Re: [Xen-devel] [PATCH] microcode: Check whether the microcode is correct.

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 19.07.13 at 05:59, Konrad Rzeszutek Wilk <konrad@xxxxxxxxxx> wrote:
> --- a/xen/arch/x86/microcode.c
> +++ b/xen/arch/x86/microcode.c
> @@ -433,24 +433,40 @@ static int __init microcode_presmp_init(void)
>      {
>          if ( ucode_mod.mod_end || ucode_blob.size )
>          {
> -            void *data;
> -            size_t len;
> -
> -            if ( ucode_blob.size )
> -            {
> -                len = ucode_blob.size;
> -                data = ucode_blob.data;
> -            }
> -            else
> -            {
> -                len = ucode_mod.mod_end;
> -                data = ucode_mod_map(&ucode_mod);
> -            }
> -            if ( data )
> -                microcode_update_cpu(data, len);
> -
> -            if ( !ucode_blob.size )
> -                ucode_mod_map(NULL);
> +            int rc;
> +            do {
> +                void *data = NULL;
> +                size_t len;
> +
> +                rc = 0;
> +                if ( ucode_blob.size )
> +                {
> +                    len = ucode_blob.size;
> +                    data = ucode_blob.data;
> +                }
> +                else if ( ucode_mod.mod_end )
> +                {
> +                    len = ucode_mod.mod_end;
> +                    data = ucode_mod_map(&ucode_mod);
> +                }
> +                if ( data )
> +                    rc = microcode_update_cpu(data, len);

else rc = -ENOMEM (yielding the initialization above pointless).

> +
> +                if ( !ucode_blob.size && ucode_mod.mod_end )
> +                    ucode_mod_map(NULL);
> +
> +                if ( rc == -EINVAL )

if ( rc )

> +                {
> +                    if ( ucode_blob.size ) /* That was tried first */
> +                    {
> +                        ucode_blob.size = 0;
> +                        xfree(ucode_blob.data);
> +                        continue;
> +                    }
> +                    if ( ucode_mod.mod_end )
> +                        ucode_mod.mod_end = 0;
> +                }
> +            } while ( rc );
>          }
>  
>          register_cpu_notifier(&microcode_percpu_nfb);

This may need re-doing anyway I we can agree that allowing both
location specifications at the same time is bogus and should hence
be dropped.

Jan



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