Re: [Qemu-devel] [PATCH v4 1/3] target-i386: KVM: add basic Intel LMCE support

[Eduardo Habkost]

On Thu, Jun 16, 2016 at 02:06:19PM +0800, Haozhong Zhang wrote:
> From: Ashok Raj <address@hidden>
> 
> This patch adds the support to inject SRAR and SRAO as LMCE, i.e. they
> are injected to only one VCPU rather than broadcast to all VCPUs. As KVM
> reports LMCE support on Intel platforms, this features is only available
> on Intel platforms.
> 
> LMCE is disabled by default and can be enabled/disabled by cpu option
> 'lmce=on/off'.
> 
> Signed-off-by: Ashok Raj <address@hidden>
> [Haozhong: Enable LMCE only on Intel platforms
>            Disable LMCE by default and add a cpu option 'lmce'
>          Disable LMCE if missing KVM support
>          Remove MCG_LMCE_P from MCE_CAP_DEF
>          Minor code style changes]

You are mixing tabs and spaces above.

> Signed-off-by: Haozhong Zhang <address@hidden>
> ---
>  target-i386/cpu.c | 23 +++++++++++++++++++++++
>  target-i386/cpu.h | 12 ++++++++++++
>  target-i386/kvm.c | 35 +++++++++++++++++++++++++++++++----
>  3 files changed, 66 insertions(+), 4 deletions(-)
> 
> diff --git a/target-i386/cpu.c b/target-i386/cpu.c
> index 895a386..bd35db2 100644
> --- a/target-i386/cpu.c
> +++ b/target-i386/cpu.c
> @@ -2777,15 +2777,37 @@ static void x86_cpu_machine_reset_cb(void *opaque)
>  }
>  #endif
>  
> +static bool lmce_supported(void)
> +{
> +    uint64_t mce_cap;
> +
> +    if (!kvm_enabled() ||
> +        kvm_ioctl(kvm_state, KVM_X86_GET_MCE_CAP_SUPPORTED, &mce_cap) < 0) {
> +        return false;
> +    }
> +
> +    return !!(mce_cap & MCG_LMCE_P);
> +}
> +
>  static void mce_init(X86CPU *cpu)
>  {
>      CPUX86State *cenv = &cpu->env;
>      unsigned int bank;
> +    Error *local_err = NULL;
>  
>      if (((cenv->cpuid_version >> 8) & 0xf) >= 6
>          && (cenv->features[FEAT_1_EDX] & (CPUID_MCE | CPUID_MCA)) ==
>              (CPUID_MCE | CPUID_MCA)) {
>          cenv->mcg_cap = MCE_CAP_DEF | MCE_BANKS_DEF;
> +
> +        if (cpu->enable_lmce) {
> +            if (!lmce_supported()) {
> +                error_setg(&local_err, "KVM unavailable or LMCE not 
> supported");
> +                error_propagate(&error_abort, local_err);
> +            }
> +            cenv->mcg_cap |= MCG_LMCE_P;
> +        }
> +

This duplicates the existing check in kvm_arch_init_vcpu(). The
difference is that the existing code is KVM-specific and doesn't
stop initialization when capabilities are missing. We can unify
them into a single mcg_cap-checking function as a follow-up.

-- 
Eduardo