[Qemu-devel] [PATCH 2/2] expose kvm pv features

[Glauber Costa <glommer@redhat.com>]

expose kvm paravirtual features into cpuid. This enables
the use of kvmclock in qemu guests. (and all the other
features too).

Signed-off-by: Glauber Costa <glommer@redhat.com>
---
 kvm.h             |    5 +++++
 target-i386/kvm.c |   29 +++++++++++++++++++++++++++++
 2 files changed, 34 insertions(+), 0 deletions(-)

diff --git a/kvm.h b/kvm.h
index efce145..49a2653 100644
--- a/kvm.h
+++ b/kvm.h
@@ -17,6 +17,8 @@
 #include "config.h"
 
 #ifdef CONFIG_KVM
+#include <linux/kvm.h>
+#include <linux/kvm_para.h>
 extern int kvm_allowed;
 
 #define kvm_enabled() (kvm_allowed)
@@ -76,4 +78,7 @@ int kvm_arch_init(KVMState *s, int smp_cpus);
 
 int kvm_arch_init_vcpu(CPUState *env);
 
+/* x86 specific */
+uint32_t kvm_get_para_features(CPUState *env);
+
 #endif
diff --git a/target-i386/kvm.c b/target-i386/kvm.c
index 4a55931..736ee38 100644
--- a/target-i386/kvm.c
+++ b/target-i386/kvm.c
@@ -33,6 +33,33 @@
     do { } while (0)
 #endif
 
+static struct kvm_para_features {
+    int cap;
+    int feature;
+} para_features[] = {
+#ifdef KVM_CAP_CLOCKSOURCE
+       { KVM_CAP_CLOCKSOURCE, KVM_FEATURE_CLOCKSOURCE },
+#endif
+#ifdef KVM_CAP_NOP_IO_DELAY
+       { KVM_CAP_NOP_IO_DELAY, KVM_FEATURE_NOP_IO_DELAY },
+#endif
+#ifdef KVM_CAP_PV_MMU
+       { KVM_CAP_PV_MMU, KVM_FEATURE_MMU_OP },
+#endif
+};
+
+uint32_t kvm_get_para_features(CPUState *env)
+ {
+    uint32_t i, features = 0;
+
+    for (i = 0; i < ARRAY_SIZE(para_features); i++) {
+        if (kvm_ioctl(env->kvm_state, KVM_CHECK_EXTENSION, para_features[i].cap))
+            features |= (1 << para_features[i].feature);
+    }
+
+    return features;
+}
+
 typedef struct {
     struct kvm_cpuid cpuid;
     struct kvm_cpuid_entry entries[100];
@@ -69,6 +96,8 @@ int kvm_arch_init_vcpu(CPUState *env)
 
     kvm_fill_cpuid(env, &cpuid_data, 0, limit);
 
+    kvm_fill_cpuid(env, &cpuid_data, KVM_CPUID_SIGNATURE, KVM_CPUID_FEATURES);
+
     cpu_x86_cpuid(env, 0x80000000, &eax, &ebx, &ecx, &edx);
     limit = eax;
     kvm_fill_cpuid(env, &cpuid_data, 0x80000000, limit);
-- 
1.5.6.5