Re: [Qemu-devel] [PATCH v4 3/3] i386: publish advised value of MSR_IA32_FEATURE_CONTROL via fw_cfg

[Paolo Bonzini]

On 16/06/2016 08:06, Haozhong Zhang wrote:
> It's a prerequisite that certain bits of MSR_IA32_FEATURE_CONTROL should
> be set before some features (e.g. VMX and LMCE) can be used, which is
> usually done by the firmware. This patch adds a fw_cfg file
> "etc/msr_feature_control" which contains the advised value of
> MSR_IA32_FEATURE_CONTROL and can be used by guest firmware (e.g. SeaBIOS).
> 
> Suggested-by: Paolo Bonzini <address@hidden>
> Signed-off-by: Haozhong Zhang <address@hidden>
> ---
>  hw/i386/pc.c      | 28 ++++++++++++++++++++++++++++
>  target-i386/cpu.h |  4 ++++
>  2 files changed, 32 insertions(+)
> 
> diff --git a/hw/i386/pc.c b/hw/i386/pc.c
> index 7198ed5..d8178a5 100644
> --- a/hw/i386/pc.c
> +++ b/hw/i386/pc.c
> @@ -1147,6 +1147,33 @@ void pc_cpus_init(PCMachineState *pcms)
>      smbios_set_cpuid(cpu->env.cpuid_version, cpu->env.features[FEAT_1_EDX]);
>  }
>  
> +static void pc_build_feature_control_file(PCMachineState *pcms)
> +{
> +    X86CPU *cpu = X86_CPU(pcms->possible_cpus->cpus[0].cpu);
> +    CPUX86State *env = &cpu->env;
> +    uint32_t unused, ecx, edx, feature_control_bits = 0;
> +    uint32_t *val;
> +
> +    cpu_x86_cpuid(env, 1, 0, &unused, &unused, &ecx, &edx);
> +    if (ecx & CPUID_EXT_VMX) {
> +        feature_control_bits |= FEATURE_CONTROL_VMXON_ENABLED_OUTSIDE_SMX;
> +    }
> +
> +    if ((edx & (CPUID_EXT2_MCE | CPUID_EXT2_MCA)) ==
> +        (CPUID_EXT2_MCE | CPUID_EXT2_MCA) &&
> +        (env->mcg_cap & MCG_LMCE_P)) {
> +        feature_control_bits |= FEATURE_CONTROL_LMCE;
> +    }
> +
> +    if (!feature_control_bits) {
> +        return;
> +    }
> +
> +    val = g_malloc(sizeof(*val));
> +    *val = feature_control_bits | FEATURE_CONTROL_LOCKED;
> +    fw_cfg_add_file(pcms->fw_cfg, "etc/msr_feature_control", val, 
> sizeof(*val));
> +}
> +
>  static
>  void pc_machine_done(Notifier *notifier, void *data)
>  {
> @@ -1174,6 +1201,7 @@ void pc_machine_done(Notifier *notifier, void *data)
>      acpi_setup();
>      if (pcms->fw_cfg) {
>          pc_build_smbios(pcms->fw_cfg);
> +        pc_build_feature_control_file(pcms);
>      }
>  }
>  
> diff --git a/target-i386/cpu.h b/target-i386/cpu.h
> index f0cb04f..5e07c7a 100644
> --- a/target-i386/cpu.h
> +++ b/target-i386/cpu.h
> @@ -332,6 +332,10 @@
>  #define MSR_TSC_ADJUST                  0x0000003b
>  #define MSR_IA32_TSCDEADLINE            0x6e0
>  
> +#define FEATURE_CONTROL_LOCKED                    (1<<0)
> +#define FEATURE_CONTROL_VMXON_ENABLED_OUTSIDE_SMX (1<<2)
> +#define FEATURE_CONTROL_LMCE                      (1<<20)
> +
>  #define MSR_P6_PERFCTR0                 0xc1
>  
>  #define MSR_IA32_SMBASE                 0x9e
> 

Reviewed-by: Paolo Bonzini <address@hidden>

Have you prepared a patch for SeaBIOS already?

Thanks,

Paolo