[Qemu-devel] [PATCH 1/7] target/i386: handle filtered_features in a new function mark_unavailable_features

[Paolo Bonzini <pbonzini@redhat.com>]

The next patch will add a different reason for filtering features, unrelated
to host feature support.  Extract a new function that takes care of disabling
the features and reporting them.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 target/i386/cpu.c | 76 ++++++++++++++++++++++++++++++-------------------------
 1 file changed, 41 insertions(+), 35 deletions(-)

diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index da6eb67..9149d0d 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -3236,17 +3236,39 @@ static char *feature_word_description(FeatureWordInfo *f, uint32_t bit)
     return NULL;
 }
 
-static void report_unavailable_features(FeatureWord w, uint32_t mask)
+static bool x86_cpu_have_filtered_features(X86CPU *cpu)
 {
+    FeatureWord w;
+
+    for (w = 0; w < ARRAY_SIZE(feature_word_info); w++) {
+         if (cpu->filtered_features[w]) {
+             return true;
+         }
+    }
+
+    return false;
+}
+
+static void mark_unavailable_features(X86CPU *cpu, FeatureWord w, uint32_t mask,
+                                      const char *prefix)
+{
+    CPUX86State *env = &cpu->env;
     FeatureWordInfo *f = &feature_word_info[w];
     int i;
     char *feat_word_str;
 
+    env->features[w] &= ~mask;
+    cpu->filtered_features[w] |= mask;
+
+    if (!cpu->check_cpuid && !cpu->enforce_cpuid) {
+        return;
+    }
+
     for (i = 0; i < 32; ++i) {
         if ((1UL << i) & mask) {
             feat_word_str = feature_word_description(f, i);
-            warn_report("%s doesn't support requested feature: %s%s%s [bit %d]",
-                        accel_uses_host_cpuid() ? "host" : "TCG",
+            warn_report("%s: %s%s%s [bit %d]",
+                        prefix,
                         feat_word_str,
                         f->feat_names[i] ? "." : "",
                         f->feat_names[i] ? f->feat_names[i] : "", i);
@@ -3691,7 +3713,7 @@ static void x86_cpu_parse_featurestr(const char *typename, char *features,
 }
 
 static void x86_cpu_expand_features(X86CPU *cpu, Error **errp);
-static int x86_cpu_filter_features(X86CPU *cpu);
+static void x86_cpu_filter_features(X86CPU *cpu);
 
 /* Build a list with the name of all features on a feature word array */
 static void x86_cpu_list_feature_names(FeatureWordArray features,
@@ -3923,15 +3945,6 @@ static uint32_t x86_cpu_get_supported_feature_word(FeatureWord w,
     return r;
 }
 
-static void x86_cpu_report_filtered_features(X86CPU *cpu)
-{
-    FeatureWord w;
-
-    for (w = 0; w < FEATURE_WORDS; w++) {
-        report_unavailable_features(w, cpu->filtered_features[w]);
-    }
-}
-
 static void x86_cpu_apply_props(X86CPU *cpu, PropValue *props)
 {
     PropValue *pv;
@@ -5170,21 +5183,20 @@ out:
  *
  * Returns: 0 if all flags are supported by the host, non-zero otherwise.
  */
-static int x86_cpu_filter_features(X86CPU *cpu)
+static void x86_cpu_filter_features(X86CPU *cpu)
 {
     CPUX86State *env = &cpu->env;
     FeatureWord w;
-    int rv = 0;
+    const char *prefix = accel_uses_host_cpuid()
+                         ? "host doesn't support requested feature"
+                         : "TCG doesn't support requested feature";
 
     for (w = 0; w < FEATURE_WORDS; w++) {
         uint32_t host_feat =
             x86_cpu_get_supported_feature_word(w, false);
         uint32_t requested_features = env->features[w];
-        env->features[w] &= host_feat;
-        cpu->filtered_features[w] = requested_features & ~env->features[w];
-        if (cpu->filtered_features[w]) {
-            rv = 1;
-        }
+        uint32_t unavailable_features = requested_features & ~host_feat;
+        mark_unavailable_features(cpu, w, unavailable_features, prefix);
     }
 
     if ((env->features[FEAT_7_0_EBX] & CPUID_7_0_EBX_INTEL_PT) &&
@@ -5210,13 +5222,9 @@ static int x86_cpu_filter_features(X86CPU *cpu)
              * host can't emulate the capabilities we report on
              * cpu_x86_cpuid(), intel-pt can't be enabled on the current host.
              */
-            env->features[FEAT_7_0_EBX] &= ~CPUID_7_0_EBX_INTEL_PT;
-            cpu->filtered_features[FEAT_7_0_EBX] |= CPUID_7_0_EBX_INTEL_PT;
-            rv = 1;
+            mark_unavailable_features(cpu, FEAT_7_0_EBX, CPUID_7_0_EBX_INTEL_PT, prefix);
         }
     }
-
-    return rv;
 }
 
 static void x86_cpu_realizefn(DeviceState *dev, Error **errp)
@@ -5257,16 +5265,14 @@ static void x86_cpu_realizefn(DeviceState *dev, Error **errp)
         goto out;
     }
 
-    if (x86_cpu_filter_features(cpu) &&
-        (cpu->check_cpuid || cpu->enforce_cpuid)) {
-        x86_cpu_report_filtered_features(cpu);
-        if (cpu->enforce_cpuid) {
-            error_setg(&local_err,
-                       accel_uses_host_cpuid() ?
-                           "Host doesn't support requested features" :
-                           "TCG doesn't support requested features");
-            goto out;
-        }
+    x86_cpu_filter_features(cpu);
+
+    if (cpu->enforce_cpuid && x86_cpu_have_filtered_features(cpu)) {
+        error_setg(&local_err,
+                   accel_uses_host_cpuid() ?
+                       "Host doesn't support requested features" :
+                       "TCG doesn't support requested features");
+        goto out;
     }
 
     /* On AMD CPUs, some CPUID[8000_0001].EDX bits must match the bits on
-- 
1.8.3.1