On Mon, Nov 02, 2015 at 05:26:42PM +0800, Haozhong Zhang wrote:
> The value of the migrated vcpu's TSC rate is determined as below.
> 1. If a TSC rate is specified by the cpu option 'tsc-freq', then this
> user-specified value will be used.
> 2. If neither a user-specified TSC rate nor a migrated TSC rate is
> present, we will use the TSC rate from KVM (returned by
> KVM_GET_TSC_KHZ).
> 3. Otherwise, we will use the migrated TSC rate.
>
> Signed-off-by: Haozhong Zhang <haozhong.zhang@xxxxxxxxx>
[...]
> diff --git a/target-i386/kvm.c b/target-i386/kvm.c
> index 64046cb..aae5e58 100644
> --- a/target-i386/kvm.c
> +++ b/target-i386/kvm.c
> @@ -3034,3 +3034,36 @@ int kvm_arch_msi_data_to_gsi(uint32_t data)
> {
> abort();
> }
> +
> +int kvm_arch_setup_tsc_khz(CPUState *cs)
> +{
> + X86CPU *cpu = X86_CPU(cs);
> + CPUX86State *env = &cpu->env;
> + int r;
> +
> + /*
> + * Prepare vcpu's TSC rate to be migrated.
> + *
> + * - If the user specifies the TSC rate by cpu option 'tsc-freq',
> + * we will use the user-specified value.
> + *
> + * - If there is neither user-specified TSC rate nor migrated TSC
> + * rate, we will ask KVM for the TSC rate by calling
> + * KVM_GET_TSC_KHZ.
> + *
> + * - Otherwise, if there is a migrated TSC rate, we will use the
> + * migrated value.
> + */
> + if (env->tsc_khz) {
> + env->tsc_khz_saved = env->tsc_khz;
> + } else if (!env->tsc_khz_saved) {
> + r = kvm_vcpu_ioctl(cs, KVM_GET_TSC_KHZ);
> + if (r < 0) {
> + fprintf(stderr, "KVM_GET_TSC_KHZ failed\n");
> + return r;
> + }
The lack of KVM_CAP_GET_TSC_KHZ should make QEMU abort, unless the user
is explicitly requesting a more strict mode where the TSC frequency will
be guaranteed to never change.
> + env->tsc_khz_saved = r;
> + }
Why do you need a separate tsc_khz_saved field, and don't simply use
tsc_khz? It would have the additional feature of letting QMP clients
query the current TSC rate by asking for the tsc-freq property on CPU
objects.
> +
> + return 0;
> +}
--
Eduardo
--
To unsubscribe from this list: send the line "unsubscribe kvm" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
