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

[Stefan Berger]

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