Re: [PATCH v2 2/3] acpi: tpm: Add missing device identification objects

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

On 11/9/21 09:20, Michael S. Tsirkin wrote:
> On Tue, Nov 09, 2021 at 09:01:51AM -0500, Stefan Berger wrote:
>> Add missing device identification objects _STR and _UID. They will appear
>> as files 'description' and 'uid' under Linux sysfs.
>>
>> Cc: Shannon Zhao <shannon.zhaosl@gmail.com>
>> Cc: Michael S. Tsirkin <mst@redhat.com>
>> Cc: Igor Mammedov <imammedo@redhat.com>
>> Cc: Ani Sinha <ani@anisinha.ca>
>> Fixes: https://gitlab.com/qemu-project/qemu/-/issues/708
>> Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
> Do you want this in 6.2?

Yes.


>
>> ---
>>   hw/arm/virt-acpi-build.c | 1 +
>>   hw/i386/acpi-build.c     | 8 ++++++++
>>   2 files changed, 9 insertions(+)
>>
>> diff --git a/hw/arm/virt-acpi-build.c b/hw/arm/virt-acpi-build.c
>> index 674f902652..09456424aa 100644
>> --- a/hw/arm/virt-acpi-build.c
>> +++ b/hw/arm/virt-acpi-build.c
>> @@ -228,6 +228,7 @@ static void acpi_dsdt_add_tpm(Aml *scope, VirtMachineState *vms)
>>   
>>       Aml *dev = aml_device("TPM0");
>>       aml_append(dev, aml_name_decl("_HID", aml_string("MSFT0101")));
>> +    aml_append(dev, aml_name_decl("_STR", aml_string("TPM 2.0 Device")));
>>       aml_append(dev, aml_name_decl("_UID", aml_int(0)));
>>   
>>       Aml *crs = aml_resource_template();
>> diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
>> index a3ad6abd33..5bd2160a89 100644
>> --- a/hw/i386/acpi-build.c
>> +++ b/hw/i386/acpi-build.c
>> @@ -1808,11 +1808,15 @@ build_dsdt(GArray *table_data, BIOSLinker *linker,
>>                       dev = aml_device("TPM");
>>                       aml_append(dev, aml_name_decl("_HID",
>>                                                     aml_string("MSFT0101")));
>> +                    aml_append(dev,
>> +                               aml_name_decl("_STR",
>> +                                             aml_string("TPM 2.0 Device")));
>
> When we support more versions, won't this make us
> do annoying tricks to say so in the string?
> Why not just "TPM device" to future-proof it?

I am not sure what other version there will be and I haven't seen any 
other descriptions than the one reported here:

https://gitlab.com/qemu-project/qemu/-/issues/708

That's why I took TPM 2.0 device. My TPM 1.2 machine doesn't report it 
for a TPM 1.2.



>
>> haven                 } else {
>>                       dev = aml_device("ISA.TPM");
>>                       aml_append(dev, aml_name_decl("_HID",
>>                                                     aml_eisaid("PNP0C31")));
>>                   }
>> +                aml_append(dev, aml_name_decl("_UID", aml_int(1)));
>>
> The ACPI spec mentions also matching on _CID.
"6.1.2 _CID (Compatible ID)
This optional object is used to supply OSPM with a device?s Plug and 
Play-Compatible Device ID. Use _CID

objects when a device has no other defined hardware standard method to 
report its compatible IDs"


6.1.12 _UID (Unique ID)
This object provides OSPM with a logical device ID that does not change 
across reboots. This object is
optional, but is required when the device has no other way to report a 
persistent unique device ID. The
_UID must be unique across all devices with either a common _HID or _CID.


Is _CID a must-have for TPM now? We have _HID.


>    
>>                   aml_append(dev, aml_name_decl("_STA", aml_int(0xF)));
>>                   crs = aml_resource_template();
>> @@ -1840,6 +1844,8 @@ build_dsdt(GArray *table_data, BIOSLinker *linker,
>>       if (TPM_IS_CRB(tpm)) {
>>           dev = aml_device("TPM");
>>           aml_append(dev, aml_name_decl("_HID", aml_string("MSFT0101")));
>> +        aml_append(dev, aml_name_decl("_STR",
>> +                                      aml_string("TPM 2.0 Device")));
>>           crs = aml_resource_template();
>>           aml_append(crs, aml_memory32_fixed(TPM_CRB_ADDR_BASE,
>>                                              TPM_CRB_ADDR_SIZE, AML_READ_WRITE));
>> @@ -1847,6 +1853,8 @@ build_dsdt(GArray *table_data, BIOSLinker *linker,
>>   
>>           aml_append(dev, aml_name_decl("_STA", aml_int(0xf)));
>>   
>> +        aml_append(dev, aml_name_decl("_UID", aml_int(1)));
>> +
>>           tpm_build_ppi_acpi(tpm, dev);
>>   
>>           aml_append(sb_scope, dev);
>> -- 
>> 2.31.1