When the "migratable" property was implemented, the behavior was tested
by changing the default on the code, but actually using the option on
the command-line (e.g. "-cpu host,migratable=false") doesn't work as
expected. This is a regression for a common use case of "-cpu host",
which is to enable features that are supported by the host CPU + kernel
before feature-specific code is added to QEMU.
Fix this by initializing the feature words for "-cpu host" on
x86_cpu_parse_featurestr(), right after parsing the CPU options.
Signed-off-by: Eduardo Habkost <ehabk...@redhat.com>
---
I was considering a more complex (but less hacky) fix, by introducing an
enum FeatureBit { OFF, ON, HOST }, making FeatureWord a 32-element
FeatureBit array, and initializing the actual feature bits on
x86_cpu_realizefn(). But as this is a patch for qemu-stable, I kept the
fix as simple as possible.
---
target-i386/cpu-qom.h | 1 +
target-i386/cpu.c | 17 ++++++++++++-----
2 files changed, 13 insertions(+), 5 deletions(-)
diff --git a/target-i386/cpu-qom.h b/target-i386/cpu-qom.h
index 71a1b97..7755466 100644
--- a/target-i386/cpu-qom.h
+++ b/target-i386/cpu-qom.h
@@ -92,6 +92,7 @@ typedef struct X86CPU {
bool enforce_cpuid;
bool expose_kvm;
bool migratable;
+ bool host_features;
/* if true the CPUID code directly forward host cache leaves to the guest
*/
bool cache_info_passthrough;
diff --git a/target-i386/cpu.c b/target-i386/cpu.c
index 6d008ab..c0f8efc 100644
--- a/target-i386/cpu.c
+++ b/target-i386/cpu.c
@@ -1318,18 +1318,18 @@ static void host_x86_cpu_initfn(Object *obj)
X86CPU *cpu = X86_CPU(obj);
CPUX86State *env = &cpu->env;
KVMState *s = kvm_state;
- FeatureWord w;
assert(kvm_enabled());
+ /* We can't fill the features array here because we don't know yet if
+ * "migratable" is true or false.
+ */
+ cpu->host_features = true;
+
env->cpuid_level = kvm_arch_get_supported_cpuid(s, 0x0, 0, R_EAX);
env->cpuid_xlevel = kvm_arch_get_supported_cpuid(s, 0x80000000, 0, R_EAX);
env->cpuid_xlevel2 = kvm_arch_get_supported_cpuid(s, 0xC0000000, 0, R_EAX);
- for (w = 0; w < FEATURE_WORDS; w++) {
- env->features[w] =
- x86_cpu_get_supported_feature_word(w, cpu->migratable);
- }
object_property_set_bool(OBJECT(cpu), true, "pmu", &error_abort);
}
@@ -1828,6 +1828,13 @@ static void x86_cpu_parse_featurestr(CPUState *cs, char
*features,
featurestr = strtok(NULL, ",");
}
+ if (cpu->host_features) {
+ for (w = 0; w < FEATURE_WORDS; w++) {
+ env->features[w] =
+ x86_cpu_get_supported_feature_word(w, cpu->migratable);
+ }
+ }
+
for (w = 0; w < FEATURE_WORDS; w++) {
env->features[w] |= plus_features[w];
env->features[w] &= ~minus_features[w];
--
1.9.3
