Re: [PATCH] tpm/tpm_crb: Use start method value from ACPI table directly

[Jarkko Sakkinen]

On Fri, Aug 25, 2017 at 06:28:55PM -0500, Jiandi An wrote:
> This patch gets rid of dealing with intermediate flag for start method
> and use start method value from ACPI table directly.
> 
> For ARM64, the locality is handled by Trust Zone in FW.  The layout
> does not have crb_regs_head.  It is hitting the following line.
> dev_warn(dev, FW_BUG "Bad ACPI memory layout");
> 
> Current code excludes CRB_FL_ACPI_START for this check.  Now since
> ARM64 support for TPM CRB is added, CRB_FL_CRB_SMC_START should also be
> excluded from this check.
> 
> For goIdle and cmdReady where code was excluding CRB_FL_ACPI_START only
> (do nothing for ACPI start method), CRB_FL_CRB_SMC_START was also
> excluded as ARM64 SMC start method does not have TPM_CRB_CTRL_REQ.
> 
> However with special PPT workaround requiring CRB_FL_CRB_START to be
> set in addition to CRB_FL_ACPI_START and the addition flag of SMC
> start method CRB_FL_CRB_SMC_START, the code has become difficult to
> maintain and undrestand.  It is better to make code deal with start
> method value from ACPI table directly.
> 
> Signed-off-by: Jiandi An <anjiandi@xxxxxxxxxxxxxx>
> ---
>  drivers/char/tpm/tpm_crb.c | 59 +++++++++++++++++++++++-----------------------
>  1 file changed, 29 insertions(+), 30 deletions(-)
> 
> diff --git a/drivers/char/tpm/tpm_crb.c b/drivers/char/tpm/tpm_crb.c
> index 8f0a98d..7b3c2a8 100644
> --- a/drivers/char/tpm/tpm_crb.c
> +++ b/drivers/char/tpm/tpm_crb.c
> @@ -92,14 +92,9 @@ enum crb_status {
>  	CRB_DRV_STS_COMPLETE	= BIT(0),
>  };
>  
> -enum crb_flags {
> -	CRB_FL_ACPI_START	= BIT(0),
> -	CRB_FL_CRB_START	= BIT(1),
> -	CRB_FL_CRB_SMC_START	= BIT(2),
> -};
> -
>  struct crb_priv {
> -	unsigned int flags;
> +	u32 sm;
> +	const char *hid;
>  	void __iomem *iobase;
>  	struct crb_regs_head __iomem *regs_h;
>  	struct crb_regs_tail __iomem *regs_t;
> @@ -128,14 +123,16 @@ struct tpm2_crb_smc {
>   * Anyhow, we do not wait here as a consequent CMD_READY request
>   * will be handled correctly even if idle was not completed.
>   *
> - * The function does nothing for devices with ACPI-start method.
> + * The function does nothing for devices with ACPI-start method
> + * or SMC-start method.
>   *
>   * Return: 0 always
>   */
>  static int __maybe_unused crb_go_idle(struct device *dev, struct crb_priv *priv)
>  {
> -	if ((priv->flags & CRB_FL_ACPI_START) ||
> -	    (priv->flags & CRB_FL_CRB_SMC_START))
> +	if ((priv->sm == ACPI_TPM2_START_METHOD) ||
> +	    (priv->sm == ACPI_TPM2_COMMAND_BUFFER_WITH_START_METHOD) ||
> +	    (priv->sm == ACPI_TPM2_COMMAND_BUFFER_WITH_ARM_SMC))
>  		return 0;
>  
>  	iowrite32(CRB_CTRL_REQ_GO_IDLE, &priv->regs_t->ctrl_req);
> @@ -174,14 +171,16 @@ static bool crb_wait_for_reg_32(u32 __iomem *reg, u32 mask, u32 value,
>   * The device should respond within TIMEOUT_C.
>   *
>   * The function does nothing for devices with ACPI-start method
> + * or SMC-start method.
>   *
>   * Return: 0 on success -ETIME on timeout;
>   */
>  static int __maybe_unused crb_cmd_ready(struct device *dev,
>  					struct crb_priv *priv)
>  {
> -	if ((priv->flags & CRB_FL_ACPI_START) ||
> -	    (priv->flags & CRB_FL_CRB_SMC_START))
> +	if ((priv->sm == ACPI_TPM2_START_METHOD) ||
> +	    (priv->sm == ACPI_TPM2_COMMAND_BUFFER_WITH_START_METHOD) ||
> +	    (priv->sm == ACPI_TPM2_COMMAND_BUFFER_WITH_ARM_SMC))
>  		return 0;
>  
>  	iowrite32(CRB_CTRL_REQ_CMD_READY, &priv->regs_t->ctrl_req);
> @@ -325,13 +324,20 @@ static int crb_send(struct tpm_chip *chip, u8 *buf, size_t len)
>  	/* Make sure that cmd is populated before issuing start. */
>  	wmb();
>  
> -	if (priv->flags & CRB_FL_CRB_START)
> +	/* The reason for the extra quirk is that the PTT in 4th Gen Core CPUs
> +	 * report only ACPI start but in practice seems to require both
> +	 * CRB start, hence invoking CRB start method if hid == MSFT0101.
> +	 */
> +	if ((priv->sm == ACPI_TPM2_COMMAND_BUFFER) ||
> +	    (priv->sm == ACPI_TPM2_MEMORY_MAPPED) ||
> +	    (!strcmp(priv->hid, "MSFT0101")))
>  		iowrite32(CRB_START_INVOKE, &priv->regs_t->ctrl_start);
>  
> -	if (priv->flags & CRB_FL_ACPI_START)
> +	if ((priv->sm == ACPI_TPM2_START_METHOD) ||
> +	    (priv->sm == ACPI_TPM2_COMMAND_BUFFER_WITH_START_METHOD))
>  		rc = crb_do_acpi_start(chip);
>  
> -	if (priv->flags & CRB_FL_CRB_SMC_START) {
> +	if (priv->sm == ACPI_TPM2_COMMAND_BUFFER_WITH_ARM_SMC) {
>  		iowrite32(CRB_START_INVOKE, &priv->regs_t->ctrl_start);
>  		rc = tpm_crb_smc_start(&chip->dev, priv->smc_func_id);
>  	}
> @@ -345,7 +351,9 @@ static void crb_cancel(struct tpm_chip *chip)
>  
>  	iowrite32(CRB_CANCEL_INVOKE, &priv->regs_t->ctrl_cancel);
>  
> -	if ((priv->flags & CRB_FL_ACPI_START) && crb_do_acpi_start(chip))
> +	if (((priv->sm == ACPI_TPM2_START_METHOD) ||
> +	    (priv->sm == ACPI_TPM2_COMMAND_BUFFER_WITH_START_METHOD)) &&
> +	     crb_do_acpi_start(chip))
>  		dev_err(&chip->dev, "ACPI Start failed\n");
>  }
>  
> @@ -458,7 +466,8 @@ static int crb_map_io(struct acpi_device *device, struct crb_priv *priv,
>  	 * the control area, as one nice sane region except for some older
>  	 * stuff that puts the control area outside the ACPI IO region.
>  	 */
> -	if (!(priv->flags & CRB_FL_ACPI_START)) {
> +	if ((priv->sm == ACPI_TPM2_COMMAND_BUFFER) ||
> +	    (priv->sm == ACPI_TPM2_MEMORY_MAPPED)) {
>  		if (buf->control_address == io_res.start +
>  		    sizeof(*priv->regs_h))
>  			priv->regs_h = priv->iobase;
> @@ -552,18 +561,6 @@ static int crb_acpi_add(struct acpi_device *device)
>  	if (!priv)
>  		return -ENOMEM;
>  
> -	/* The reason for the extra quirk is that the PTT in 4th Gen Core CPUs
> -	 * report only ACPI start but in practice seems to require both
> -	 * ACPI start and CRB start.
> -	 */
> -	if (sm == ACPI_TPM2_COMMAND_BUFFER || sm == ACPI_TPM2_MEMORY_MAPPED ||
> -	    !strcmp(acpi_device_hid(device), "MSFT0101"))
> -		priv->flags |= CRB_FL_CRB_START;
> -
> -	if (sm == ACPI_TPM2_START_METHOD ||
> -	    sm == ACPI_TPM2_COMMAND_BUFFER_WITH_START_METHOD)
> -		priv->flags |= CRB_FL_ACPI_START;
> -
>  	if (sm == ACPI_TPM2_COMMAND_BUFFER_WITH_ARM_SMC) {
>  		if (buf->header.length < (sizeof(*buf) + sizeof(*crb_smc))) {
>  			dev_err(dev,
> @@ -574,9 +571,11 @@ static int crb_acpi_add(struct acpi_device *device)
>  		}
>  		crb_smc = ACPI_ADD_PTR(struct tpm2_crb_smc, buf, sizeof(*buf));
>  		priv->smc_func_id = crb_smc->smc_func_id;
> -		priv->flags |= CRB_FL_CRB_SMC_START;
>  	}
>  
> +	priv->sm = sm;
> +	priv->hid = acpi_device_hid(device);
> +
>  	rc = crb_map_io(device, priv, buf);
>  	if (rc)
>  		return rc;
> -- 
> Jiandi An
> Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc.
> Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.

Tested-by: Jarkko Sakkinen <jarkko.sakkine@xxxxxxxxxxxxxxx>

I run smoke test suite [1]:

$ python -m unittest -v tpm2_smoke
test_seal_with_auth (tpm2_smoke.SmokeTest) ... ok
test_seal_with_policy (tpm2_smoke.SmokeTest) ... ok
test_seal_with_too_long_auth (tpm2_smoke.SmokeTest) ... ok
test_unseal_with_wrong_auth (tpm2_smoke.SmokeTest) ... ok
test_unseal_with_wrong_policy (tpm2_smoke.SmokeTest) ... ok
test_flush_context (tpm2_smoke.SpaceTest) ... ok
test_get_handles (tpm2_smoke.SpaceTest) ... ok
test_make_two_spaces (tpm2_smoke.SpaceTest) ... ok

----------------------------------------------------------------------
Ran 8 tests in 25.816s

OK

This doesn't verify that things work on ARM64 because for that I do not
pose a test platform. However, since tpm_crb is not in wide use yet on
that platform I do not think it matters. And the code changes do not
have huge potential to cause collateral damage even if they were broken
on that platform.

[1] https://github.com/jsakkine-intel/tpm2-scripts

/Jarkko