在 2022/7/7 0:41, Jason Andryuk 写道:
> WEC TPMs (in 1.2 mode) and NTC (in 2.0 mode) have been observer to
> frequently, but intermittently, fail probe with:
> tpm_tis: probe of 00:09 failed with error -1
>
> Added debugging output showed that the request_locality in
> tpm_tis_core_init succeeds, but then the tpm_chip_start fails when its
> call to tpm_request_locality -> request_locality fails.
>
> The access register in check_locality would show:
> 0x80 TPM_ACCESS_VALID
> 0x82 TPM_ACCESS_VALID | TPM_ACCESS_REQUEST_USE
> 0x80 TPM_ACCESS_VALID
> continuing until it times out. TPM_ACCESS_ACTIVE_LOCALITY (0x20) doesn't
> get set which would end the wait.
>
> My best guess is something racy was going on between release_locality's
> write and request_locality's write. There is no wait in
> release_locality to ensure that the locality is released, so the
> subsequent request_locality could confuse the TPM?
>
> tpm_chip_start grabs locality 0, and updates chip->locality. Call that
> before the TPM_INT_ENABLE write, and drop the explicit request/release
> calls. tpm_chip_stop performs the release. With this, we switch to
> using chip->locality instead of priv->locality. The probe failure is
> not seen after this.
>
> commit 0ef333f5ba7f ("tpm: add request_locality before write
> TPM_INT_ENABLE") added a request_locality/release_locality pair around
> tpm_tis_write32 TPM_INT_ENABLE, but there is a read of
> TPM_INT_ENABLE for the intmask which should also have the locality
> grabbed. tpm_chip_start is moved before that to have the locality open
> during the read.
>
> Fixes: 0ef333f5ba7f ("tpm: add request_locality before write TPM_INT_ENABLE")
0ef333f5ba7f is probably not the commit that introduced the problem? As
you said the problem was in 5.4 and the commit was merged in 5.16.
> CC: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Jason Andryuk <jandryuk@xxxxxxxxx>
> ---
> The probe failure was seen on 5.4, 5.15 and 5.17.
>
> commit e42acf104d6e ("tpm_tis: Clean up locality release") removed the
> release wait. I haven't tried, but re-introducing that would probably
> fix this issue. It's hard to know apriori when a synchronous wait is
> needed, and they don't seem to be needed typically. Re-introducing the
> wait would re-introduce a wait in all cases.
>
> Surrounding the read of TPM_INT_ENABLE with grabbing the locality may
> not be necessary? It looks like the code only grabs a locality for
> writing, but that asymmetry is surprising to me.
>
> tpm_chip and tpm_tis_data track the locality separately. Should the
> tpm_tis_data one be removed so they don't get out of sync?
> ---
> drivers/char/tpm/tpm_tis_core.c | 20 ++++++++------------
> 1 file changed, 8 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
> index dc56b976d816..529c241800c0 100644
> --- a/drivers/char/tpm/tpm_tis_core.c
> +++ b/drivers/char/tpm/tpm_tis_core.c
> @@ -986,8 +986,13 @@ int tpm_tis_core_init(struct device *dev, struct tpm_tis_data *priv, int irq,
> goto out_err;
> }
>
> + /* Grabs locality 0. */
> + rc = tpm_chip_start(chip);
> + if (rc)
> + goto out_err;
> +
> /* Take control of the TPM's interrupt hardware and shut it off */
> - rc = tpm_tis_read32(priv, TPM_INT_ENABLE(priv->locality), &intmask);
> + rc = tpm_tis_read32(priv, TPM_INT_ENABLE(chip->locality), &intmask);
> if (rc < 0)
> goto out_err;
>
> @@ -995,19 +1000,10 @@ int tpm_tis_core_init(struct device *dev, struct tpm_tis_data *priv, int irq,
> TPM_INTF_DATA_AVAIL_INT | TPM_INTF_STS_VALID_INT;
> intmask &= ~TPM_GLOBAL_INT_ENABLE;
>
> - rc = request_locality(chip, 0);
> - if (rc < 0) {
> - rc = -ENODEV;
> - goto out_err;
> - }
> -
> - tpm_tis_write32(priv, TPM_INT_ENABLE(priv->locality), intmask);
> - release_locality(chip, 0);
> + tpm_tis_write32(priv, TPM_INT_ENABLE(chip->locality), intmask);
>
> - rc = tpm_chip_start(chip);
> - if (rc)
> - goto out_err;
> rc = tpm2_probe(chip);
> + /* Releases locality 0. */
> tpm_chip_stop(chip);
> if (rc)
> goto out_err;
>
--
Regards
Chen Jun
