target/i386: TCG supports WBNOINVD

WBNOINVD is the same as INVD or WBINVD as far as TCG is concerned,
since there is no cache in TCG and therefore no invalidation side effect
in WBNOINVD.

With respect to SVM emulation, processors that do not support WBNOINVD
will ignore the prefix and treat it as WBINVD, while those that support
it will generate exactly the same vmexit.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

target/i386/cpu.c

@@ -678,7 +678,8 @@ void x86_cpu_vendor_words2str(char *dst, uint32_t vendor1,
 #define TCG_SGX_12_0_EBX_FEATURES 0
 #define TCG_SGX_12_1_EAX_FEATURES 0
 
-#define TCG_8000_0008_EBX  CPUID_8000_0008_EBX_XSAVEERPTR
+#define TCG_8000_0008_EBX  (CPUID_8000_0008_EBX_XSAVEERPTR | \
+          CPUID_8000_0008_EBX_WBNOINVD)
 
 FeatureWordInfo feature_word_info[FEATURE_WORDS] = {
     [FEAT_1_EDX] = {

target/i386/tcg/translate.c

@@ -6125,7 +6125,7 @@ static bool disas_insn(DisasContext *s, CPUState *cpu)
         break;
 
     case 0x108: /* invd */
-    case 0x109: /* wbinvd */
+    case 0x109: /* wbinvd; wbnoinvd with REPZ prefix */
         if (check_cpl0(s)) {
             gen_svm_check_intercept(s, (b & 1) ? SVM_EXIT_WBINVD : SVM_EXIT_INVD);
             /* nothing to do */