target/i386: add fast short REP MOV support

For CPUs support fast short REP MOV[CPUID.(EAX=7,ECX=0):EDX(bit4)], e.g
Icelake and Tigerlake, expose it to the guest VM.
Reviewed-by: NEduardo Habkost <ehabkost@redhat.com>
Signed-off-by: NChenyi Qiang <chenyi.qiang@intel.com>
Message-Id: <20200714084148.26690-2-chenyi.qiang@intel.com>
Signed-off-by: NEduardo Habkost <ehabkost@redhat.com>

target/i386/cpu.c

@@ -984,7 +984,7 @@ static FeatureWordInfo feature_word_info[FEATURE_WORDS] = {
         .type = CPUID_FEATURE_WORD,
         .feat_names = {
             NULL, NULL, "avx512-4vnniw", "avx512-4fmaps",
-            NULL, NULL, NULL, NULL,
+            "fsrm", NULL, NULL, NULL,
             "avx512-vp2intersect", NULL, "md-clear", NULL,
             NULL, NULL, "serialize", NULL,
             "tsx-ldtrk", NULL, NULL /* pconfig */, NULL,

target/i386/cpu.h

@@ -775,6 +775,8 @@ typedef uint64_t FeatureWordArray[FEATURE_WORDS];
 #define CPUID_7_0_EDX_AVX512_4VNNIW     (1U << 2)
 /* AVX512 Multiply Accumulation Single Precision */
 #define CPUID_7_0_EDX_AVX512_4FMAPS     (1U << 3)
+/* Fast Short Rep Mov */
+#define CPUID_7_0_EDX_FSRM              (1U << 4)
 /* AVX512 Vector Pair Intersection to a Pair of Mask Registers */
 #define CPUID_7_0_EDX_AVX512_VP2INTERSECT (1U << 8)
 /* SERIALIZE instruction */