Re: [Qemu-devel] [PATCH v8 2/5] tpm: implement virtual memory device for TPM PPI

[Igor Mammedov]

On Tue, 17 Jul 2018 12:22:49 +0200
Marc-André Lureau <address@hidden> wrote:

> On Tue, Jul 17, 2018 at 9:59 AM, Igor Mammedov <address@hidden> wrote:
> > On Mon, 16 Jul 2018 16:56:36 +0200
> > Marc-André Lureau <address@hidden> wrote:
> >  
> >> Hi
> >>
> >> On Mon, Jul 16, 2018 at 4:44 PM, Igor Mammedov <address@hidden> wrote:  
> >> > On Mon, 16 Jul 2018 14:59:45 +0200
> >> > Marc-André Lureau <address@hidden> wrote:
> >> >  
> >> >> From: Stefan Berger <address@hidden>
> >> >>
> >> >> Implement a virtual memory device for the TPM Physical Presence 
> >> >> interface.
> >> >> The memory is located at 0xFED45000 and used by ACPI to send messages 
> >> >> to the
> >> >> firmware (BIOS) and by the firmware to provide parameters for each one 
> >> >> of
> >> >> the supported codes.  
> >> > it doesn't implement anything, maybe something like this would be better?
> >> >
> >> > tpm: allocate/map buffer for TPM Physical Presence interface
> >> >
> >> > ...
> >> >  
> >> >>
> >> >> This device should be used by all TPM interfaces on x86 and can be added
> >> >> by calling tpm_ppi_init_io().  
> >> > Did you mean:
> >> >  This *interface* should be used by all TPM *devices* on x86 and can be 
> >> > added
> >> >  by calling tpm_ppi_init_io().
> >> >
> >> >  
> >> >> Note: bios_linker cannot be used to allocate the PPI memory region,
> >> >> since the reserved memory should stay stable across reboots, and might
> >> >> be needed before the ACPI tables are installed.
> >> >>
> >> >> Signed-off-by: Stefan Berger <address@hidden>
> >> >> Signed-off-by: Marc-André Lureau <address@hidden>
> >> >> ---
> >> >>  hw/tpm/tpm_ppi.h      | 26 ++++++++++++++++++++++++++
> >> >>  include/hw/acpi/tpm.h |  6 ++++++
> >> >>  hw/tpm/tpm_crb.c      |  8 ++++++++
> >> >>  hw/tpm/tpm_ppi.c      | 31 +++++++++++++++++++++++++++++++
> >> >>  hw/tpm/tpm_tis.c      |  8 ++++++++
> >> >>  hw/tpm/Makefile.objs  |  1 +
> >> >>  6 files changed, 80 insertions(+)
> >> >>  create mode 100644 hw/tpm/tpm_ppi.h
> >> >>  create mode 100644 hw/tpm/tpm_ppi.c
> >> >>
> >> >> diff --git a/hw/tpm/tpm_ppi.h b/hw/tpm/tpm_ppi.h
> >> >> new file mode 100644
> >> >> index 0000000000..f6458bf87e
> >> >> --- /dev/null
> >> >> +++ b/hw/tpm/tpm_ppi.h
> >> >> @@ -0,0 +1,26 @@
> >> >> +/*
> >> >> + * TPM Physical Presence Interface
> >> >> + *
> >> >> + * Copyright (C) 2018 IBM Corporation
> >> >> + *
> >> >> + * Authors:
> >> >> + *  Stefan Berger    <address@hidden>
> >> >> + *
> >> >> + * This work is licensed under the terms of the GNU GPL, version 2 or 
> >> >> later.
> >> >> + * See the COPYING file in the top-level directory.
> >> >> + */
> >> >> +#ifndef TPM_TPM_PPI_H
> >> >> +#define TPM_TPM_PPI_H
> >> >> +
> >> >> +#include "hw/acpi/tpm.h"
> >> >> +#include "exec/address-spaces.h"
> >> >> +
> >> >> +typedef struct TPMPPI {
> >> >> +    MemoryRegion ram;
> >> >> +    uint8_t buf[TPM_PPI_ADDR_SIZE];
> >> >> +} TPMPPI;
> >> >> +
> >> >> +bool tpm_ppi_init(TPMPPI *tpmppi, struct MemoryRegion *m,
> >> >> +                  hwaddr addr, Object *obj, Error **errp);
> >> >> +
> >> >> +#endif /* TPM_TPM_PPI_H */
> >> >> diff --git a/include/hw/acpi/tpm.h b/include/hw/acpi/tpm.h
> >> >> index 3580ffd50c..b8796df916 100644
> >> >> --- a/include/hw/acpi/tpm.h
> >> >> +++ b/include/hw/acpi/tpm.h
> >> >> @@ -188,4 +188,10 @@ REG32(CRB_DATA_BUFFER, 0x80)
> >> >>  #define TPM2_START_METHOD_MMIO      6
> >> >>  #define TPM2_START_METHOD_CRB       7
> >> >>
> >> >> +/*
> >> >> + * Physical Presence Interface
> >> >> + */
> >> >> +#define TPM_PPI_ADDR_SIZE           0x400
> >> >> +#define TPM_PPI_ADDR_BASE           0xFED45000
> >> >> +
> >> >>  #endif /* HW_ACPI_TPM_H */
> >> >> diff --git a/hw/tpm/tpm_crb.c b/hw/tpm/tpm_crb.c
> >> >> index d5b0ac5920..b243222fd6 100644
> >> >> --- a/hw/tpm/tpm_crb.c
> >> >> +++ b/hw/tpm/tpm_crb.c
> >> >> @@ -29,6 +29,7 @@
> >> >>  #include "sysemu/reset.h"
> >> >>  #include "tpm_int.h"
> >> >>  #include "tpm_util.h"
> >> >> +#include "tpm_ppi.h"
> >> >>  #include "trace.h"
> >> >>
> >> >>  typedef struct CRBState {
> >> >> @@ -43,6 +44,7 @@ typedef struct CRBState {
> >> >>      size_t be_buffer_size;
> >> >>
> >> >>      bool ppi_enabled;
> >> >> +    TPMPPI ppi;
> >> >>  } CRBState;
> >> >>
> >> >>  #define CRB(obj) OBJECT_CHECK(CRBState, (obj), TYPE_TPM_CRB)
> >> >> @@ -294,6 +296,12 @@ static void tpm_crb_realize(DeviceState *dev, 
> >> >> Error **errp)
> >> >>      memory_region_add_subregion(get_system_memory(),
> >> >>          TPM_CRB_ADDR_BASE + sizeof(s->regs), &s->cmdmem);
> >> >>
> >> >> +    if (s->ppi_enabled &&
> >> >> +        !tpm_ppi_init(&s->ppi, get_system_memory(),
> >> >> +                      TPM_PPI_ADDR_BASE, OBJECT(s), errp)) {
> >> >> +        return;
> >> >> +    }
> >> >> +
> >> >>      qemu_register_reset(tpm_crb_reset, dev);
> >> >>  }
> >> >>
> >> >> diff --git a/hw/tpm/tpm_ppi.c b/hw/tpm/tpm_ppi.c
> >> >> new file mode 100644
> >> >> index 0000000000..8b46b9dd4b
> >> >> --- /dev/null
> >> >> +++ b/hw/tpm/tpm_ppi.c
> >> >> @@ -0,0 +1,31 @@
> >> >> +/*
> >> >> + * tpm_ppi.c - TPM Physical Presence Interface
> >> >> + *
> >> >> + * Copyright (C) 2018 IBM Corporation
> >> >> + *
> >> >> + * Authors:
> >> >> + *  Stefan Berger <address@hidden>
> >> >> + *
> >> >> + * This work is licensed under the terms of the GNU GPL, version 2 or 
> >> >> later.
> >> >> + * See the COPYING file in the top-level directory.
> >> >> + *
> >> >> + */
> >> >> +
> >> >> +#include "qemu/osdep.h"
> >> >> +
> >> >> +#include "qapi/error.h"
> >> >> +#include "cpu.h"
> >> >> +#include "sysemu/memory_mapping.h"
> >> >> +#include "migration/vmstate.h"
> >> >> +#include "tpm_ppi.h"
> >> >> +
> >> >> +bool tpm_ppi_init(TPMPPI *tpmppi, struct MemoryRegion *m,
> >> >> +                  hwaddr addr, Object *obj, Error **errp)
> >> >> +{
> >> >> +    memory_region_init_ram_device_ptr(&tpmppi->ram, obj, "tpm-ppi",
> >> >> +                                      TPM_PPI_ADDR_SIZE, tpmppi->buf); 
> >> >>  
> >> > why use buf and not a plain ram memory region?  
> >>
> >> It shouldn't be treated as regular RAM. (for example when iterating
> >> guest_phys_blocks for dump or memory clear in last patch)  
> > why it shouldn't, I'd think having ppi flags in dump would be useful  
> 
> We don't dump device memory.
> 
> > and why it shouldn't be cleared on reset along with all other ram?  
> 
> It's a device memory, not system memory. The spec talks only about
> system memory RAM, and Stefan also mentioned that we should not touch
> device/tpm RAM in previous review.
ok


> However, we may clear the MOR bit after reset (shown in Figure 2 in
> the spec - "the MemoryOverwriteRequestControl EFI variable described
> in Section 5 can be updated to clear the MOR bit after secrets have
> been removed from memory")
Also spec talks about MOR flags being saved in nonvolatile memory
so it would survive S4/S5 states. It's not the case with this
series but we probably should care since backend for ram/nvdimm
could be a persistent file.

Interesting, what should we do in case of nvdimm if it holds
an image of OS and aren't supposed to be cleared on reboot when
platform still sees it as part of RAM?

> 
> >>  
> >> >  
> >> >> +    vmstate_register_ram(&tpmppi->ram, DEVICE(obj));
> >> >> +
> >> >> +    memory_region_add_subregion(m, addr, &tpmppi->ram);
> >> >> +    return true;
> >> >> +}
> >> >> diff --git a/hw/tpm/tpm_tis.c b/hw/tpm/tpm_tis.c
> >> >> index d9ddf9b723..70432ffe8b 100644
> >> >> --- a/hw/tpm/tpm_tis.c
> >> >> +++ b/hw/tpm/tpm_tis.c
> >> >> @@ -31,6 +31,7 @@
> >> >>  #include "sysemu/tpm_backend.h"
> >> >>  #include "tpm_int.h"
> >> >>  #include "tpm_util.h"
> >> >> +#include "tpm_ppi.h"
> >> >>  #include "trace.h"
> >> >>
> >> >>  #define TPM_TIS_NUM_LOCALITIES      5     /* per spec */
> >> >> @@ -83,6 +84,7 @@ typedef struct TPMState {
> >> >>      size_t be_buffer_size;
> >> >>
> >> >>      bool ppi_enabled;
> >> >> +    TPMPPI ppi;
> >> >>  } TPMState;
> >> >>
> >> >>  #define TPM(obj) OBJECT_CHECK(TPMState, (obj), TYPE_TPM_TIS)
> >> >> @@ -979,6 +981,12 @@ static void tpm_tis_realizefn(DeviceState *dev, 
> >> >> Error **errp)
> >> >>
> >> >>      memory_region_add_subregion(isa_address_space(ISA_DEVICE(dev)),
> >> >>                                  TPM_TIS_ADDR_BASE, &s->mmio);
> >> >> +
> >> >> +    if (s->ppi_enabled &&
> >> >> +        !tpm_ppi_init(&s->ppi, isa_address_space(ISA_DEVICE(dev)),
> >> >> +                      TPM_PPI_ADDR_BASE, OBJECT(s), errp)) {
> >> >> +        return;
> >> >> +    }
> >> >>  }
> >> >>
> >> >>  static void tpm_tis_initfn(Object *obj)
> >> >> diff --git a/hw/tpm/Makefile.objs b/hw/tpm/Makefile.objs
> >> >> index 1dc9f8bf2c..700c878622 100644
> >> >> --- a/hw/tpm/Makefile.objs
> >> >> +++ b/hw/tpm/Makefile.objs
> >> >> @@ -1,4 +1,5 @@
> >> >>  common-obj-y += tpm_util.o
> >> >> +obj-y += tpm_ppi.o
> >> >>  common-obj-$(CONFIG_TPM_TIS) += tpm_tis.o
> >> >>  common-obj-$(CONFIG_TPM_CRB) += tpm_crb.o
> >> >>  common-obj-$(CONFIG_TPM_PASSTHROUGH) += tpm_passthrough.o  
> >> >
> >> >  
> >>
> >>
> >>  
> >  
> 
> 
>