Merge openenclave#4302

4302: Set max cpuid input value to highest emulated value r=mingweishih a=thomasten cpuid(0) and cpuid(0x80000000) should return the highest emulated value instead of the CPU's actual value. This prevents some existing code to try higher leaves. Co-authored-by: Thomas Tendyck <[email protected]>
samuel-lee-msft · Nov 10, 2021 · 2faa98a · 2faa98a
2 parents dee3c1c + f16b7c3
commit 2faa98a
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Showing 3 changed files with 19 additions and 2 deletions.
diff --git a/enclave/core/sgx/cpuid.c b/enclave/core/sgx/cpuid.c
@@ -36,6 +36,12 @@ oe_result_t oe_initialize_cpuid(void)
     if (!(_cpuid_table[1][OE_CPUID_RCX] & OE_CPUID_AESNI_FEATURE))
         oe_abort();
 
+    // set max input value for basic and extended
+    _cpuid_table[oe_get_emulated_cpuid_leaf_index(0)][OE_CPUID_RAX] =
+        OE_CPUID_MAX_BASIC;
+    _cpuid_table[oe_get_emulated_cpuid_leaf_index(0x80000000)][OE_CPUID_RAX] =
+        OE_CPUID_MAX_EXTENDED;
+
     result = OE_OK;
 
 done:

diff --git a/include/openenclave/internal/cpuid.h b/include/openenclave/internal/cpuid.h
@@ -9,6 +9,8 @@
 
 #define OE_CPUID_OPCODE 0xA20F
 #define OE_CPUID_LEAF_COUNT 6 /* 0,1,4,7,0x80000000,0x80000001 */
+#define OE_CPUID_MAX_BASIC 7
+#define OE_CPUID_MAX_EXTENDED 0x80000001
 
 #define OE_CPUID_RAX 0
 #define OE_CPUID_RBX 1

diff --git a/tests/VectorException/host/host.c b/tests/VectorException/host/host.c
@@ -121,9 +121,13 @@ void test_sigill_handling(
 
         for (uint32_t j = 0; j < OE_CPUID_REG_COUNT; j++)
         {
-            if (i == 1 && j == 1)
+            if (leaf == 0 && j == OE_CPUID_RAX)
+            {
+                // The enclave sets this to the highest emulated leaf.
+                OE_TEST(OE_CPUID_MAX_BASIC == cpuid_table[i][j]);
+            }
+            else if (leaf == 1 && j == OE_CPUID_RBX)
             {
-                // Leaf 1. EBX register.
                 // The highest 8 bits indicates the current executing processor
                 // id.
                 // There is no guarantee that the value is the same across
@@ -135,6 +139,11 @@ void test_sigill_handling(
                     (cpuid_info[j] & 0x00FFFFFF) ==
                     (cpuid_table[i][j] & 0x00FFFFFF));
             }
+            else if (leaf == 0x80000000 && j == OE_CPUID_RAX)
+            {
+                // The enclave sets this to the highest emulated leaf.
+                OE_TEST(OE_CPUID_MAX_EXTENDED == cpuid_table[i][j]);
+            }
             else
             {
                 OE_TEST(cpuid_info[j] == cpuid_table[i][j]);