* Vitaly Kuznetsov (vkuzn...@redhat.com) wrote:
> KVM doesn't fully support Hyper-V reenlightenment notifications on
> migration. In particular, it doesn't support emulating TSC frequency
> of the source host by trapping all TSC accesses so unless TSC scaling
> is supported on the destination host and KVM_SET_TSC_KHZ succeeds, it
> is unsafe to proceed with migration.
>
> Normally, we only require KVM_SET_TSC_KHZ to succeed when 'user_tsc_khz'
> was set and just 'try' KVM_SET_TSC_KHZ without otherwise.
>
> Introduce a new vmstate section (which is added when the guest has
> reenlightenment feature enabled) and add env.tsc_khz to it. We already
> have env.tsc_khz packed in 'cpu/tsc_khz' but we don't want to be dependent
> on the section order.
>
> Signed-off-by: Vitaly Kuznetsov <vkuzn...@redhat.com>
> ---
> target/i386/kvm/hyperv.h | 1 +
> target/i386/kvm/kvm.c | 11 +++++++++++
> target/i386/machine.c | 37 +++++++++++++++++++++++++++++++++++++
> 3 files changed, 49 insertions(+)
>
> diff --git a/target/i386/kvm/hyperv.h b/target/i386/kvm/hyperv.h
> index 67543296c3a4..c65e5c85c4d3 100644
> --- a/target/i386/kvm/hyperv.h
> +++ b/target/i386/kvm/hyperv.h
> @@ -20,6 +20,7 @@
>
> #ifdef CONFIG_KVM
> int kvm_hv_handle_exit(X86CPU *cpu, struct kvm_hyperv_exit *exit);
> +int kvm_hv_tsc_frequency_loaded(X86CPU *cpu);
> #endif
>
> int hyperv_x86_synic_add(X86CPU *cpu);
> diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c
> index 7fe9f527103c..f6c4093778e9 100644
> --- a/target/i386/kvm/kvm.c
> +++ b/target/i386/kvm/kvm.c
> @@ -1460,6 +1460,17 @@ static int hyperv_init_vcpu(X86CPU *cpu)
> return 0;
> }
>
> +int kvm_hv_tsc_frequency_loaded(X86CPU *cpu)
> +{
> + CPUState *cs = CPU(cpu);
> +
> + /*
> + * KVM doens't fully support re-enlightenment notifications so we need to
^^
tpyo
Dave
> + * make sure TSC frequency doesn't change upon migration.
> + */
> + return kvm_arch_set_tsc_khz(cs);
> +}
> +
> static Error *invtsc_mig_blocker;
>
> #define KVM_MAX_CPUID_ENTRIES 100
> diff --git a/target/i386/machine.c b/target/i386/machine.c
> index 715620c58809..369a8f1e7a7a 100644
> --- a/target/i386/machine.c
> +++ b/target/i386/machine.c
> @@ -896,6 +896,42 @@ static const VMStateDescription
> vmstate_msr_hyperv_reenlightenment = {
> VMSTATE_END_OF_LIST()
> }
> };
> +
> +static bool hyperv_tsc_frequency_needed(void *opaque)
> +{
> + X86CPU *cpu = opaque;
> + CPUX86State *env = &cpu->env;
> +
> + return env->tsc_khz != 0 && (env->msr_hv_reenlightenment_control ||
> + env->msr_hv_tsc_emulation_control);
> +}
> +
> +static int hyperv_tsc_frequency_post_load(void *opaque, int version_id)
> +{
> + X86CPU *cpu = opaque;
> + int r;
> +
> + r = kvm_hv_tsc_frequency_loaded(cpu);
> + if (r) {
> + error_report("Failed to set the desired TSC frequency and "
> + "reenlightenment was exposed");
> + return -EINVAL;
> + }
> +
> + return 0;
> +}
> +
> +static const VMStateDescription vmstate_msr_hyperv_tsc_frequency = {
> + .name = "cpu/msr_hyperv_tsc_frequency",
> + .version_id = 1,
> + .minimum_version_id = 1,
> + .needed = hyperv_tsc_frequency_needed,
> + .post_load = hyperv_tsc_frequency_post_load,
> + .fields = (VMStateField[]) {
> + VMSTATE_INT64(env.tsc_khz, X86CPU),
> + VMSTATE_END_OF_LIST()
> + }
> +};
> #endif
>
> static bool avx512_needed(void *opaque)
> @@ -1495,6 +1531,7 @@ VMStateDescription vmstate_x86_cpu = {
> &vmstate_msr_hyperv_synic,
> &vmstate_msr_hyperv_stimer,
> &vmstate_msr_hyperv_reenlightenment,
> + &vmstate_msr_hyperv_tsc_frequency,
> #endif
> &vmstate_avx512,
> &vmstate_xss,
> --
> 2.30.2
>
--
Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK
