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

[Michael S. Tsirkin]

On Tue, Nov 09, 2021 at 09:26:46AM -0500, Stefan Berger wrote:
> 
> 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.
> 
> 

ok

> > 
> > > 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.


the spec says UID is unique for all
devices with a given CID or HID. Does this mean just HID is used
if no CID? Or that all devices without CID must have unique UIDs?

I think the former but just making sure.

> 
> > >                   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