Re: [Qemu-devel] [PATCH v13 2/5] i386: Introduce auto_topoext bit to manage topoext

[Moger, Babu]

Hi Eduardo,
Planning  to make couple of changes after testing and review.  Let me know if I 
missed something.
Will wait for your feedback before the next revision.

> -----Original Message-----
> From: address@hidden [mailto:address@hidden
> On Behalf Of Babu Moger
> Sent: Friday, June 8, 2018 5:56 PM
> To: address@hidden; address@hidden; address@hidden;
> address@hidden; address@hidden; address@hidden
> Cc: address@hidden; address@hidden; Moger, Babu
> <address@hidden>; address@hidden; address@hidden
> Subject: [PATCH v13 2/5] i386: Introduce auto_topoext bit to manage
> topoext
> 
> Introduce the auto_topoext bit to to control topoext feature.
> 
> Also add new field auto_topoext(in X86CPUDefinition). This will
> be used to enable topoext on newer CPU models where topoext can
> be supported.
> 
> Signed-off-by: Babu Moger <address@hidden>
> ---
>  include/hw/i386/pc.h |  4 ++++
>  target/i386/cpu.c    | 12 ++++++++++++
>  target/i386/cpu.h    |  5 +++++
>  3 files changed, 21 insertions(+)
> 
> diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
> index 04d1f8c..cc30ec3 100644
> --- a/include/hw/i386/pc.h
> +++ b/include/hw/i386/pc.h
> @@ -303,6 +303,10 @@ bool e820_get_entry(int, uint32_t, uint64_t *,
> uint64_t *);
>          .driver   = TYPE_X86_CPU,\
>          .property = "legacy-cache",\
>          .value    = "on",\
> +    },{\
> +        .driver   = TYPE_X86_CPU,\
> +        .property = "auto-topoext",\
> +        .value    = "off",\
>      },

We don't need this.  We are already setting this false in x86_cpu_properties.
But we need to set it "on" for EPYC on PC_COMPAT_3_0 whenever we define it. 
That will be a separate patch. Correct?

> 
>  #define PC_COMPAT_2_11 \
> diff --git a/target/i386/cpu.c b/target/i386/cpu.c
> index 86fb1a4..d3411ed 100644
> --- a/target/i386/cpu.c
> +++ b/target/i386/cpu.c
> @@ -1283,6 +1283,8 @@ struct X86CPUDefinition {
>      FeatureWordArray features;
>      const char *model_id;
>      CPUCaches *cache_info;
> +    /* Set it if topoext can be enabled in CPU models */
> +    int auto_topoext;
>  };
> 
>  static CPUCaches epyc_cache_info = {
> @@ -3517,6 +3519,9 @@ static void x86_cpu_load_def(X86CPU *cpu,
> X86CPUDefinition *def, Error **errp)
>      /* legacy-cache defaults to 'off' if CPU model provides cache info */
>      cpu->legacy_cache = !def->cache_info;
> 
> +    /* Set auto_topoext if both machine property and CPU model supports it
> */
> +    cpu->auto_topoext =  cpu->auto_topoext & def->auto_topoext;

This could be more appropriate like this.

 cpu->auto_topoext =  cpu->auto_topoext && def->auto_topoext;

> +
>      /* Special cases not set in the X86CPUDefinition structs: */
>      /* TODO: in-kernel irqchip for hvf */
>      if (kvm_enabled()) {
> @@ -5382,6 +5387,13 @@ static Property x86_cpu_properties[] = {
>      DEFINE_PROP_BOOL("legacy-cache", X86CPU, legacy_cache, true),
> 
>      /*
> +     * auto-topoext property will be used to enable topoext feature.
> +     * This will be disabled on all the older CPU models. Will be
> +     * enabled on newer CPU modeles which can support topology extention.
> +     */
> +     DEFINE_PROP_BOOL("auto-topoext", X86CPU, auto_topoext, false),
> +
> +    /*
>       * From "Requirements for Implementing the Microsoft
>       * Hypervisor Interface":
>       * https://docs.microsoft.com/en-us/virtualization/hyper-v-on-
> windows/reference/tlfs
> diff --git a/target/i386/cpu.h b/target/i386/cpu.h
> index 89c82be..8783d36 100644
> --- a/target/i386/cpu.h
> +++ b/target/i386/cpu.h
> @@ -1409,6 +1409,11 @@ struct X86CPU {
>       */
>      bool legacy_cache;
> 
> +    /* Compatibility bits to enable topoext feature on all newer machines
> +     * Disabled on older machines. Enabled on newer CPU models
> +     */
> +    bool auto_topoext;
> +
>      /* Compatibility bits for old machine types: */
>      bool enable_cpuid_0xb;
> 
> --
> 1.8.3.1