From mboxrd@z Thu Jan 1 00:00:00 1970 From: jarkko.sakkinen@linux.intel.com (Jarkko Sakkinen) Date: Thu, 19 Oct 2017 17:23:12 +0300 Subject: [PATCH v4 2/4] tpm: ignore burstcount to improve tpm_tis send() performance In-Reply-To: <20171017203232.2262-3-nayna@linux.vnet.ibm.com> References: <20171017203232.2262-1-nayna@linux.vnet.ibm.com> <20171017203232.2262-3-nayna@linux.vnet.ibm.com> Message-ID: <20171019142312.tq4upw4paqom3jo5@linux.intel.com> To: linux-security-module@vger.kernel.org List-Id: linux-security-module.vger.kernel.org On Tue, Oct 17, 2017 at 04:32:30PM -0400, Nayna Jain wrote: > The TPM burstcount status indicates the number of bytes that can > be sent to the TPM without causing bus wait states. Effectively, > it is the number of empty bytes in the command FIFO. > > This patch optimizes the tpm_tis_send_data() function by checking > the burstcount only once. And if the burstcount is valid, it writes > all the bytes at once, permitting wait state. > > After this change, performance on a TPM 1.2 with an 8 byte > burstcount for 1000 extends improved from ~41sec to ~14sec. > > Suggested-by: Ken Goldman in > conjunction with the TPM Device Driver work group. > Signed-off-by: Nayna Jain > Acked-by: Mimi Zohar > --- > drivers/char/tpm/tpm_tis_core.c | 42 +++++++++++++++-------------------------- > 1 file changed, 15 insertions(+), 27 deletions(-) > > diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c > index b33126a35694..993328ae988c 100644 > --- a/drivers/char/tpm/tpm_tis_core.c > +++ b/drivers/char/tpm/tpm_tis_core.c > @@ -316,7 +316,6 @@ static int tpm_tis_send_data(struct tpm_chip *chip, u8 *buf, size_t len) > { > struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev); > int rc, status, burstcnt; > - size_t count = 0; > bool itpm = priv->flags & TPM_TIS_ITPM_WORKAROUND; > > status = tpm_tis_status(chip); > @@ -330,35 +329,24 @@ static int tpm_tis_send_data(struct tpm_chip *chip, u8 *buf, size_t len) > } > } > > - while (count < len - 1) { > - burstcnt = get_burstcount(chip); > - if (burstcnt < 0) { > - dev_err(&chip->dev, "Unable to read burstcount\n"); > - rc = burstcnt; > - goto out_err; > - } > - burstcnt = min_t(int, burstcnt, len - count - 1); > - rc = tpm_tis_write_bytes(priv, TPM_DATA_FIFO(priv->locality), > - burstcnt, buf + count); > - if (rc < 0) > - goto out_err; > - > - count += burstcnt; > - > - if (wait_for_tpm_stat(chip, TPM_STS_VALID, chip->timeout_c, > - &priv->int_queue, false) < 0) { > - rc = -ETIME; > - goto out_err; > - } > - status = tpm_tis_status(chip); > - if (!itpm && (status & TPM_STS_DATA_EXPECT) == 0) { > - rc = -EIO; > - goto out_err; > - } > + /* > + * Get the initial burstcount to ensure TPM is ready to > + * accept data. > + */ > + burstcnt = get_burstcount(chip); > + if (burstcnt < 0) { > + dev_err(&chip->dev, "Unable to read burstcount\n"); > + rc = burstcnt; > + goto out_err; > } > > + rc = tpm_tis_write_bytes(priv, TPM_DATA_FIFO(priv->locality), > + len - 1, buf); > + if (rc < 0) > + goto out_err; > + > /* write last byte */ > - rc = tpm_tis_write8(priv, TPM_DATA_FIFO(priv->locality), buf[count]); > + rc = tpm_tis_write8(priv, TPM_DATA_FIFO(priv->locality), buf[len-1]); > if (rc < 0) > goto out_err; > > -- > 2.13.3 > Tested-by: Jarkko Sakkinen /Jarkko -- To unsubscribe from this list: send the line "unsubscribe linux-security-module" in the body of a message to majordomo at vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html