Re: [Qemu-devel] [PATCH 1/5] tpm: Move getting TPM buffer size to backends

["Marc-André Lureau" <marcandre.lureau@redhat.com>]

On Mon, Nov 06, 2017 at 07:58:52PM -0500, Stefan Berger wrote:
> Rather than setting the size of the TPM buffer in the front-end,
> query the backend for the size of the buffer. In this patch we
> just move the hard-coded buffer size of 4096 to the backends.
> 
> Signed-off-by: Stefan Berger <stefanb@linux.vnet.ibm.com>
> ---
>  backends/tpm.c               |  9 +++++++++
>  hw/tpm/tpm_emulator.c        |  6 ++++++
>  hw/tpm/tpm_passthrough.c     |  6 ++++++
>  hw/tpm/tpm_tis.c             | 12 +++++++-----
>  include/sysemu/tpm_backend.h | 11 +++++++++++
>  5 files changed, 39 insertions(+), 5 deletions(-)
> 
> diff --git a/backends/tpm.c b/backends/tpm.c
> index 7777467..e7d0f9a 100644
> --- a/backends/tpm.c
> +++ b/backends/tpm.c
> @@ -139,6 +139,15 @@ TPMVersion tpm_backend_get_tpm_version(TPMBackend *s)
>      return k->get_tpm_version(s);
>  }
>  
> +uint32_t tpm_backend_get_buffer_size(TPMBackend *s)

We have a slight preference for size_t in qemu (even if underlying
protocol uses u32)

> +{
> +    TPMBackendClass *k = TPM_BACKEND_GET_CLASS(s);
> +
> +    assert(k->get_buffer_size);


No need to have assert here to be consitent with qemu code, however it
is nice to have a comment on the interface declaration instead.

(I considered all function pointers mandatory unless explicitely
marked optional, as in "tpm-be: update optional function pointers")

> +
> +    return k->get_buffer_size(s);
> +}
> +
>  TPMInfo *tpm_backend_query_tpm(TPMBackend *s)
>  {
>      TPMInfo *info = g_new0(TPMInfo, 1);
> diff --git a/hw/tpm/tpm_emulator.c b/hw/tpm/tpm_emulator.c
> index 24cb611..5a6107e 100644
> --- a/hw/tpm/tpm_emulator.c
> +++ b/hw/tpm/tpm_emulator.c
> @@ -356,6 +356,11 @@ static TPMVersion tpm_emulator_get_tpm_version(TPMBackend *tb)
>      return tpm_emu->tpm_version;
>  }
>  
> +static uint32_t tpm_emulator_get_buffer_size(TPMBackend *tb)
> +{
> +    return 4096;
> +}
> +
>  static int tpm_emulator_block_migration(TPMEmulator *tpm_emu)
>  {
>      Error *err = NULL;
> @@ -556,6 +561,7 @@ static void tpm_emulator_class_init(ObjectClass *klass, void *data)
>      tbc->get_tpm_established_flag = tpm_emulator_get_tpm_established_flag;
>      tbc->reset_tpm_established_flag = tpm_emulator_reset_tpm_established_flag;
>      tbc->get_tpm_version = tpm_emulator_get_tpm_version;
> +    tbc->get_buffer_size = tpm_emulator_get_buffer_size;
>      tbc->get_tpm_options = tpm_emulator_get_tpm_options;
>  
>      tbc->handle_request = tpm_emulator_handle_request;
> diff --git a/hw/tpm/tpm_passthrough.c b/hw/tpm/tpm_passthrough.c
> index 73554aa..7ff9249 100644
> --- a/hw/tpm/tpm_passthrough.c
> +++ b/hw/tpm/tpm_passthrough.c
> @@ -199,6 +199,11 @@ static TPMVersion tpm_passthrough_get_tpm_version(TPMBackend *tb)
>      return tpm_pt->tpm_version;
>  }
>  
> +static uint32_t tpm_passthrough_get_buffer_size(TPMBackend *tb)
> +{
> +    return 4096;
> +}
> +
>  /*
>   * Unless path or file descriptor set has been provided by user,
>   * determine the sysfs cancel file following kernel documentation
> @@ -354,6 +359,7 @@ static void tpm_passthrough_class_init(ObjectClass *klass, void *data)
>      tbc->reset_tpm_established_flag =
>          tpm_passthrough_reset_tpm_established_flag;
>      tbc->get_tpm_version = tpm_passthrough_get_tpm_version;
> +    tbc->get_buffer_size = tpm_passthrough_get_buffer_size;
>      tbc->get_tpm_options = tpm_passthrough_get_tpm_options;
>      tbc->handle_request = tpm_passthrough_handle_request;
>  }
> diff --git a/hw/tpm/tpm_tis.c b/hw/tpm/tpm_tis.c
> index cc32fcd..a3df40f 100644
> --- a/hw/tpm/tpm_tis.c
> +++ b/hw/tpm/tpm_tis.c
> @@ -88,6 +88,8 @@ typedef struct TPMState {
>  
>      TPMBackend *be_driver;
>      TPMVersion be_tpm_version;
> +
> +    uint32_t be_buffer_size;
>  } TPMState;
>  
>  #define TPM(obj) OBJECT_CHECK(TPMState, (obj), TYPE_TPM_TIS)
> @@ -977,10 +979,9 @@ static int tpm_tis_do_startup_tpm(TPMState *s)
>      return tpm_backend_startup_tpm(s->be_driver);
>  }
>  
> -static void tpm_tis_realloc_buffer(TPMSizedBuffer *sb)
> +static void tpm_tis_realloc_buffer(TPMSizedBuffer *sb,
> +                                   uint32_t wanted_size)
>  {
> -    size_t wanted_size = 4096; /* Linux tpm.c buffer size */
> -
>      if (sb->size != wanted_size) {
>          sb->buffer = g_realloc(sb->buffer, wanted_size);
>          sb->size = wanted_size;
> @@ -1007,6 +1008,7 @@ static void tpm_tis_reset(DeviceState *dev)
>      int c;
>  
>      s->be_tpm_version = tpm_backend_get_tpm_version(s->be_driver);
> +    s->be_buffer_size = tpm_backend_get_buffer_size(s->be_driver);
>  
>      tpm_backend_reset(s->be_driver);
>  
> @@ -1033,9 +1035,9 @@ static void tpm_tis_reset(DeviceState *dev)
>          s->loc[c].state = TPM_TIS_STATE_IDLE;
>  
>          s->loc[c].w_offset = 0;
> -        tpm_tis_realloc_buffer(&s->loc[c].w_buffer);
> +        tpm_tis_realloc_buffer(&s->loc[c].w_buffer, s->be_buffer_size);
>          s->loc[c].r_offset = 0;
> -        tpm_tis_realloc_buffer(&s->loc[c].r_buffer);
> +        tpm_tis_realloc_buffer(&s->loc[c].r_buffer, s->be_buffer_size);
>      }
>  
>      tpm_tis_do_startup_tpm(s);
> diff --git a/include/sysemu/tpm_backend.h b/include/sysemu/tpm_backend.h
> index 590e8b4..d23cef2 100644
> --- a/include/sysemu/tpm_backend.h
> +++ b/include/sysemu/tpm_backend.h
> @@ -80,6 +80,7 @@ struct TPMBackendClass {
>      int (*reset_tpm_established_flag)(TPMBackend *t, uint8_t locty);
>  
>      TPMVersion (*get_tpm_version)(TPMBackend *t);
> +    uint32_t (*get_buffer_size)(TPMBackend *t);
>  
>      TpmTypeOptions *(*get_tpm_options)(TPMBackend *t);
>  
> @@ -183,6 +184,16 @@ int tpm_backend_reset_tpm_established_flag(TPMBackend *s, uint8_t locty);
>  TPMVersion tpm_backend_get_tpm_version(TPMBackend *s);
>  
>  /**
> + * tpm_backend_get_buffer_size:
> + * @s: the backend to call into
> + *
> + * Get the TPM's buffer size.
> + *
> + * Returns buffer size.
> + */
> +uint32_t tpm_backend_get_buffer_size(TPMBackend *s);
> +
> +/**
>   * tpm_backend_query_tpm:
>   * @s: the backend
>   *
> -- 
> 2.5.5
> 
> 

Looks good to me otherwise,

Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>