| Message ID | 20171004102924.12355-3-nayna@linux.vnet.ibm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Wed, Oct 04, 2017 at 06:29:21AM -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. Further, > some TPMs have a static burstcount, when the value remains zero > until the entire FIFO is empty. > > 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 states. The performance of a > 34 byte extend on a TPM 1.2 with an 8 byte burstcount improved from > 41msec to 14msec. > > 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 <kgold@linux.vnet.ibm.com> in > conjunction with the TPM Device Driver work group. > Signed-off-by: Nayna Jain <nayna@linux.vnet.ibm.com> > Acked-by: Mimi Zohar <zohar@linux.vnet.ibm.com> > --- > drivers/char/tpm/tpm_tis_core.c | 42 ++++++++++++++++------------------------- > 1 file changed, 16 insertions(+), 26 deletions(-) > > diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c > index b33126a35694..8da425e1783f 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 +329,26 @@ 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; > + /* > + * 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; > + } > > - count += burstcnt; > + burstcnt = len - 1; > > - 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; > - } > - } > + rc = tpm_tis_write_bytes(priv, TPM_DATA_FIFO(priv->locality), > + burstcnt, buf); Otherwise, this looks good but I don't understand why you assign 'len - 1' to 'brustcnt' and pass it to tpm_tis_write_bytes() instead of just passing 'len - 1'. I mean no relation to burst count, right? /Jarkko -- To unsubscribe from this list: send the line "unsubscribe linux-security-module" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 10/10/2017 08:34 PM, Jarkko Sakkinen wrote: > On Wed, Oct 04, 2017 at 06:29:21AM -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. Further, >> some TPMs have a static burstcount, when the value remains zero >> until the entire FIFO is empty. >> >> 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 states. The performance of a >> 34 byte extend on a TPM 1.2 with an 8 byte burstcount improved from >> 41msec to 14msec. >> >> 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 <kgold@linux.vnet.ibm.com> in >> conjunction with the TPM Device Driver work group. >> Signed-off-by: Nayna Jain <nayna@linux.vnet.ibm.com> >> Acked-by: Mimi Zohar <zohar@linux.vnet.ibm.com> >> --- >> drivers/char/tpm/tpm_tis_core.c | 42 ++++++++++++++++------------------------- >> 1 file changed, 16 insertions(+), 26 deletions(-) >> >> diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c >> index b33126a35694..8da425e1783f 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 +329,26 @@ 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; >> + /* >> + * 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; >> + } >> >> - count += burstcnt; >> + burstcnt = len - 1; >> >> - 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; >> - } >> - } >> + rc = tpm_tis_write_bytes(priv, TPM_DATA_FIFO(priv->locality), >> + burstcnt, buf); > Otherwise, this looks good but I don't understand why you assign 'len - > 1' to 'brustcnt' and pass it to tpm_tis_write_bytes() instead of just > passing 'len - 1'. I mean no relation to burst count, right? Yeah, I can just send 'len - 1'. Will do this change. Thanks & Regards, - Nayna > > /Jarkko > -- To unsubscribe from this list: send the line "unsubscribe linux-security-module" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c index b33126a35694..8da425e1783f 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 +329,26 @@ 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; + /* + * 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; + } - count += burstcnt; + burstcnt = len - 1; - 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; - } - } + rc = tpm_tis_write_bytes(priv, TPM_DATA_FIFO(priv->locality), + burstcnt, 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;