Re: [Xen-devel] [PATCH v2] x86: MSR_IA32_BNDCFGS save/restore

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 13/12/2013 14:02, Jan Beulich wrote:
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
>
> --- a/xen/arch/x86/hvm/vmx/vmx.c
> +++ b/xen/arch/x86/hvm/vmx/vmx.c
> @@ -580,6 +580,55 @@ static int vmx_load_vmcs_ctxt(struct vcp
>      return 0;
>  }
>  
> +static unsigned int __init vmx_init_msr(void)
> +{
> +    return !!cpu_has_mpx;
> +}
> +
> +static void vmx_save_msr(struct vcpu *v, struct hvm_msr *ctxt)
> +{
> +    vmx_vmcs_enter(v);
> +
> +    if ( cpu_has_mpx )
> +    {
> +        __vmread(GUEST_BNDCFGS, &ctxt->msr[ctxt->count].val);
> +        if ( ctxt->msr[ctxt->count].val )
> +            ctxt->msr[ctxt->count++].index = MSR_IA32_BNDCFGS;
> +    }
> +
> +    vmx_vmcs_exit(v);
> +}
> +
> +static int vmx_load_msr(struct vcpu *v, struct hvm_msr *ctxt)
> +{
> +    unsigned int i;
> +    int err = 0;
> +
> +    vmx_vmcs_enter(v);
> +
> +    for ( i = 0; i < ctxt->count; ++i )
> +    {
> +        switch ( ctxt->msr[i].index )
> +        {
> +        case MSR_IA32_BNDCFGS:
> +            if ( cpu_has_mpx )
> +                __vmwrite(GUEST_BNDCFGS, ctxt->msr[i].val);
> +            else
> +                err = -ENXIO;
> +            break;
> +        default:
> +            continue;

This will skip setting _rsvd for an MSR we don't recognise.  Doesn't
this interfere with the error checking in the caller?

~Andrew

> +        }
> +        if ( err )
> +            break;
> +        ctxt->msr[i]._rsvd = 1;
> +    }
> +
> +    vmx_vmcs_exit(v);
> +
> +    return err;
> +}
> +
>  static void vmx_fpu_enter(struct vcpu *v)
>  {
>      vcpu_restore_fpu_lazy(v);
> @@ -1602,6 +1651,9 @@ static struct hvm_function_table __initd
>      .vcpu_destroy         = vmx_vcpu_destroy,
>      .save_cpu_ctxt        = vmx_save_vmcs_ctxt,
>      .load_cpu_ctxt        = vmx_load_vmcs_ctxt,
> +    .init_msr             = vmx_init_msr,
> +    .save_msr             = vmx_save_msr,
> +    .load_msr             = vmx_load_msr,
>      .get_interrupt_shadow = vmx_get_interrupt_shadow,
>      .set_interrupt_shadow = vmx_set_interrupt_shadow,
>      .guest_x86_mode       = vmx_guest_x86_mode,
> --- a/xen/include/asm-x86/hvm/vmx/vmcs.h
> +++ b/xen/include/asm-x86/hvm/vmx/vmcs.h
> @@ -367,6 +367,8 @@ enum vmcs_field {
>      GUEST_PDPTR2_HIGH               = 0x0000280f,
>      GUEST_PDPTR3                    = 0x00002810,
>      GUEST_PDPTR3_HIGH               = 0x00002811,
> +    GUEST_BNDCFGS                   = 0x00002812,
> +    GUEST_BNDCFGS_HIGH              = 0x00002813,
>      HOST_PAT                        = 0x00002c00,
>      HOST_PAT_HIGH                   = 0x00002c01,
>      HOST_EFER                       = 0x00002c02,
>
>
>


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