Re: [PATCH v8 4/6] tpm_spapr: Support suspend and resume

[Marc-André Lureau]

Hi

On Wed, Jan 8, 2020 at 8:14 PM Stefan Berger <address@hidden> wrote:
>
> From: Stefan Berger <address@hidden>
>
> Extend the tpm_spapr frontend with VM suspend and resume support.
>
> Signed-off-by: Stefan Berger <address@hidden>
> ---
>  hw/tpm/tpm_spapr.c  | 67 ++++++++++++++++++++++++++++++++++++++++++++-
>  hw/tpm/trace-events |  2 ++
>  2 files changed, 68 insertions(+), 1 deletion(-)
>
> diff --git a/hw/tpm/tpm_spapr.c b/hw/tpm/tpm_spapr.c
> index ab184fbb82..cf5c7851e7 100644
> --- a/hw/tpm/tpm_spapr.c
> +++ b/hw/tpm/tpm_spapr.c
> @@ -76,6 +76,9 @@ typedef struct {
>
>      unsigned char buffer[TPM_SPAPR_BUFFER_MAX];
>
> +    uint32_t numbytes; /* number of bytes in suspend_buffer */
> +    unsigned char *suspend_buffer;

Why do you need a copy suspend_buffer? Why not use and save buffer[] directly?

Also numbytes wouldn't be necessary, you would just need a bool flag
to say if the request_completed is pending.

> +
>      TPMBackendCmd cmd;
>
>      TPMBackend *be_driver;
> @@ -240,6 +243,13 @@ static void tpm_spapr_request_completed(TPMIf *ti, int 
> ret)
>
>      /* a max. of be_buffer_size bytes can be transported */
>      len = MIN(tpm_cmd_get_size(s->buffer), s->be_buffer_size);
> +
> +    if (runstate_check(RUN_STATE_FINISH_MIGRATE)) {
> +        /* defer delivery of response until .post_load */
> +        s->numbytes = len;
> +        return;
> +    }
> +
>      rc = spapr_vio_dma_write(&s->vdev, be32_to_cpu(crq->data),
>                               s->buffer, len);
>
> @@ -288,11 +298,13 @@ static void tpm_spapr_reset(SpaprVioDevice *dev)
>      SpaprTpmState *s = VIO_SPAPR_VTPM(dev);
>
>      s->state = SPAPR_VTPM_STATE_NONE;
> +    s->numbytes = 0;
>
>      s->be_tpm_version = tpm_backend_get_tpm_version(s->be_driver);
>
>      s->be_buffer_size = MIN(tpm_backend_get_buffer_size(s->be_driver),
>                              TPM_SPAPR_BUFFER_MAX);
> +    s->suspend_buffer = g_realloc(s->suspend_buffer, s->be_buffer_size);
>
>      tpm_backend_reset(s->be_driver);
>      tpm_spapr_do_startup_tpm(s, s->be_buffer_size);
> @@ -309,9 +321,62 @@ static enum TPMVersion tpm_spapr_get_version(TPMIf *ti)
>      return tpm_backend_get_tpm_version(s->be_driver);
>  }
>
> +/* persistent state handling */
> +
> +static int tpm_spapr_pre_save(void *opaque)
> +{
> +    SpaprTpmState *s = opaque;
> +
> +    tpm_backend_finish_sync(s->be_driver);
> +
> +    if (s->numbytes) {
> +        memcpy(s->suspend_buffer, s->buffer, s->numbytes);
> +    }
> +
> +    trace_tpm_spapr_pre_save(s->numbytes);
> +    /*
> +     * we cannot deliver the results to the VM since DMA would touch VM 
> memory
> +     */
> +
> +    return 0;
> +}
> +
> +static int tpm_spapr_post_load(void *opaque, int version_id)
> +{
> +    SpaprTpmState *s = opaque;
> +
> +    if (s->numbytes) {
> +        trace_tpm_spapr_post_load();
> +
> +        memcpy(s->buffer, s->suspend_buffer,
> +               MIN(s->numbytes, s->be_buffer_size));
> +        /* deliver the results to the VM via DMA */
> +        tpm_spapr_request_completed(TPM_IF(s), 0);
> +        s->numbytes = 0;
> +    }
> +
> +    return 0;
> +}
> +
>  static const VMStateDescription vmstate_spapr_vtpm = {
>      .name = "tpm-spapr",
> -    .unmigratable = 1,
> +    .version_id = 1,
> +    .minimum_version_id = 0,
> +    .minimum_version_id_old = 0,


Yyou should leave all the fields to 0 (there is no version 0 so far).
Thus no need to have them set explicitly either.

> +    .pre_save = tpm_spapr_pre_save,
> +    .post_load = tpm_spapr_post_load,
> +    .fields = (VMStateField[]) {
> +        VMSTATE_SPAPR_VIO(vdev, SpaprTpmState),
> +
> +        VMSTATE_UINT8(state, SpaprTpmState),
> +        VMSTATE_UINT32(numbytes, SpaprTpmState),
> +        VMSTATE_VBUFFER_ALLOC_UINT32(suspend_buffer,
> +                                     SpaprTpmState, 0, NULL,
> +                                     numbytes),
> +        /* remember DMA address */
> +        VMSTATE_UINT32(crq.data, SpaprTpmState),
> +        VMSTATE_END_OF_LIST(),
> +    }
>  };
>
>  static Property tpm_spapr_properties[] = {
> diff --git a/hw/tpm/trace-events b/hw/tpm/trace-events
> index 9143a8eaa3..5592cec7de 100644
> --- a/hw/tpm/trace-events
> +++ b/hw/tpm/trace-events
> @@ -67,3 +67,5 @@ tpm_spapr_do_crq_get_version(uint32_t version) "response: 
> version %u"
>  tpm_spapr_do_crq_prepare_to_suspend(void) "response: preparing to suspend"
>  tpm_spapr_do_crq_unknown_msg_type(uint8_t type) "Unknown message type 0x%02x"
>  tpm_spapr_do_crq_unknown_crq(uint8_t raw1, uint8_t raw2) "unknown CRQ 0x%02x 
> 0x%02x ..."
> +tpm_spapr_pre_save(uint32_t v) "Number of TPM response bytes to deliver 
> after resume: %u"
> +tpm_spapr_post_load(void) "Delivering TPM response after resume"
> --
> 2.24.1
>
>


-- 
Marc-André Lureau