commit e265e3e48049fbece9eaf536aa00ca41aa3c54d0
author Eduardo Habkost <ehabkost@redhat.com> Wed Sep 02 11:19:11 2015 -0300
committer Eduardo Habkost <ehabkost@redhat.com> Fri Oct 23 12:59:27 2015 -0200
tree 8012ed63530393207b4ba9c9fcbf4e74d9957713
parent dd75d4fcb4a82c34d4f466e7fc166162b71ff740

target-i386: Disable cache info passthrough by default

The host cache information may not make sense for the guest if the VM
CPU topology doesn't match the host CPU topology. To make sure we won't
expose broken cache information to the guest, disable cache info
passthrough by default, and add a new "host-cache-info" property that
can be used to enable the old behavior for users that really need it.

Cc: Benoît Canet <benoit@irqsave.net>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>

include/hw/i386/pc.h

diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
index c5961d7..7037de0 100644
--- a/include/hw/i386/pc.h
+++ b/include/hw/i386/pc.h
@@ -318,6 +318,11 @@
             .driver   = "Broadwell-noTSX-" TYPE_X86_CPU,\
             .property = "abm",\
             .value    = "off",\
+        },\
+        {\
+            .driver   = "host" "-" TYPE_X86_CPU,\
+            .property = "host-cache-info",\
+            .value    = "on",\
         },
 
 #define PC_COMPAT_2_3 \

target-i386/cpu.c

diff --git a/target-i386/cpu.c b/target-i386/cpu.c
index 5f53af2..987253d 100644
--- a/target-i386/cpu.c
+++ b/target-i386/cpu.c
@@ -656,7 +656,6 @@
     int stepping;
     FeatureWordArray features;
     char model_id[48];
-    bool cache_info_passthrough;
 };
 
 static X86CPUDefinition builtin_x86_defs[] = {
@@ -1420,6 +1419,7 @@
 
 static Property host_x86_cpu_properties[] = {
     DEFINE_PROP_BOOL("migratable", X86CPU, migratable, true),
+    DEFINE_PROP_BOOL("host-cache-info", X86CPU, cache_info_passthrough, false),
     DEFINE_PROP_END_OF_LIST()
 };
 
@@ -1446,7 +1446,6 @@
     cpu_x86_fill_model_id(host_cpudef.model_id);
 
     xcc->cpu_def = &host_cpudef;
-    host_cpudef.cache_info_passthrough = true;
 
     /* level, xlevel, xlevel2, and the feature words are initialized on
      * instance_init, because they require KVM to be initialized.
@@ -2094,7 +2093,6 @@
     object_property_set_int(OBJECT(cpu), def->stepping, "stepping", errp);
     object_property_set_int(OBJECT(cpu), def->xlevel, "xlevel", errp);
     object_property_set_int(OBJECT(cpu), def->xlevel2, "xlevel2", errp);
-    cpu->cache_info_passthrough = def->cache_info_passthrough;
     object_property_set_str(OBJECT(cpu), def->model_id, "model-id", errp);
     for (w = 0; w < FEATURE_WORDS; w++) {
         env->features[w] = def->features[w];