Allow user to instrument cpuid instruction

qemu/target/i386/misc_helper.c

@@ -105,6 +105,7 @@ void helper_into(CPUX86State *env, int next_eip_addend)
 void helper_cpuid(CPUX86State *env)
 {
     uint32_t eax, ebx, ecx, edx;
+    struct hook *hook;
 
     cpu_svm_check_intercept_param(env, SVM_EXIT_CPUID, 0, GETPC());
 
@@ -114,6 +115,21 @@ void helper_cpuid(CPUX86State *env)
     env->regs[R_EBX] = ebx;
     env->regs[R_ECX] = ecx;
     env->regs[R_EDX] = edx;
+
+    // Unicorn: call registered CPUID hooks
+    HOOK_FOREACH_VAR_DECLARE;
+    HOOK_FOREACH(env->uc, hook, UC_HOOK_INSN) {
+        if (hook->to_delete)
+            continue;
+        if (!HOOK_BOUND_CHECK(hook, env->eip))
+            continue;
+        if (hook->insn == UC_X86_INS_CPUID)
+            ((uc_cb_insn_syscall_t)hook->callback)(env->uc, hook->user_data);
+
+        // the last callback may already asked to stop emulation
+        if (env->uc->stop_request)
+            break;
+    }
 }
 
 target_ulong helper_read_crN(CPUX86State *env, int reg)

qemu/target/i386/unicorn.c

@@ -1564,7 +1564,8 @@ static bool x86_insn_hook_validate(uint32_t insn_enum)
     if (insn_enum != UC_X86_INS_IN
         &&  insn_enum != UC_X86_INS_OUT
         &&  insn_enum != UC_X86_INS_SYSCALL
-        &&  insn_enum != UC_X86_INS_SYSENTER) {
+        &&  insn_enum != UC_X86_INS_SYSENTER
+        &&  insn_enum != UC_X86_INS_CPUID) {
         return false;
     }
     return true;

tests/unit/test_x86.c

@@ -525,6 +525,31 @@ static void test_x86_sysenter() {
     OK(uc_close(uc));
 }
 
+static void test_x86_hook_cpuid_callback(uc_engine* uc, void* data) {
+    int reg = 7;
+
+    OK(uc_reg_write(uc, UC_X86_REG_EAX, &reg));
+}
+
+static void test_x86_hook_cpuid() {
+    uc_engine* uc;
+    char code[] = "\x40\x0F\xA2"; // INC EAX; CPUID
+    uc_hook h;
+    int reg;
+
+    uc_common_setup(&uc, UC_ARCH_X86, UC_MODE_32, code, sizeof(code) - 1);
+
+    OK(uc_hook_add(uc, &h, UC_HOOK_INSN, test_x86_hook_cpuid_callback, NULL, 1, 0, UC_X86_INS_CPUID));
+
+    OK(uc_emu_start(uc, code_start, code_start + sizeof(code) - 1, 0, 0));
+
+    OK(uc_reg_read(uc, UC_X86_REG_EAX, &reg));
+
+    TEST_CHECK(reg == 7);
+
+    OK(uc_close(uc));
+}
+
 TEST_LIST = {
     { "test_x86_in", test_x86_in },
     { "test_x86_out", test_x86_out },
@@ -545,5 +570,6 @@ TEST_LIST = {
     { "test_x86_smc_xor", test_x86_smc_xor},
     { "test_x86_mmio_uc_mem_rw", test_x86_mmio_uc_mem_rw},
     { "test_x86_sysenter", test_x86_sysenter},
+    { "test_x86_hook_cpuid", test_x86_hook_cpuid},
     { NULL, NULL }
 };