Hi
On Wed, Jan 9, 2019 at 6:47 PM Michael S. Tsirkin <m...@redhat.com> wrote:
>
> On Wed, Jan 09, 2019 at 12:29:01PM +0400, Marc-André Lureau wrote:
> > The interface is described in the "TCG Platform Reset Attack
> > Mitigation Specification", chapter 6 "ACPI _DSM Function". According
> > to Laszlo, it's not so easy to implement in OVMF, he suggested to do
> > it in qemu instead.
> >
> > See specification documentation for more details, and next commit for
> > memory clear on reset handling.
> >
> > Signed-off-by: Marc-André Lureau <marcandre.lur...@redhat.com>
> > ---
> > hw/acpi/tpm.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++
> > docs/specs/tpm.txt | 2 ++
> > 2 files changed, 50 insertions(+)
> >
> > diff --git a/hw/acpi/tpm.c b/hw/acpi/tpm.c
> > index fee9490306..61da1de97b 100644
> > --- a/hw/acpi/tpm.c
> > +++ b/hw/acpi/tpm.c
> > @@ -53,6 +53,16 @@ void tpm_build_ppi_acpi(TPMIf *tpm, Aml *dev)
> > pprq = aml_name("PPRQ");
> > pprm = aml_name("PPRM");
> >
> > + aml_append(dev,
> > + aml_operation_region(
> > + "TPP3", AML_SYSTEM_MEMORY,
> > + aml_int(TPM_PPI_ADDR_BASE +
> > + 0x15a /* movv, docs/specs/tpm.txt */),
> > + 0x1
> > ));
> > + field = aml_field("TPP3", AML_BYTE_ACC, AML_NOLOCK, AML_PRESERVE);
> > + aml_append(field, aml_named_field("MOVV", 8));
> > + aml_append(dev, field);
> > +
> > /*
> > * DerefOf in Windows is broken with SYSTEM_MEMORY. Use a dynamic
> > * operation region inside of a method for getting FUNC[op].
> > @@ -395,6 +405,44 @@ void tpm_build_ppi_acpi(TPMIf *tpm, Aml *dev)
> > aml_append(ifctx, aml_return(aml_buffer(1, zerobyte)));
> > }
> > aml_append(method, ifctx);
> > +
> > + ifctx = aml_if(
> > + aml_equal(uuid,
> > + aml_touuid("376054ED-CC13-4675-901C-4756D7F2D45D")));
> > + {
> > + /* standard DSM query function */
>
> refer to spec chapter here?
Yes, we could add a code comment such as:
/* "TCG Platform Reset Attack Mitigation Specification", chapter 6
"ACPI _DSM Function" */
>
> > + ifctx2 = aml_if(aml_equal(function, zero));
> > + {
> > + uint8_t byte_list[1] = { 0x03 };
>
> and explain 3 above?
/* functions 1-2 are supported */
>
> > + aml_append(ifctx2, aml_return(aml_buffer(1
>
> 1 -> sizeof(byte_list)?
ok
>
> > + , byte_list)));
> > + }
> > + aml_append(ifctx, ifctx2);
> > +
> > + /*
> > + * TCG Platform Reset Attack Mitigation Specification 1.0 Ch.6
> > + *
> > + * Arg 2 (Integer): Function Index = 1
> > + * Arg 3 (Package): Arguments = Package: Type: Integer
> > + * Operation Value of the Request
> > + * Returns: Type: Integer
> > + * 0: Success
> > + * 1: General Failure
> > + */
> > + ifctx2 = aml_if(aml_equal(function, one));
> > + {
> > + aml_append(ifctx2,
> > + aml_store(aml_derefof(aml_index(arguments,
> > zero)),
> > + op));
> > + {
> > + aml_append(ifctx2, aml_store(op, aml_name("MOVV")));
> > +
> > + /* 0: success */
> > + aml_append(ifctx2, aml_return(zero));
> > + }
> > + }
> > + aml_append(ifctx, ifctx2);
> > + }
> > + aml_append(method, ifctx);
> > }
> > aml_append(dev, method);
> > }
> > diff --git a/docs/specs/tpm.txt b/docs/specs/tpm.txt
> > index 424d1511fc..5d8c26b1ad 100644
> > --- a/docs/specs/tpm.txt
> > +++ b/docs/specs/tpm.txt
> > @@ -135,6 +135,8 @@ layout:
> > +----------+--------+--------+-------------------------------------------+
> > | next_step| 0x1 | 0x159 | Operation to execute after reboot by |
> > | | | | firmware. Used by firmware. |
> > + +----------+--------+--------+-------------------------------------------+
> > + | movv | 0x1 | 0x15a | Memory overwrite variable |
> > +----------+--------+--------+-------------------------------------------+
> >
> > The following values are supported for the 'func' field. They correspond
> > --
> > 2.20.1.2.gb21ebb671b
>
--
Marc-André Lureau
