Re: [Qemu-devel] [PATCH v2 3/6] Support Physical Presence Interface Spec

[Stefan Berger <stefanb@linux.vnet.ibm.com>]

On 05/15/2015 11:13 AM, Igor Mammedov wrote:
>
>> +                Field(HIGH, AnyAcc, NoLock, Preserve) {
>> +                   SIG1, 32,
>> +                   SIZE, 16,
>> +                   CODE, 8,
>> +                   SUCC, 8,
>> +                   CODO, 8,
>> +                   RESP, 32
>> +                }
>> +                // Check signature and sufficient space
>> +                If (LAnd(
>> +                    LEqual(SIG1, TCG_MAGIC),
> using SIG1 seems to be redundant now, the same goes for BIOS part.
> Why just not drop it?


I would like to keep the signature as an indicator that the BIOS has 
initialized the memory. Would that be acceptable ? QEMU provides the 
ACPI, the BIOS is indep. of it and the OS only sees what QEMU has 
provided. The OS  wouldn't know whether there's a BIOS that supports it 
what the ACPI indicates.


>
>   }
> diff --git a/include/hw/acpi/tpm.h b/include/hw/acpi/tpm.h
> index 6d516c6..8d9c8dc 100644
> --- a/include/hw/acpi/tpm.h
> +++ b/include/hw/acpi/tpm.h
> @@ -31,4 +31,24 @@
>   
>   #define TPM2_START_METHOD_MMIO      6
>   
> +/*
> + * Physical Presence Interface -- shared with the BIOS
> + */
> +#define TCG_MAGIC 0x41504354
> +
> +#if 0
> +struct tpm_ppi {
> +    uint32_t sign1;          // TCG_MAGIC
> +    uint16_t  size;          // number of subsequent bytes for ACPI to access
> +    uint8_t  opcode;         // set by ACPI
> +    uint8_t  failure;        // set by BIOS (0 = success)
> +    uint8_t  recent_opcode;  // set by BIOS
> +    uint32_t response;       // set by BIOS
> +    uint8_t  next_step;      // BIOS only
> +    uint32_t sign2;          // TCG_MAGIC
> +} QEMU_PACKED;
> +#endif

I removed sign2 from the SeaBIOS code, so only 1 signature.

    Stefan