qemu/target-i386-handle-filtered_features-in-a-new-functi.patch

From b9d29966103ca671718ef1eb5b68067b05fad340 Mon Sep 17 00:00:00 2001
From: Paolo Bonzini <pbonzini@redhat.com>
Date: Tue, 2 Jul 2019 15:32:41 +0200
Subject: [PATCH] target/i386: handle filtered_features in a new function
 mark_unavailable_features

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 optionally reporting them.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 target/i386/cpu.c | 87 ++++++++++++++++++++++++++---------------------
 1 file changed, 48 insertions(+), 39 deletions(-)

diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index e65f372f25..8798cafc7a 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -3216,17 +3216,41 @@ 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 < FEATURE_WORDS; w++) {
+        if (cpu->filtered_features[w]) {
+            return true;
+        }
+    }
+
+    return false;
+}
+
+static void mark_unavailable_features(X86CPU *cpu, FeatureWord w, uint32_t mask,
+                                      const char *verbose_prefix)
+{
+    CPUX86State *env = &cpu->env;
     FeatureWordInfo *f = &feature_word_info[w];
     int i;
     char *feat_word_str;
 
+    if (!cpu->force_features) {
+        env->features[w] &= ~mask;
+    }
+    cpu->filtered_features[w] |= mask;
+
+    if (!verbose_prefix) {
+        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]",
+                        verbose_prefix,
                         feat_word_str,
                         f->feat_names[i] ? "." : "",
                         f->feat_names[i] ? f->feat_names[i] : "", i);
@@ -3631,7 +3655,7 @@ 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, bool verbose);
 
 /* Build a list with the name of all features on a feature word array */
 static void x86_cpu_list_feature_names(FeatureWordArray features,
@@ -3696,7 +3720,7 @@ static void x86_cpu_class_check_missing_features(X86CPUClass *xcc,
         next = &new->next;
     }
 
-    x86_cpu_filter_features(xc);
+    x86_cpu_filter_features(xc, false);
 
     x86_cpu_list_feature_names(xc->filtered_features, next);
 
@@ -3904,15 +3928,6 @@ 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;
@@ -5274,24 +5289,24 @@ 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, bool verbose)
 {
     CPUX86State *env = &cpu->env;
     FeatureWord w;
-    int rv = 0;
+    const char *prefix = NULL;
+
+    if (verbose) {
+        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];
-        uint32_t available_features = requested_features & host_feat;
-        if (!cpu->force_features) {
-            env->features[w] = available_features;
-        }
-        cpu->filtered_features[w] = requested_features & ~available_features;
-        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) &&
@@ -5317,13 +5332,9 @@ 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)
@@ -5364,16 +5375,14 @@ 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, cpu->check_cpuid || cpu->enforce_cpuid);
+
+    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
-- 
2.27.0