except (EXCEPTION_EXECUTE_HANDLER)
-			{
-				// ignore error if AES-NI not supported
-			}
-#if defined (TC_WINDOWS_DRIVER) && !defined (_WIN64)
-			KeRestoreFloatingPointState (&floatingPointState);
-			}
-#endif
-		}
+		g_hasAESNI = Detect_MS_HyperV_AES ();
 	}
 #endif
 
@@ -282,4 +290,27 @@ void DetectX86Features()
 	*((volatile int*)&g_x86DetectionDone) = 1;
 }
 
+int is_aes_hw_cpu_supported ()
+{
+	int bHasAESNI = 0;
+	uint32 cpuid[4];
+
+	if (CpuId(1, cpuid))
+	{
+		if (cpuid[2] & (1<<25))
+			bHasAESNI = 1;
+#if (defined(__AES__) && defined(__PCLMUL__)) || defined(__INTEL_COMPILER) || CRYPTOPP_BOOL_AESNI_INTRINSICS_AVAILABLE
+		// Hypervisor = bit 31 of ECX of CPUID leaf 0x1
+		// reference: http://artemonsecurity.com/vmde.pdf
+		if (!bHasAESNI && (cpuid[2] & (1<<31)))
+		{
+			bHasAESNI = Detect_MS_HyperV_AES ();
+		}
+#endif
+	}
+
+	return bHasAESNI;
+}
+
 #endif
+
diff --git a/src/Volume/Cipher.cpp b/src/Volume/Cipher.cpp
index 743ef34c..a90b3c46 100644
--- a/src/Volume/Cipher.cpp
+++ b/src/Volume/Cipher.cpp
@@ -19,6 +19,7 @@
 
 #ifdef TC_AES_HW_CPU
 #	include "Crypto/Aes_hw_cpu.h"
+#	include "Crypto/cpu.h"
 #endif
 
 namespace VeraCrypt
@@ -181,7 +182,7 @@ namespace VeraCrypt
 
 		if (!stateValid)
 		{
-			state = is_aes_hw_cpu_supported() ? true : false;
+			state = g_hasAESNI ? true : false;
 			stateValid = true;
 		}
 		return state && HwSupportEnabled;