On Mon, Nov 16, 2015 at 04:04:08PM +0800, Haozhong Zhang wrote:
> This patch enables migrating vcpu's TSC rate. If KVM on the destination
> machine supports TSC scaling, guest programs will observe a consistent
> TSC rate across the migration.
>
> If TSC scaling is not supported on the destination machine, the
> migration will not be aborted and QEMU on the destination will not set
> vcpu's TSC rate to the migrated value.
>
> If vcpu's TSC rate specified by CPU option 'tsc-freq' on the destination
> machine is inconsistent with the migrated TSC rate, the migration will
> be aborted.
>
> For backwards compatibility, the migration of vcpu's TSC rate is
> disabled on pc-*-2.4 and older machine types.
>
> Signed-off-by: Haozhong Zhang <haozhong.zhang@xxxxxxxxx>
> ---
> hw/i386/pc.c | 1 +
> hw/i386/pc_piix.c | 1 +
> hw/i386/pc_q35.c | 1 +
> include/hw/i386/pc.h | 1 +
> target-i386/cpu.c | 2 +-
> target-i386/cpu.h | 1 +
> target-i386/kvm.c | 26 ++++++++++++++++++++++++--
> target-i386/machine.c | 28 ++++++++++++++++++++++++++++
> 8 files changed, 58 insertions(+), 3 deletions(-)
>
> diff --git a/hw/i386/pc.c b/hw/i386/pc.c
> index 0cb8afd..2f2fc93 100644
> --- a/hw/i386/pc.c
> +++ b/hw/i386/pc.c
> @@ -1952,6 +1952,7 @@ static void pc_machine_class_init(ObjectClass *oc, void *data)
> HotplugHandlerClass *hc = HOTPLUG_HANDLER_CLASS(oc);
>
> pcmc->get_hotplug_handler = mc->get_hotplug_handler;
> + pcmc->save_tsc_khz = true;
> mc->get_hotplug_handler = pc_get_hotpug_handler;
> mc->cpu_index_to_socket_id = pc_cpu_index_to_socket_id;
> mc->default_boot_order = "cad";
> diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
> index 07d0baa..7c5b0d2 100644
> --- a/hw/i386/pc_piix.c
> +++ b/hw/i386/pc_piix.c
> @@ -489,6 +489,7 @@ static void pc_i440fx_2_4_machine_options(MachineClass *m)
> m->alias = NULL;
> m->is_default = 0;
> pcmc->broken_reserved_end = true;
> + pcmc->save_tsc_khz = false;
> SET_MACHINE_COMPAT(m, PC_COMPAT_2_4);
> }
>
> diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c
> index 0fdae09..fd8efe3 100644
> --- a/hw/i386/pc_q35.c
> +++ b/hw/i386/pc_q35.c
> @@ -387,6 +387,7 @@ static void pc_q35_2_4_machine_options(MachineClass *m)
> m->hw_version = "2.4.0";
> m->alias = NULL;
> pcmc->broken_reserved_end = true;
> + pcmc->save_tsc_khz = false;
> SET_MACHINE_COMPAT(m, PC_COMPAT_2_4);
> }
>
> diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
> index 4bbc0ff..fea0f28 100644
> --- a/include/hw/i386/pc.h
> +++ b/include/hw/i386/pc.h
> @@ -60,6 +60,7 @@ struct PCMachineClass {
>
> /*< public >*/
> bool broken_reserved_end;
> + bool save_tsc_khz;
> HotplugHandler *(*get_hotplug_handler)(MachineState *machine,
> DeviceState *dev);
> };
> diff --git a/target-i386/cpu.c b/target-i386/cpu.c
> index e5f1c5b..98c6a4c 100644
> --- a/target-i386/cpu.c
> +++ b/target-i386/cpu.c
> @@ -1724,7 +1724,7 @@ static void x86_cpuid_set_tsc_freq(Object *obj, Visitor *v, void *opaque,
> return;
> }
>
> - cpu->env.tsc_khz = value / 1000;
> + cpu->env.tsc_khz = cpu->env.user_tsc_khz = value / 1000;
> }
>
> static void x86_cpuid_get_apic_id(Object *obj, Visitor *v, void *opaque,
> diff --git a/target-i386/cpu.h b/target-i386/cpu.h
> index fc4a605..1ad1da8 100644
> --- a/target-i386/cpu.h
> +++ b/target-i386/cpu.h
> @@ -973,6 +973,7 @@ typedef struct CPUX86State {
> uint32_t sipi_vector;
> bool tsc_valid;
> int64_t tsc_khz;
> + int64_t user_tsc_khz;
> void *kvm_xsave_buf;
>
> uint64_t mcg_cap;
> diff --git a/target-i386/kvm.c b/target-i386/kvm.c
> index 9084b29..8448248 100644
> --- a/target-i386/kvm.c
> +++ b/target-i386/kvm.c
> @@ -2334,8 +2334,30 @@ static void kvm_arch_set_tsc_khz(CPUState *cs)
> int r;
>
> /*
> - * If no user-specified TSC frequency is present, we will try to
> - * set env->tsc_khz to the value used by KVM.
> + * For other cases of env->tsc_khz and env->user_tsc_khz:
> + *
> + * - We have eliminated all cases that satisfy
> + * env->tsc_khz && env->user_tsc_khz &&
> + * env->tsc_khz != env->user_tsc_khz
> + * in cpu_post_load().
> + *
> + * - If env->user_tsc_khz is not zero, then it must be equal to
> + * env->tsc_khz (if the latter is not zero) and has been set in
> + * kvm_arch_init_vcpu().
> + */
> + if (env->tsc_khz && !env->user_tsc_khz) {
> + r = kvm_check_extension(cs->kvm_state, KVM_CAP_TSC_CONTROL) ?
> + kvm_vcpu_ioctl(cs, KVM_SET_TSC_KHZ, env->tsc_khz) : -ENOTSUP;
Please don't duplicate the code from kvm_arch_init_vcpu(). We can
handle both cases in kvm_arch_put_registers(KVM_PUT_FULL_STATE),
can't we?
> + if (r < 0) {
> + error_report("warning: TSC frequency mismatch between VM and host, "
> + "and TSC scaling unavailable");
> + }
> + }
> +
> + /*
> + * If neither the user-specified TSC frequency nor the migrated
> + * 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) ?
> diff --git a/target-i386/machine.c b/target-i386/machine.c
> index a18e16e..eb062d2 100644
> --- a/target-i386/machine.c
> +++ b/target-i386/machine.c
> @@ -331,6 +331,13 @@ static int cpu_post_load(void *opaque, int version_id)
> CPUX86State *env = &cpu->env;
> int i;
>
> + if (env->tsc_khz && env->user_tsc_khz &&
> + env->tsc_khz != env->user_tsc_khz) {
> + fprintf(stderr, "Mismatch between user-specified TSC frequency and "
> + "migrated TSC frequency");
> + return -1;
> + }
> +
> /*
> * Real mode guest segments register DPL should be zero.
> * Older KVM version were setting it wrongly.
> @@ -775,6 +782,26 @@ static const VMStateDescription vmstate_xss = {
> }
> };
>
> +static bool tsc_khz_needed(void *opaque)
> +{
> + X86CPU *cpu = opaque;
> + CPUX86State *env = &cpu->env;
> + MachineClass *mc = MACHINE_GET_CLASS(qdev_get_machine());
> + PCMachineClass *pcmc = PC_MACHINE_CLASS(mc);
> + return env->tsc_khz && pcmc->save_tsc_khz;
> +}
> +
> +static const VMStateDescription vmstate_tsc_khz = {
> + .name = "cpu/tsc_khz",
> + .version_id = 1,
> + .minimum_version_id = 1,
> + .needed = tsc_khz_needed,
> + .fields = (VMStateField[]) {
> + VMSTATE_INT64(env.tsc_khz, X86CPU),
> + VMSTATE_END_OF_LIST()
> + }
> +};
> +
> VMStateDescription vmstate_x86_cpu = {
> .name = "cpu",
> .version_id = 12,
> @@ -895,6 +922,7 @@ VMStateDescription vmstate_x86_cpu = {
> &vmstate_msr_hyperv_runtime,
> &vmstate_avx512,
> &vmstate_xss,
> + &vmstate_tsc_khz,
> NULL
> }
> };
> --
> 2.4.8
>
--
Eduardo
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