Re: [Xen-devel] [PATCH] x86/AMD: Add support for AMD's OSVW feature in guests

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 30.01.12 at 18:05, Boris Ostrovsky <boris.ostrovsky@xxxxxxx> wrote:
> --- a/xen/arch/x86/microcode.c        Thu Jan 26 17:43:31 2012 +0000
> +++ b/xen/arch/x86/microcode.c        Mon Jan 30 18:00:50 2012 +0100
> @@ -218,6 +218,16 @@ int microcode_update(XEN_GUEST_HANDLE(co
>      info->error = 0;
>      info->cpu = cpumask_first(&cpu_online_map);
>  
> +    if ( microcode_ops->start_update )
> +    {
> +     ret = microcode_ops->start_update();
> +     if ( ret != 0 )
> +        {
> +         xfree(info);
> +         return ret;
> +     }

Indentation (no tabs).

> +    }
> +
>      return continue_hypercall_on_cpu(info->cpu, do_microcode_update, info);
>  }
>  
> --- a/xen/arch/x86/microcode_amd.c    Thu Jan 26 17:43:31 2012 +0000
> +++ b/xen/arch/x86/microcode_amd.c    Mon Jan 30 18:00:50 2012 +0100
> @@ -337,13 +341,18 @@ static int cpu_request_microcode(int cpu
>      /* On success keep the microcode patch for
>       * re-apply on resume.
>       */
> -    if (error == 1)
> +    if ( error == 1 )
>      {
>          xfree(mc_old);
> -        return 0;
> +        error = 0;
> +    } else 

    }
    else

> +    {
> +        xfree(mc_amd);
> +        uci->mc.mc_amd = mc_old;
>      }
> -    xfree(mc_amd);
> -    uci->mc.mc_amd = mc_old;
> +
> +  out:
> +    svm_host_osvw_init();
>  
>      return error;
>  }
> --- a/xen/arch/x86/platform_hypercall.c       Thu Jan 26 17:43:31 2012 +0000
> +++ b/xen/arch/x86/platform_hypercall.c       Mon Jan 30 18:00:50 2012 +0100
> @@ -166,7 +166,17 @@ ret_t do_platform_op(XEN_GUEST_HANDLE(xe
>              break;
>  
>          guest_from_compat_handle(data, op->u.microcode.data);
> +
> +        while ( !domctl_lock_acquire() )

It's not clear to me what you're trying to protect against here. I don't
think this prevents guests from making progress (and hence possibly
seeing the intermediate [and wrong] OSVW state between
svm_host_osvw_reset() and svm_host_osvw_init()).

Jan

> +            if ( hypercall_preempt_check() )
> +            {
> +                ret = hypercall_create_continuation(
> +                    __HYPERVISOR_platform_op, "h", u_xenpf_op);
> +                goto out;
> +            }
> +
>          ret = microcode_update(data, op->u.microcode.length);
> +        domctl_lock_release();
>      }
>      break;
>  



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