[SeaBIOS] TPM 2.0 with SeaBIOS

[Stefan Berger]

On 07/27/2018 07:43 PM, Kevin O'Connor wrote:
> On Sat, Jul 21, 2018 at 08:11:14PM +0200, Piotr Kubaj wrote:
>> Hi,
>>
>> I use SeaBIOS 1.11.2 as payload with 4.8-835-g113f670baa on ASUS KGPE-D16 board. I also have ASUS TPM-L R2.0 module with Infineon SLB9665 chip.
>>
>> TPM is correctly detected by both Linux and FreeBSD. It's also detected by coreboot in debug console. But SeaBIOS doesn't cooperate with it - there's no TPM menu.
>>
>> In serial console, I get:
>> TCGBIOS: Detected a TPM 1.2.
>> rsdp=0x000f1930
>> rsdt=0xbf4b9030
>> table(41504354)=0xbf4bf460
>> TCGBIOS: Starting with TPM_Startup(ST_CLEAR)
>> Return from tpm_simple_cmd(99, 1) = 1e
>> TCGBIOS: TPM malfunctioning (line 874).
>> Return from tpm_simple_cmd(73, 0) = 1e
>>
>> Note that SeaBIOS detects it as TPM 1.2, even though it's TPM 2.0.
> The error (0x1e) appears to be a TPM_BADTAG code.  That's probably
> because it's being treated as a TPM v1.2 instead of v2.0.
>
> Stefan and Stephen were recently looking at this - maybe they know why
> this occurred?

Obviously our algorithm to detect the TPM version by interface works for 
some interfaces correctly but not all of them. The only strategy I can 
suggest now is to add more debugging information into 
src/hw/tpm_drivers.c tis_get_tpm_version():


diff --git a/src/hw/tpm_drivers.c b/src/hw/tpm_drivers.c
index e4770b3..7ba89aa 100644
--- a/src/hw/tpm_drivers.c
+++ b/src/hw/tpm_drivers.c
@@ -144,12 +144,15 @@ static TPMVersion tis_get_tpm_version(void)
  {
      u32 reg = readl(TIS_REG(0, TIS_REG_IFACE_ID));

+    dprintf(DEBUG_tcg, "iface_id = 0x%x\n", reg);
      /*
       * FIFO interface as defined in TIS1.3 is active
       * Interface capabilities are defined in TIS_REG_INTF_CAPABILITY
       */
      if ((reg & 0xf) == 0xf) {
          reg = readl(TIS_REG(0, TIS_REG_INTF_CAPABILITY));
+
+        dprintf(DEBUG_tcg, "intf_capability = 0x%x\n", reg);
          /* Interface 1.3 for TPM 2.0 */
          if (((reg >> 28) & 0x7) == 3)
              return TPM_VERSION_2;


If you could please patch this in and show what it displays.

     Stefan

>
> -Kevin
>