kvm: expose tsc deadline timer feature to guest

This patch exposes tsc deadline timer feature to guest if
1). in-kernel irqchip is used, and
2). kvm has emulated tsc deadline timer, and
3). user authorize the feature exposing via -cpu or +/- tsc-deadline

Signed-off-by: Liu, Jinsong <jinsong.liu@intel.com>
Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>
Acked-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
diff --git a/target-i386/cpu.h b/target-i386/cpu.h
index f257c97..33d221e 100644
--- a/target-i386/cpu.h
+++ b/target-i386/cpu.h
@@ -400,6 +400,7 @@
 #define CPUID_EXT_X2APIC   (1 << 21)
 #define CPUID_EXT_MOVBE    (1 << 22)
 #define CPUID_EXT_POPCNT   (1 << 23)
+#define CPUID_EXT_TSC_DEADLINE_TIMER (1 << 24)
 #define CPUID_EXT_XSAVE    (1 << 26)
 #define CPUID_EXT_OSXSAVE  (1 << 27)
 #define CPUID_EXT_HYPERVISOR  (1 << 31)
diff --git a/target-i386/kvm.c b/target-i386/kvm.c
index 0d0d8f6..52b577f 100644
--- a/target-i386/kvm.c
+++ b/target-i386/kvm.c
@@ -361,8 +361,13 @@
     env->cpuid_features &= kvm_arch_get_supported_cpuid(s, 1, 0, R_EDX);
 
     i = env->cpuid_ext_features & CPUID_EXT_HYPERVISOR;
+    j = env->cpuid_ext_features & CPUID_EXT_TSC_DEADLINE_TIMER;
     env->cpuid_ext_features &= kvm_arch_get_supported_cpuid(s, 1, 0, R_ECX);
     env->cpuid_ext_features |= i;
+    if (j && kvm_irqchip_in_kernel() &&
+        kvm_check_extension(s, KVM_CAP_TSC_DEADLINE_TIMER)) {
+        env->cpuid_ext_features |= CPUID_EXT_TSC_DEADLINE_TIMER;
+    }
 
     env->cpuid_ext2_features &= kvm_arch_get_supported_cpuid(s, 0x80000001,
                                                              0, R_EDX);