Re: [Xen-devel] [PATCH v3 07/32] xen/x86: fix arch_set_info_guest for HVM guests

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 03/07/15 12:34, Roger Pau Monne wrote:
> Add checks for ignored vcpu fields in HVM mode. HVM vCPUs (BSP and APs) are
> always started in 32bit protected mode with paging disabled.
>
> Signed-off-by: Roger Pau Monnà <roger.pau@xxxxxxxxxx>
> Cc: Jan Beulich <jbeulich@xxxxxxxx>
> Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> ---
>  xen/arch/x86/domain.c | 14 +++++++++++---
>  1 file changed, 11 insertions(+), 3 deletions(-)
>
> diff --git a/xen/arch/x86/domain.c b/xen/arch/x86/domain.c
> index a8fe046..a112953 100644
> --- a/xen/arch/x86/domain.c
> +++ b/xen/arch/x86/domain.c
> @@ -795,6 +795,15 @@ int arch_set_info_guest(
>                c.nat->fs_base || c.nat->gs_base_user)) )
>              return -EINVAL;
>      }
> +    else if ( is_hvm_domain(d) )
> +    {
> +        if ( c(ctrlreg[0]) || c(ctrlreg[1]) || c(ctrlreg[2]) ||
> +             c(ctrlreg[3]) || c(ctrlreg[4]) || c(ctrlreg[5]) ||

I am not sure that the cr0 and cr4 checks are sensible.  While the new
ABI doesn't need them, there is nothing inherently wrong with setting
them via this interface.

> +             c(ctrlreg[6]) || c(ctrlreg[7]) || c(ldt_base) ||
> +             c(ldt_ents) || c(kernel_ss) || c(kernel_sp) ||
> +             c(gdt_ents) )
> +            return -EINVAL;
> +    }
>  
>      v->fpu_initialised = !!(flags & VGCF_I387_VALID);
>  
> @@ -1064,15 +1073,14 @@ int arch_set_info_guest(
>      if ( v->vcpu_id == 0 )
>          update_domain_wallclock_time(d);
>  
> -    /* Don't redo final setup */
> -    v->is_initialised = 1;
> -

Is this a bugfix, or spurious movement?

~Andrew

>      if ( paging_mode_enabled(d) )
>          paging_update_paging_modes(v);
>  
>      update_cr3(v);
>  
>   out:
> +    /* Don't redo final setup */
> +    v->is_initialised = 1;
>      if ( flags & VGCF_online )
>          clear_bit(_VPF_down, &v->pause_flags);
>      else


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