Re: [Qemu-devel] [PATCH v5 4/4] acpi: build TPM Physical Presence interface

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

On 06/27/2018 09:19 AM, Igor Mammedov wrote:
> On Tue, 26 Jun 2018 14:23:43 +0200
> Marc-André Lureau <marcandre.lureau@redhat.com> wrote:
>
>> From: Stefan Berger <stefanb@linux.vnet.ibm.com>
>>
>> The TPM Physical Presence interface consists of an ACPI part, a shared
>> memory part, and code in the firmware. Users can send messages to the
>> firmware by writing a code into the shared memory through invoking the
>> ACPI code. When a reboot happens, the firmware looks for the code and
>> acts on it by sending sequences of commands to the TPM.
>>
>> This patch adds the ACPI code. It is similar to the one in EDK2 but doesn't
>> assume that SMIs are necessary to use. It uses a similar datastructure for
>> the shared memory as EDK2 does so that EDK2 and SeaBIOS could both make use
>> of it. I extended the shared memory data structure with an array of 256
>> bytes, one for each code that could be implemented. The array contains
>> flags describing the individual codes. This decouples the ACPI implementation
>> from the firmware implementation.
>>
>> The underlying TCG specification is accessible from the following page.
>>
>> https://trustedcomputinggroup.org/tcg-physical-presence-interface-specification/
>>
>> This patch implements version 1.30.
> I've made several suggestions below how to improve aml part of patch a bit,
> will review v6 once it's done
> /hopefully it would be more readable, considering that ASM language is horrible to begin with/
>
>> Signed-off-by: Stefan Berger <stefanb@linux.vnet.ibm.com>
>>
>> ---
>>
>> v6:
>>   - more code documentation (Marc-André)
>>   - use some explicit named variables to ease reading (Marc-André)
>>   - use fixed size fields/memory regions, remove PPI struct (Marc-André)
>>   - only add PPI ACPI methods if PPI is enabled (Marc-André)
>>   - document the qemu/firmware ACPI memory region (Stefan)
>>
>> v5 (Marc-André):
>>   - /struct tpm_ppi/struct TPMPPIData
>>
>> v4 (Marc-André):
>>   - replace 'DerefOf (FUNC [N])' with a function, to fix Windows ACPI
>>      handling.
>>   - replace 'return Package (..) {} ' with scoped variables, to fix
>>     Windows ACPI handling.
>>
>> v3:
>>   - add support for PPI to CRB
>>   - split up OperationRegion TPPI into two parts, one containing
>>     the registers (TPP1) and the other one the flags (TPP2); switched
>>     the order of the flags versus registers in the code
>>   - adapted ACPI code to small changes to the array of flags where
>>     previous flag 0 was removed and now shifting right wasn't always
>>     necessary anymore
>>
>> v2:
>>   - get rid of FAIL variable; function 5 was using it and always
>>     returns 0; the value is related to the ACPI function call not
>>     a possible failure of the TPM function call.
>>   - extend shared memory data structure with per-opcode entries
>>     holding flags and use those flags to determine what to return
>>     to caller
>>   - implement interface version 1.3
>> ---
>>   include/hw/acpi/tpm.h |   8 +
>>   hw/i386/acpi-build.c  | 423 +++++++++++++++++++++++++++++++++++++++++-
>>   docs/specs/tpm.txt    |  79 ++++++++
>>   3 files changed, 509 insertions(+), 1 deletion(-)
>>
>> diff --git a/include/hw/acpi/tpm.h b/include/hw/acpi/tpm.h
>> index f79d68a77a..e0bd07862e 100644
>> --- a/include/hw/acpi/tpm.h
>> +++ b/include/hw/acpi/tpm.h
>> @@ -196,4 +196,12 @@ REG32(CRB_DATA_BUFFER, 0x80)
>>   #define TPM_PPI_VERSION_NONE        0
>>   #define TPM_PPI_VERSION_1_30        1
>>   
>> +/* whether function is blocked by BIOS settings; bits 0, 1, 2 */
>> +#define TPM_PPI_FUNC_NOT_IMPLEMENTED     (0 << 0)
>> +#define TPM_PPI_FUNC_BIOS_ONLY           (1 << 0)
>> +#define TPM_PPI_FUNC_BLOCKED             (2 << 0)
>> +#define TPM_PPI_FUNC_ALLOWED_USR_REQ     (3 << 0)
>> +#define TPM_PPI_FUNC_ALLOWED_USR_NOT_REQ (4 << 0)
>> +#define TPM_PPI_FUNC_MASK                (7 << 0)
>> +
>>   #endif /* HW_ACPI_TPM_H */
>> diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
>> index d9320845ed..d815af4eef 100644
>> --- a/hw/i386/acpi-build.c
>> +++ b/hw/i386/acpi-build.c
>> @@ -43,6 +43,7 @@
>>   #include "hw/acpi/memory_hotplug.h"
>>   #include "sysemu/tpm.h"
>>   #include "hw/acpi/tpm.h"
>> +#include "hw/tpm/tpm_ppi.h"
>>   #include "hw/acpi/vmgenid.h"
>>   #include "sysemu/tpm_backend.h"
>>   #include "hw/timer/mc146818rtc_regs.h"
>> @@ -1789,6 +1790,421 @@ static Aml *build_q35_osc_method(void)
>>       return method;
>>   }
>>   
>> +static void
>> +build_tpm_ppi(Aml *dev)
>> +{
>> +    Aml *method, *name, *field, *ifctx, *ifctx2, *ifctx3, *pak;
>> +    int i;
>> +
>> +    if (!object_property_get_bool(OBJECT(tpm_find()), "ppi", &error_abort)) {
> if tpm_find() == NULL -> BAAM???

This function wouldn't be called if there's no TPM.