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Re: [Qemu-devel] [PATCH v8 5/5] PoC: tpm: add ACPI memory clear interfac


From: Igor Mammedov
Subject: Re: [Qemu-devel] [PATCH v8 5/5] PoC: tpm: add ACPI memory clear interface
Date: Mon, 23 Jul 2018 13:08:45 +0200

On Tue, 17 Jul 2018 17:39:12 +0200
Marc-André Lureau <address@hidden> wrote:

> Hi
> 
> On Tue, Jul 17, 2018 at 9:57 AM, Igor Mammedov <address@hidden> wrote:
> > On Mon, 16 Jul 2018 14:59:48 +0200
> > Marc-André Lureau <address@hidden> 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". According
> >> to Laszlo, it's not so easy to implement in OVMF, he suggested to do
> >> it in qemu instead. It is relatively simple to implement in QEMU, but
> >> make this a proof-of-concept PATCH for discussion, since this is not
> >> a conventional approach.
> >>
> >> Signed-off-by: Marc-André Lureau <address@hidden>
> >> ---
> >>  hw/i386/acpi-build.c | 46 ++++++++++++++++++++++++++++++++++++++++++++
> >>  hw/tpm/tpm_ppi.c     | 25 ++++++++++++++++++++++++
> >>  docs/specs/tpm.txt   |  2 ++
> >>  hw/tpm/trace-events  |  3 +++
> >>  4 files changed, 76 insertions(+)
> >>
> >> diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
> >> index 882fc27846..7e3c217076 100644
> >> --- a/hw/i386/acpi-build.c
> >> +++ b/hw/i386/acpi-build.c
> >> @@ -1824,6 +1824,13 @@ build_tpm_ppi(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 + 0x200),
> >> +                                    0x1));
> >> +    field = aml_field("TPP3", AML_ANY_ACC, AML_NOLOCK, AML_PRESERVE);  
> >                                  ^^^ AML_BYTE_ACC  
> 
> ok
> 
> 
> >  
> >> +    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].
> >> @@ -2166,7 +2173,46 @@ build_tpm_ppi(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 */
> >> +            ifctx2 = aml_if(aml_equal(function, zero));
> >> +            {
> >> +                uint8_t byte_list[1] = { 0x03 };
> >> +                aml_append(ifctx2, aml_return(aml_buffer(1, 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/hw/tpm/tpm_ppi.c b/hw/tpm/tpm_ppi.c
> >> index 8b46b9dd4b..64e8d828e8 100644
> >> --- a/hw/tpm/tpm_ppi.c
> >> +++ b/hw/tpm/tpm_ppi.c
> >> @@ -16,8 +16,31 @@
> >>  #include "qapi/error.h"
> >>  #include "cpu.h"
> >>  #include "sysemu/memory_mapping.h"
> >> +#include "sysemu/reset.h"
> >>  #include "migration/vmstate.h"
> >>  #include "tpm_ppi.h"
> >> +#include "trace.h"
> >> +
> >> +static void tpm_ppi_reset(void *opaque)
> >> +{
> >> +    TPMPPI *tpmppi = opaque;
> >> +    char *ptr = memory_region_get_ram_ptr(&tpmppi->ram);
> >> +
> >> +    if (ptr[0x200] & 0x1) {
> >> +        GuestPhysBlockList guest_phys_blocks;
> >> +        GuestPhysBlock *block;
> >> +
> >> +        guest_phys_blocks_init(&guest_phys_blocks);
> >> +        guest_phys_blocks_append(&guest_phys_blocks);
> >> +        QTAILQ_FOREACH(block, &guest_phys_blocks.head, next) {
> >> +            trace_tpm_ppi_memset(block->host_addr,
> >> +                             block->target_end - block->target_start);
> >> +            memset(block->host_addr, 0,
> >> +                   block->target_end - block->target_start);
> >> +        }
> >> +        guest_phys_blocks_free(&guest_phys_blocks);
> >> +    }
> >> +}
> >>
> >>  bool tpm_ppi_init(TPMPPI *tpmppi, struct MemoryRegion *m,
> >>                    hwaddr addr, Object *obj, Error **errp)
> >> @@ -27,5 +50,7 @@ bool tpm_ppi_init(TPMPPI *tpmppi, struct MemoryRegion *m,
> >>      vmstate_register_ram(&tpmppi->ram, DEVICE(obj));
> >>
> >>      memory_region_add_subregion(m, addr, &tpmppi->ram);
> >> +    qemu_register_reset(tpm_ppi_reset, tpmppi);  
> > is it necessary,
> > shouldn't it be reset by bus initiated reset?  
> 
> There is no bus for CRB device (we could eventually move it to SYSBUS,
> but there was some complication with piix iirc).
> 
> Other than that, the role for BusClass.reset() isn't so clear to me,
> but it seems to be linked with the same qemu reset handler.

I'd suggest to drop qemu_register_reset() here, export tpm_ppi_reset()
and call it explicitly from tpm_crb_reset() and tpm_tis_reset() if
ppi is enabled.


> >> +
> >>      return true;
> >>  }
> >> diff --git a/docs/specs/tpm.txt b/docs/specs/tpm.txt
> >> index 16b210c1f2..9c44384315 100644
> >> --- a/docs/specs/tpm.txt
> >> +++ b/docs/specs/tpm.txt
> >> @@ -121,6 +121,8 @@ layout:
> >>   
> >> +----------+--------+--------+-------------------------------------------+
> >>   | next_step|   0x1  |  0x159 | Operation to execute after reboot by      
> >> |
> >>   |          |        |        | firmware. Used by firmware.               
> >> |
> >> + 
> >> +----------+--------+--------+-------------------------------------------+
> >> + | movv     |   0x1  |  0x200 | Memory overwrite variable                 
> >> |
> >>   
> >> +----------+--------+--------+-------------------------------------------+
> >>
> >>     The following values are supported for the 'func' field. They 
> >> correspond
> >> diff --git a/hw/tpm/trace-events b/hw/tpm/trace-events
> >> index 25bee0cecf..920d32ad55 100644
> >> --- a/hw/tpm/trace-events
> >> +++ b/hw/tpm/trace-events
> >> @@ -51,3 +51,6 @@ tpm_tis_mmio_write_init_abort(void) "Initiating abort"
> >>  tpm_tis_mmio_write_lowering_irq(void) "Lowering IRQ"
> >>  tpm_tis_mmio_write_data2send(uint32_t value, unsigned size) "Data to send 
> >> to TPM: 0x%08x (size=%d)"
> >>  tpm_tis_pre_save(uint8_t locty, uint32_t rw_offset) "locty: %d, rw_offset 
> >> = %u"
> >> +
> >> +# hw/tpm/tpm_ppi.c
> >> +tpm_ppi_memset(uint8_t *ptr, size_t size) "memset: %p %zu"  
> >
> >  
> 
> 
> 




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