Re: [Qemu-devel] [PATCH v3 2/3] target-i386: calculate vcpu's TSC rate to be migrated

[James Hogan]

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 <address@hidden>
> ---
>  include/sysemu/kvm.h |  2 ++
>  kvm-all.c            |  1 +
>  target-arm/kvm.c     |  5 +++++
>  target-i386/kvm.c    | 33 +++++++++++++++++++++++++++++++++
>  target-mips/kvm.c    |  5 +++++
>  target-ppc/kvm.c     |  5 +++++
>  target-s390x/kvm.c   |  5 +++++
>  7 files changed, 56 insertions(+)
> 
> diff --git a/include/sysemu/kvm.h b/include/sysemu/kvm.h
> index 461ef65..0ec8b98 100644
> --- a/include/sysemu/kvm.h
> +++ b/include/sysemu/kvm.h
> @@ -328,6 +328,8 @@ int kvm_arch_fixup_msi_route(struct kvm_irq_routing_entry 
> *route,
>  
>  int kvm_arch_msi_data_to_gsi(uint32_t data);
>  
> +int kvm_arch_setup_tsc_khz(CPUState *cpu);
> +
>  int kvm_set_irq(KVMState *s, int irq, int level);
>  int kvm_irqchip_send_msi(KVMState *s, MSIMessage msg);
>  
> diff --git a/kvm-all.c b/kvm-all.c
> index c442838..1ecaf04 100644
> --- a/kvm-all.c
> +++ b/kvm-all.c
> @@ -1757,6 +1757,7 @@ static void do_kvm_cpu_synchronize_post_init(void *arg)
>  {
>      CPUState *cpu = arg;
>  
> +    kvm_arch_setup_tsc_khz(cpu);

Sorry if this is a stupid question, but why aren't you doing this from
the i386 kvm_arch_put_registers when level == KVM_PUT_FULL_STATE, rather
than introducing x86 specifics to the generic KVM api?

Cheers
James

>      kvm_arch_put_registers(cpu, KVM_PUT_FULL_STATE);
>      cpu->kvm_vcpu_dirty = false;
>  }
> diff --git a/target-arm/kvm.c b/target-arm/kvm.c
> index 79ef4c6..a724f6d 100644
> --- a/target-arm/kvm.c
> +++ b/target-arm/kvm.c
> @@ -614,3 +614,8 @@ int kvm_arch_msi_data_to_gsi(uint32_t data)
>  {
>      return (data - 32) & 0xffff;
>  }
> +
> +int kvm_arch_setup_tsc_khz(CPUState *cs)
> +{
> +    return 0;
> +}
> 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;
> +        }
> +        env->tsc_khz_saved = r;
> +    }
> +
> +    return 0;
> +}
> diff --git a/target-mips/kvm.c b/target-mips/kvm.c
> index 12d7db3..fb26d7e 100644
> --- a/target-mips/kvm.c
> +++ b/target-mips/kvm.c
> @@ -687,3 +687,8 @@ int kvm_arch_msi_data_to_gsi(uint32_t data)
>  {
>      abort();
>  }
> +
> +int kvm_arch_setup_tsc_khz(CPUState *cs)
> +{
> +    return 0;
> +}
> diff --git a/target-ppc/kvm.c b/target-ppc/kvm.c
> index ac70f08..c429f0c 100644
> --- a/target-ppc/kvm.c
> +++ b/target-ppc/kvm.c
> @@ -2510,3 +2510,8 @@ int kvmppc_enable_hwrng(void)
>  
>      return kvmppc_enable_hcall(kvm_state, H_RANDOM);
>  }
> +
> +int kvm_arch_setup_tsc_khz(CPUState *cs)
> +{
> +    return 0;
> +}
> diff --git a/target-s390x/kvm.c b/target-s390x/kvm.c
> index c3be180..db5d436 100644
> --- a/target-s390x/kvm.c
> +++ b/target-s390x/kvm.c
> @@ -2248,3 +2248,8 @@ int kvm_arch_msi_data_to_gsi(uint32_t data)
>  {
>      abort();
>  }
> +
> +int kvm_arch_setup_tsc_khz(CPUState *cs)
> +{
> +    return 0;
> +}
> -- 
> 2.4.8
>

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