[Qemu-devel] [PATCH v4 1/2] target-i386: fallback vcpu's TSC rate to value returned by KVM

[Haozhong Zhang <haozhong.zhang@intel.com>]

If no user-specified TSC rate is present, we will try to set
env->tsc_khz to the value returned by KVM_GET_TSC_KHZ.

Signed-off-by: Haozhong Zhang <haozhong.zhang@intel.com>
---
 target-i386/kvm.c | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/target-i386/kvm.c b/target-i386/kvm.c
index 2a9953b..9084b29 100644
--- a/target-i386/kvm.c
+++ b/target-i386/kvm.c
@@ -2327,6 +2327,27 @@ static int kvm_get_debugregs(X86CPU *cpu)
     return 0;
 }
 
+static void kvm_arch_set_tsc_khz(CPUState *cs)
+{
+    X86CPU *cpu = X86_CPU(cs);
+    CPUX86State *env = &cpu->env;
+    int r;
+
+    /*
+     * If no user-specified TSC frequency is present, we will try to
+     * set env->tsc_khz to the value used by KVM.
+     */
+    if (!env->tsc_khz) {
+        r = kvm_check_extension(cs->kvm_state, KVM_CAP_GET_TSC_KHZ) ?
+            kvm_vcpu_ioctl(cs, KVM_GET_TSC_KHZ) : -ENOTSUP;
+        if (r < 0) {
+            error_report("warning: KVM_GET_TSC_KHZ failed");
+        } else {
+            env->tsc_khz = r;
+        }
+    }
+}
+
 int kvm_arch_put_registers(CPUState *cpu, int level)
 {
     X86CPU *x86_cpu = X86_CPU(cpu);
@@ -2341,6 +2362,10 @@ int kvm_arch_put_registers(CPUState *cpu, int level)
         }
     }
 
+    if (level == KVM_PUT_FULL_STATE) {
+        kvm_arch_set_tsc_khz(cpu);
+    }
+
     ret = kvm_getput_regs(x86_cpu, 1);
     if (ret < 0) {
         return ret;
-- 
2.4.8