On Mon, Nov 16, 2015 at 04:04:07PM +0800, Haozhong Zhang wrote:
> 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@xxxxxxxxx>
> ---
> 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;
Can't we do this on kvm_arch_init_vcpu()? kvm_arch_put_registers()'s purpose is
to just copy data from QEMU to KVM, not the other way around.
> + if (r < 0) {
> + error_report("warning: KVM_GET_TSC_KHZ failed");
Having a kernel that doesn't support KVM_CAP_GET_TSC_KHZ shouldn't trigger a
warning every time we run QEMU, unless the user is explicitly asking for a
feature that requires KVM_GET_TSC_KHZ.
> + } 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);
> + }
I see that kvm_arch_set_tsc_khz() will be extended to call
KVM_SET_TSC_KHZ in the next patch, so the kvm_arch_set_tsc_khz()
seems to belong here. But the KVM_GET_TSC_KHZ call doesn't seem
to belong in kvm_arch_set_tsc_khz()
kvm_arch_put_registers() callers don't expect any QEMU-side data
to change, but just that KVM data is updated according to the
QEMU-side data.
> +
> ret = kvm_getput_regs(x86_cpu, 1);
> if (ret < 0) {
> return ret;
> --
> 2.4.8
>
--
Eduardo
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