Re: [Qemu-devel] [PATCH] i386: Add support to get/set/migrate MSR (33H)

[Paolo Bonzini <pbonzini@redhat.com>]

On 04/07/2018 15:21, Jingqi Liu wrote:
> The MSR (33H) controls support for #AC exception
> for split locked accesses. When bit 29 of the MSR (33H)
> is set, the processor causes an #AC exception to
> be issued instead of suppressing LOCK on bus
> (during split lock access).
> 
> Signed-off-by: Jingqi Liu <jingqi.liu@intel.com>
> ---
>  target/i386/cpu.h     |  2 ++
>  target/i386/kvm.c     | 13 +++++++++++++
>  target/i386/machine.c | 20 ++++++++++++++++++++
>  3 files changed, 35 insertions(+)
> 
> diff --git a/target/i386/cpu.h b/target/i386/cpu.h
> index 8eaefee..9728552 100644
> --- a/target/i386/cpu.h
> +++ b/target/i386/cpu.h
> @@ -348,6 +348,7 @@ typedef enum X86Seg {
>  #define MSR_IA32_APICBASE_ENABLE        (1<<11)
>  #define MSR_IA32_APICBASE_EXTD          (1 << 10)
>  #define MSR_IA32_APICBASE_BASE          (0xfffffU<<12)
> +#define MSR_SPLIT_LOCK_CTRL             0x00000033
>  #define MSR_IA32_FEATURE_CONTROL        0x0000003a
>  #define MSR_TSC_ADJUST                  0x0000003b
>  #define MSR_IA32_SPEC_CTRL              0x48
> @@ -1209,6 +1210,7 @@ typedef struct CPUX86State {
>      uint32_t pkru;
>  
>      uint64_t spec_ctrl;
> +    uint64_t split_lock_ctrl;

Please call everything MSR_TEST_CTL or test_ctl.  Yes, it's a horrible
name, but if that's what the manual calls it, we should do the same.

Thanks,

Paolo

>      uint64_t virt_ssbd;
>  
>      /* End of state preserved by INIT (dummy marker).  */
> diff --git a/target/i386/kvm.c b/target/i386/kvm.c
> index 032f0ad..043ca9b 100644
> --- a/target/i386/kvm.c
> +++ b/target/i386/kvm.c
> @@ -92,6 +92,7 @@ static bool has_msr_hv_frequencies;
>  static bool has_msr_hv_reenlightenment;
>  static bool has_msr_xss;
>  static bool has_msr_spec_ctrl;
> +static bool has_msr_split_lock_ctrl;
>  static bool has_msr_virt_ssbd;
>  static bool has_msr_smi_count;
>  
> @@ -1272,6 +1273,9 @@ static int kvm_get_supported_msrs(KVMState *s)
>                  case MSR_IA32_SPEC_CTRL:
>                      has_msr_spec_ctrl = true;
>                      break;
> +                case MSR_SPLIT_LOCK_CTRL:
> +                    has_msr_split_lock_ctrl = true;
> +                    break;
>                  case MSR_VIRT_SSBD:
>                      has_msr_virt_ssbd = true;
>                      break;
> @@ -1786,6 +1790,9 @@ static int kvm_put_msrs(X86CPU *cpu, int level)
>      if (has_msr_spec_ctrl) {
>          kvm_msr_entry_add(cpu, MSR_IA32_SPEC_CTRL, env->spec_ctrl);
>      }
> +    if (has_msr_split_lock_ctrl) {
> +        kvm_msr_entry_add(cpu, MSR_SPLIT_LOCK_CTRL, env->split_lock_ctrl);
> +    }
>      if (has_msr_virt_ssbd) {
>          kvm_msr_entry_add(cpu, MSR_VIRT_SSBD, env->virt_ssbd);
>      }
> @@ -2169,6 +2176,9 @@ static int kvm_get_msrs(X86CPU *cpu)
>      if (has_msr_spec_ctrl) {
>          kvm_msr_entry_add(cpu, MSR_IA32_SPEC_CTRL, 0);
>      }
> +    if (has_msr_split_lock_ctrl) {
> +        kvm_msr_entry_add(cpu, MSR_SPLIT_LOCK_CTRL, 0);
> +    }
>      if (has_msr_virt_ssbd) {
>          kvm_msr_entry_add(cpu, MSR_VIRT_SSBD, 0);
>      }
> @@ -2551,6 +2561,9 @@ static int kvm_get_msrs(X86CPU *cpu)
>          case MSR_IA32_SPEC_CTRL:
>              env->spec_ctrl = msrs[i].data;
>              break;
> +        case MSR_SPLIT_LOCK_CTRL:
> +            env->split_lock_ctrl = msrs[i].data;
> +            break;
>          case MSR_VIRT_SSBD:
>              env->virt_ssbd = msrs[i].data;
>              break;
> diff --git a/target/i386/machine.c b/target/i386/machine.c
> index 4d98d36..c82dc0d 100644
> --- a/target/i386/machine.c
> +++ b/target/i386/machine.c
> @@ -935,6 +935,25 @@ static const VMStateDescription vmstate_msr_virt_ssbd = {
>      }
>  };
>  
> +static bool split_lock_ctrl_needed(void *opaque)
> +{
> +    X86CPU *cpu = opaque;
> +    CPUX86State *env = &cpu->env;
> +
> +    return env->split_lock_ctrl != 0;
> +}
> +
> +static const VMStateDescription vmstate_split_lock_ctrl = {
> +    .name = "cpu/split_lock_ctrl",
> +    .version_id = 1,
> +    .minimum_version_id = 1,
> +    .needed = split_lock_ctrl_needed,
> +    .fields = (VMStateField[]){
> +        VMSTATE_UINT64(env.split_lock_ctrl, X86CPU),
> +        VMSTATE_END_OF_LIST()
> +    }
> +};
> +
>  VMStateDescription vmstate_x86_cpu = {
>      .name = "cpu",
>      .version_id = 12,
> @@ -1059,6 +1078,7 @@ VMStateDescription vmstate_x86_cpu = {
>          &vmstate_mcg_ext_ctl,
>          &vmstate_msr_intel_pt,
>          &vmstate_msr_virt_ssbd,
> +        &vmstate_split_lock_ctrl,
>          NULL
>      }
>  };
>