Re: [Xen-devel] [PATCH][BIOS]Fix TPMD and QEMU connection

[Stefan Berger <stefanb@xxxxxxxxxx>]

xen-devel-bounces@xxxxxxxxxxxxxxxxxxx wrote on 12/19/2007
07:53:11 PM:

> Hi,
> 
> In HVM domain, MA_Transmit function in tcgbios sometimes become an
error
> (TCG_NO_RESPONSE). The cause of the error is not to make connection
of
> QEMU and TPMD instance within a timeout of MA_Transmit function.
> 
> Before the MA_Transmit function was called, the attached patch corrected
so
> that connection of QEMU and TPMD might be completed.
> 
> Signed-off-by: Kouichi YASAKI <yasaki.kouichi@xxxxxxxxxxxxxx>
> 
> Thanks
>   Kouichi YASAKI
> 
> diff -r d9ab9eb2bfee tools/ioemu/hw/tpm_tis.c
> --- a/tools/ioemu/hw/tpm_tis.c   Sat Dec 15 18:29:27 2007 +0000
> +++ b/tools/ioemu/hw/tpm_tis.c   Mon Dec 17 19:46:42 2007 +0900
> @@ -904,6 +904,10 @@ void tpm_tis_init(SetIRQFunc *set_irq, v
>      memset(s->buffer.buf,0,sizeof(s->buffer.buf));
>  
>      register_savevm("tpm-tis", 0, 1, tpm_save,
tpm_load, s);
> +
> +    while(!IS_COMM_WITH_VTPM(s)){
> +       open_vtpm_channel(s);
> +    }
>  }

I'll have a look at this. The problem probably stems
from the vTPM manager starting the vTPM up too late while qemu is already
up and running, so it's a timing problem between the two processes. I don't
think it should try to connect endlessly in a busy loop. At least there
should be a counter that tries this for maybe 5 times followed by a [u]sleep()
in the loop.

    int ctr = 0;
    while(!IS_COMM_WITH_VTPM(s) &&
ctr < 5){
       open_vtpm_channel(s);
       ctr ++;
       sleep(1);
    }


   Stefan

>  
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