target/i386: define md-clear bit

md-clear is a new CPUID bit which is set when microcode provides the
mechanism to invoke a flush of various exploitable CPU buffers by invoking
the VERW instruction.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20190515141011.5315-2-berrange@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>

target/i386/cpu.c

@@ -1077,7 +1077,7 @@ static FeatureWordInfo feature_word_info[FEATURE_WORDS] = {
         .feat_names = {
             NULL, NULL, "avx512-4vnniw", "avx512-4fmaps",
             NULL, NULL, NULL, NULL,
-            NULL, NULL, NULL, NULL,
+            NULL, NULL, "md-clear", NULL,
             NULL, NULL, NULL, NULL,
             NULL, NULL, NULL, NULL,
             NULL, NULL, NULL, NULL,