Re: Add savevm/loadvm support for MCE

[Jan Kiszka <jan.kiszka@siemens.com>]

Huang Ying wrote:
> MCE registers are saved/load into/from CPUState in
> kvm_arch_save/load_regs. Because all MCE registers except for
> MCG_STATUS should be preserved, MCE registers are saved before
> kvm_arch_load_regs in kvm_arch_cpu_reset. To simulate the MCG_STATUS
> clearing upon reset, env->mcg_status is set to 0 after saving.

That should be solved differently on top of [1]: Write back
MSR_MCG_STATUS on KVM_PUT_RESET_STATE, write all MCE MSRs on
KVM_PUT_FULL_STATE. Then you can also unfold kvm_load/save_mce_regs to
avoid duplicating its infrastructure (becomes even more obvious when
looking at kvm_get/put/_msrs in upstream).

> 
> Signed-off-by: Huang Ying <ying.huang@intel.com>
> 
> ---
>  qemu-kvm-x86.c |   54 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 54 insertions(+)
> 
> --- a/qemu-kvm-x86.c
> +++ b/qemu-kvm-x86.c
> @@ -803,6 +803,27 @@ static void get_seg(SegmentCache *lhs, c
>  	| (rhs->avl * DESC_AVL_MASK);
>  }
>  
> +static void kvm_load_mce_regs(CPUState *env)
> +{
> +#ifdef KVM_CAP_MCE
> +    struct kvm_msr_entry msrs[100];
> +    int rc, n, i;
> +
> +    if (!env->mcg_cap)
> +	    return;
> +
> +    n = 0;
> +    set_msr_entry(&msrs[n++], MSR_MCG_STATUS, env->mcg_status);
> +    set_msr_entry(&msrs[n++], MSR_MCG_CTL, env->mcg_ctl);
> +    for (i = 0; i < (env->mcg_cap & 0xff) * 4; i++)
> +        set_msr_entry(&msrs[n++], MSR_MC0_CTL + i, env->mce_banks[i]);
> +
> +    rc = kvm_set_msrs(env, msrs, n);
> +    if (rc == -1)
> +        perror("kvm_set_msrs FAILED");
> +#endif
> +}
> +
>  void kvm_arch_load_regs(CPUState *env)
>  {
>      struct kvm_regs regs;
> @@ -922,6 +943,8 @@ void kvm_arch_load_regs(CPUState *env)
>      if (rc == -1)
>          perror("kvm_set_msrs FAILED");
>  
> +    kvm_load_mce_regs(env);
> +
>      /*
>       * Kernels before 2.6.33 (which correlates with !kvm_has_vcpu_events())
>       * overwrote flags.TF injected via SET_GUEST_DEBUG while updating GP regs.
> @@ -991,6 +1014,33 @@ void kvm_arch_load_mpstate(CPUState *env
>  #endif
>  }
>  
> +static void kvm_save_mce_regs(CPUState *env)
> +{
> +#ifdef KVM_CAP_MCE
> +    struct kvm_msr_entry msrs[100];
> +    int rc, n, i;
> +
> +    if (!env->mcg_cap)
> +	    return;
> +
> +    msrs[0].index = MSR_MCG_STATUS;
> +    msrs[1].index = MSR_MCG_CTL;
> +    n = (env->mcg_cap & 0xff) * 4;
> +    for (i = 0; i < n; i++)
> +        msrs[2 + i].index = MSR_MC0_CTL + i;
> +
> +    rc = kvm_get_msrs(env, msrs, n + 2);
> +    if (rc == -1)
> +        perror("kvm_set_msrs FAILED");
> +    else {
> +        env->mcg_status = msrs[0].data;
> +        env->mcg_ctl = msrs[1].data;
> +        for (i = 0; i < n; i++)
> +            env->mce_banks[i] = msrs[2 + i].data;
> +    }
> +#endif
> +}
> +
>  void kvm_arch_save_regs(CPUState *env)
>  {
>      struct kvm_regs regs;
> @@ -1148,6 +1198,7 @@ void kvm_arch_save_regs(CPUState *env)
>          }
>      }
>      kvm_arch_save_mpstate(env);
> +    kvm_save_mce_regs(env);
>  }
>  
>  static void do_cpuid_ent(struct kvm_cpuid_entry2 *e, uint32_t function,
> @@ -1385,6 +1436,9 @@ void kvm_arch_push_nmi(void *opaque)
>  void kvm_arch_cpu_reset(CPUState *env)
>  {
>      kvm_arch_reset_vcpu(env);
> +    /* MCE registers except MCG_STATUS should be unchanged across reset */
> +    kvm_save_mce_regs(env);
> +    env->mcg_status = 0;
>      kvm_arch_load_regs(env);
>      kvm_put_vcpu_events(env);
>      if (!cpu_is_bsp(env)) {
> 
> 

Jan

[1] http://thread.gmane.org/gmane.comp.emulators.kvm.devel/47411

-- 
Siemens AG, Corporate Technology, CT T DE IT 1
Corporate Competence Center Embedded Linux