[Xen-devel] RE: [PATCH] to put dmar hidding/restoring into Xen to fix S3 w/ TXT (Resend)

["Wang, Shane" <shane.wang@xxxxxxxxx>]

OK. Then restoring DMAR is not necessary before S3.
But I am thinking whether we need to hide DMAR again after S3 resume.

Thanks.
Shane

Keir Fraser wrote on 2011-01-10:

> On 10/01/2011 03:32, "Wang, Shane" <shane.wang@xxxxxxxxx> wrote:
> 
>> Put the code for hidding and restoring DMAR table from tboot into
>> Xen in order to fix S3 broken issue with TXT launch.
> 
> We already do this in arch/x86/acpi/power.c:enter_state(). Since
> enter_state() is in the call stack of tboot_shutdown(), via
> tboot_sleep(), this patch is unnecessary. In fact
> acpi_dmar_reinstate() is not idempotent, so I actually think this patch takes 
> a reinstated DMAR and breaks its checksum!
> 
>  -- Keir
>  
>> Signed-off-by: Shane Wang <shane.wang@xxxxxxxxx>
>> 
>> diff -r 946d84529a07 xen/arch/x86/tboot.c
>> --- a/xen/arch/x86/tboot.c Sat Jan 08 11:07:18 2011 +0000
>> +++ b/xen/arch/x86/tboot.c Wed Jan 12 01:37:14 2011 +0800
>> @@ -352,6 +352,9 @@ void tboot_shutdown(uint32_t shutdown_ty
>> 
>>      /* if this is S3 then set regions to MAC */
>>      if ( shutdown_type == TB_SHUTDOWN_S3 ) {
>> +        /* restore DMAR table */
>> +        acpi_dmar_reinstate();
>> +
>>          /*
>>           * Xen regions for tboot to MAC
>>           */
>> @@ -484,6 +487,7 @@ int tboot_s3_resume(void)  int
>> tboot_s3_resume(void)  {
>>      vmac_t mac;
>> +    int ret = 0;
>> 
>>      if ( !tboot_in_measured_env() )
>>          return 0;
>> @@ -492,22 +496,30 @@ int tboot_s3_resume(void)
>>      tboot_gen_xenheap_integrity(g_tboot_shared->s3_key, &mac);
>>      printk("MAC for xenheap before S3 is: 0x%08"PRIx64"\n",
>>      xenheap_mac); printk("MAC for xenheap after S3 is:
>>      0x%08"PRIx64"\n", mac);
>> -    if ( mac != xenheap_mac )
>> -        return -1;
>> +    if ( mac != xenheap_mac ) {
>> +        ret = -1;
>> +        goto exit;
>> +    }
>> 
>>      tboot_gen_frametable_integrity(g_tboot_shared->s3_key, &mac);
>>      printk("MAC for frametable before S3 is: 0x%08"PRIx64"\n",
>>      frametable_mac); printk("MAC for frametable after S3 is:
>>      0x%08"PRIx64"\n", mac);
>> -    if ( mac != frametable_mac )
>> -        return -2;
>> +    if ( mac != frametable_mac ) {
>> +        ret = -2;
>> +        goto exit;
>> +    }
>> 
>>      tboot_gen_domain_integrity(g_tboot_shared->s3_key, &mac);
>>      printk("MAC for domains before S3 is: 0x%08"PRIx64"\n",
>>      domain_mac); printk("MAC for domains after S3 is:
>>      0x%08"PRIx64"\n", mac);
>> -    if ( mac != domain_mac )
>> -        return -3;
>> +    if ( mac != domain_mac ) {
>> +        ret = -3;
>> +        goto exit;
>> +    }
>> 
>> -    return 0;
>> +exit:
>> +    acpi_dmar_zap();
>> +    return ret;
>>  }
>>  
>>  /*
>



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