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Message-ID: <20200625220023.GI20341@linux.intel.com>
Date: Fri, 26 Jun 2020 01:00:23 +0300
From: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To: amirmizi6@...il.com
Cc: Eyal.Cohen@...oton.com, oshrialkoby85@...il.com,
alexander.steffen@...ineon.com, robh+dt@...nel.org,
peterhuewe@....de, christophe-h.richard@...com, jgg@...pe.ca,
arnd@...db.de, gregkh@...uxfoundation.org,
devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-integrity@...r.kernel.org, oshri.alkoby@...oton.com,
tmaimon77@...il.com, gcwilson@...ibm.com, kgoldman@...ibm.com,
Dan.Morav@...oton.com, oren.tanami@...oton.com,
shmulik.hager@...oton.com, amir.mizinski@...oton.com,
Christophe Ricard <christophe-h.ricard@...com>
Subject: Re: [PATCH v12 3/9] tpm: tpm_tis: Add retry in case of protocol
failure.
On Thu, Jun 25, 2020 at 05:46:43PM +0300, amirmizi6@...il.com wrote:
> From: Amir Mizinski <amirmizi6@...il.com>
>
> Added a retry mechanism on any protocol error when sending a command or
> receiving a response. This was changed to comply with
> the TCG PC Client Device Driver Design Principles for TPM 2.0.
We don't have to comply with this.
> When sending a command, a loop is added in "tpm_tis_send_main()" that calls
> "tpm_tis_send_data()" and then issues a retry attempt if any error occurs.
> When receiving a response, the following new function derived from
> "tpm_tis_recv()" is added: "__tpm_tis_recv()". "tpm_tis_recv()" is modified
> to call "__tpm_tis_recv()" in a loop. If any error occurs, a retry is
> initiated by setting TPM_STS.responseRetry and "__tpm_tis_recv()" is
> called again.
> In both cases a retry is attempted up to "TPM_RETRY" times.
>
> Co-developed-by: Christophe Ricard <christophe-h.ricard@...com>
> Signed-off-by: Christophe Ricard <christophe-h.ricard@...com>
> Signed-off-by: Amir Mizinski <amirmizi6@...il.com>
> ---
> drivers/char/tpm/tpm_tis_core.c | 62 ++++++++++++++++++++++++++---------------
> drivers/char/tpm/tpm_tis_core.h | 1 +
> 2 files changed, 41 insertions(+), 22 deletions(-)
>
> diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
> index 6b33620..e136467 100644
> --- a/drivers/char/tpm/tpm_tis_core.c
> +++ b/drivers/char/tpm/tpm_tis_core.c
> @@ -305,29 +305,24 @@ static int recv_data(struct tpm_chip *chip, u8 *buf, size_t count)
> return size;
> }
>
> -static int tpm_tis_recv(struct tpm_chip *chip, u8 *buf, size_t count)
> +static int __tpm_tis_recv(struct tpm_chip *chip, u8 *buf, size_t count)
> {
> struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev);
> int size = 0;
> int status;
> u32 expected;
>
> - if (count < TPM_HEADER_SIZE) {
> - size = -EIO;
> - goto out;
> - }
> -
> size = recv_data(chip, buf, TPM_HEADER_SIZE);
> /* read first 10 bytes, including tag, paramsize, and result */
> if (size < TPM_HEADER_SIZE) {
> dev_err(&chip->dev, "Unable to read header\n");
> - goto out;
> + return size;
> }
>
> expected = be32_to_cpu(*(__be32 *) (buf + 2));
> if (expected > count || expected < TPM_HEADER_SIZE) {
> size = -EIO;
> - goto out;
> + return size;
> }
>
> size += recv_data(chip, &buf[TPM_HEADER_SIZE],
> @@ -335,22 +330,45 @@ static int tpm_tis_recv(struct tpm_chip *chip, u8 *buf, size_t count)
> if (size < expected) {
> dev_err(&chip->dev, "Unable to read remainder of result\n");
> size = -ETIME;
> - goto out;
> + return size;
> }
>
> if (tpm_tis_wait_for_stat(chip, TPM_STS_VALID, TPM_STS_VALID,
> chip->timeout_c, &priv->int_queue,
> false) < 0) {
> size = -ETIME;
> - goto out;
> + return size;
> }
> +
> status = tpm_tis_status(chip);
> if (status & TPM_STS_DATA_AVAIL) { /* retry? */
> dev_err(&chip->dev, "Error left over data\n");
> size = -EIO;
> + return size;
> + }
> +
> + return size;
> +}
> +
> +static int tpm_tis_recv(struct tpm_chip *chip, u8 *buf, size_t count)
> +{
> + struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev);
> + int size;
> + int i;
> +
> + if (count < TPM_HEADER_SIZE) {
> + size = -EIO;
> goto out;
> }
>
> + for (i = 0; i < TPM_RETRY; i++) {
> + size = __tpm_tis_recv(chip, buf, count);
> + if (size <= 0)
> + tpm_tis_write8(priv, TPM_STS(priv->locality),
> + TPM_STS_RESPONSE_RETRY);
> + else
> + goto out;
> + }
> out:
> tpm_tis_ready(chip);
> return size;
> @@ -375,7 +393,7 @@ static int tpm_tis_send_data(struct tpm_chip *chip, const u8 *buf, size_t len)
> chip->timeout_b, &priv->int_queue,
> false) < 0) {
> rc = -ETIME;
> - goto out_err;
> + return rc;
> }
> }
>
> @@ -384,13 +402,13 @@ static int tpm_tis_send_data(struct tpm_chip *chip, const u8 *buf, size_t len)
> if (burstcnt < 0) {
> dev_err(&chip->dev, "Unable to read burstcount\n");
> rc = burstcnt;
> - goto out_err;
> + return rc;
> }
> burstcnt = min_t(int, burstcnt, len - count);
> rc = tpm_tis_write_bytes(priv, TPM_DATA_FIFO(priv->locality),
> burstcnt, buf + count);
> if (rc < 0)
> - goto out_err;
> + return rc;
>
> count += burstcnt;
> }
> @@ -398,14 +416,10 @@ static int tpm_tis_send_data(struct tpm_chip *chip, const u8 *buf, size_t len)
> TPM_STS_VALID, chip->timeout_a,
> &priv->int_queue, false) < 0) {
> rc = -ETIME;
> - goto out_err;
> + return rc;
> }
>
> return 0;
> -
> -out_err:
> - tpm_tis_ready(chip);
> - return rc;
> }
>
> static void disable_interrupts(struct tpm_chip *chip)
> @@ -434,13 +448,17 @@ static void disable_interrupts(struct tpm_chip *chip)
> static int tpm_tis_send_main(struct tpm_chip *chip, const u8 *buf, size_t len)
> {
> struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev);
> - int rc;
> + int rc, i;
> u32 ordinal;
> unsigned long dur;
>
> - rc = tpm_tis_send_data(chip, buf, len);
> - if (rc < 0)
> - return rc;
> + for (i = 0; i < TPM_RETRY; i++) {
> + rc = tpm_tis_send_data(chip, buf, len);
> + if (rc >= 0)
> + break;
> + }
> + if (i == TPM_RETRY)
> + goto out_err;
>
> /* go and do it */
> rc = tpm_tis_write8(priv, TPM_STS(priv->locality), TPM_STS_GO);
> diff --git a/drivers/char/tpm/tpm_tis_core.h b/drivers/char/tpm/tpm_tis_core.h
> index d06c65b..6cc6b76 100644
> --- a/drivers/char/tpm/tpm_tis_core.h
> +++ b/drivers/char/tpm/tpm_tis_core.h
> @@ -34,6 +34,7 @@ enum tis_status {
> TPM_STS_GO = 0x20,
> TPM_STS_DATA_AVAIL = 0x10,
> TPM_STS_DATA_EXPECT = 0x08,
> + TPM_STS_RESPONSE_RETRY = 0x02,
> };
>
> enum tis_int_flags {
> --
> 2.7.4
>
Just based on the explanation this looks like a bunch of unconsidered
changes. You have explain yourself better.
/Jarkko
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