[Qemu-devel] [PATCH STABLE 2/3] Fix x86 feature modifications for features that set multiple bits

[Glauber Costa <glommer@redhat.com>]

From: Avi Kivity <avi@redhat.com>

QEMU allows adding or removing cpu features by using the syntax '-cpu +feature'
or '-cpu -feature'.  Some cpuid features cause more than one bit to be set or
cleared; but QEMU stops after just one bit has been modified, causing the
feature bits to be inconsistent.

Fix by allowing all feature bits corresponding to a given name to be set.

Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Signed-off-by: Glauber Costa <glommer@redhat.com>
---
 target-i386/helper.c |   13 ++++++++-----
 1 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/target-i386/helper.c b/target-i386/helper.c
index 3eb9697..1433857 100644
--- a/target-i386/helper.c
+++ b/target-i386/helper.c
@@ -66,28 +66,31 @@ static void add_flagname_to_bitmaps(char *flagname, uint32_t *features,
                                     uint32_t *ext3_features)
 {
     int i;
+    int found = 0;
 
     for ( i = 0 ; i < 32 ; i++ ) 
         if (feature_name[i] && !strcmp (flagname, feature_name[i])) {
             *features |= 1 << i;
-            return;
+            found = 1;
         }
     for ( i = 0 ; i < 32 ; i++ ) 
         if (ext_feature_name[i] && !strcmp (flagname, ext_feature_name[i])) {
             *ext_features |= 1 << i;
-            return;
+            found = 1;
         }
     for ( i = 0 ; i < 32 ; i++ ) 
         if (ext2_feature_name[i] && !strcmp (flagname, ext2_feature_name[i])) {
             *ext2_features |= 1 << i;
-            return;
+            found = 1;
         }
     for ( i = 0 ; i < 32 ; i++ ) 
         if (ext3_feature_name[i] && !strcmp (flagname, ext3_feature_name[i])) {
             *ext3_features |= 1 << i;
-            return;
+            found = 1;
         }
-    fprintf(stderr, "CPU feature %s not found\n", flagname);
+    if (!found) {
+        fprintf(stderr, "CPU feature %s not found\n", flagname);
+    }
 }
 
 typedef struct x86_def_t {
-- 
1.5.6.6