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From: =?UTF-8?B?TWFyYy1BbmRyw6kgTHVyZWF1?= <marcandre.lureau@gmail.com>
Date: Thu, 21 Jun 2018 15:24:44 +0200
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Subject: Re: [Qemu-devel] [PATCH v3 4/4] tpm: add a fake ACPI memory clear
 interface
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To: Igor Mammedov <imammedo@redhat.com>, Laszlo Ersek <lersek@redhat.com>
Cc: Eduardo Habkost <ehabkost@redhat.com>, "Michael S. Tsirkin" <mst@redhat.com>, Stefan Berger <stefanb@linux.vnet.ibm.com>, QEMU <qemu-devel@nongnu.org>, Paolo Bonzini <pbonzini@redhat.com>, Richard Henderson <rth@twiddle.net>

Hi

On Thu, Jun 21, 2018 at 3:02 PM, Igor Mammedov <imammedo@redhat.com> wrote:
> On Tue, 15 May 2018 14:14:33 +0200
> Marc-Andr=C3=A9 Lureau <marcandre.lureau@redhat.com> wrote:
>
>> This allows to pass the last failing test from the Windows HLK TPM 2.0
>> TCG PPI 1.3 tests.
>>
>> The interface is described in the "TCG Platform Reset Attack
>> Mitigation Specification", chapter 6 "ACPI _DSM Function". Whether or
>> not we should have a real implementation remains an open question to me.
> might it cause security issues?

Good question. If the guest assumes success of this operation perhaps.
I'll check the spec.

> What are implications of faking it and how hard it's to implement thing
> per spec?

Laszlo answerd that in "[Qemu-devel] investigating TPM for
OVMF-on-QEMU"  2f2b) TCG Memory Clear Interface

>
>
>> Signed-off-by: Marc-Andr=C3=A9 Lureau <marcandre.lureau@redhat.com>
>> ---
>>  hw/i386/acpi-build.c | 9 +++++++++
>>  1 file changed, 9 insertions(+)
>>
>> diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
>> index 95be4f0710..392a1e50bd 100644
>> --- a/hw/i386/acpi-build.c
>> +++ b/hw/i386/acpi-build.c
>> @@ -2072,6 +2072,15 @@ build_tpm_ppi(Aml *dev)
>>              aml_append(ifctx, aml_return(aml_buffer(1, zerobyte)));
>>          }
>>          aml_append(method, ifctx);
>> +
>> +       /* dummy MOR Memory Clear for the sake of WLK PPI test */
>> +        ifctx =3D aml_if(
>> +            aml_equal(aml_arg(0),
>> +                      aml_touuid("376054ED-CC13-4675-901C-4756D7F2D45D"=
)));
>> +        {
>> +            aml_append(ifctx, aml_return(aml_int(0)));
>> +        }
>> +        aml_append(method, ifctx);
>>      }
>>      aml_append(dev, method);
>>  }
>
>



--=20
Marc-Andr=C3=A9 Lureau