linux-kernel - Re: [PATCH v1 3/5] char: tpm: rewrite "tpm_tis_req

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Date:   Sun, 10 Nov 2019 11:00:10 -0700
From:   Jerry Snitselaar <jsnitsel@...hat.com>
To:     amirmizi6@...il.comg, Stefan Berger <stefanb@...ux.vnet.ibm.com>
Cc:     Eyal.Cohen@...oton.com, jarkko.sakkinen@...ux.intel.com,
        oshrialkoby85@...il.com, alexander.steffen@...ineon.com,
        robh+dt@...nel.org, mark.rutland@....com, peterhuewe@....de,
        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,
        ayna@...ux.vnet.ibm.com, Dan.Morav@...oton.com,
        oren.tanami@...oton.com, shmulik.hagar@...oton.com,
        amir.mizinski@...oton.com
Subject: Re: [PATCH v1 3/5] char: tpm: rewrite "tpm_tis_req_canceled()"

On Sun Nov 10 19, amirmizi6@...il.com wrote:
>From: Amir Mizinski <amirmizi6@...il.com>
>
>using this function while read/write data resulted in aborted operation.
>after investigating according to TCG TPM Profile (PTP) Specifications,
>i found cancel should happen only if TPM_STS.commandReady bit is lit
>and couldn't find a case when the current condition is valid.
>also only cmdReady bit need to be compared instead of the full lower status register byte.
>
>Signed-off-by: Amir Mizinski <amirmizi6@...il.com>
>---
> drivers/char/tpm/tpm_tis_core.c | 12 +-----------
> 1 file changed, 1 insertion(+), 11 deletions(-)
>
>diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
>index ce7f8a1..9016f06 100644
>--- a/drivers/char/tpm/tpm_tis_core.c
>+++ b/drivers/char/tpm/tpm_tis_core.c
>@@ -627,17 +627,7 @@ static int probe_itpm(struct tpm_chip *chip)
>
> static bool tpm_tis_req_canceled(struct tpm_chip *chip, u8 status)
> {
>-	struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev);
>-
>-	switch (priv->manufacturer_id) {
>-	case TPM_VID_WINBOND:
>-		return ((status == TPM_STS_VALID) ||
>-			(status == (TPM_STS_VALID | TPM_STS_COMMAND_READY)));
>-	case TPM_VID_STM:
>-		return (status == (TPM_STS_VALID | TPM_STS_COMMAND_READY));

Stefan were these cases you found that were deviating from the spec? Wondering
if dropping these will cause issues for these devices.

>-	default:
>-		return (status == TPM_STS_COMMAND_READY);
>-	}
>+	return ((status & TPM_STS_COMMAND_READY) == TPM_STS_COMMAND_READY);
> }
>
> static irqreturn_t tis_int_handler(int dummy, void *dev_id)
>-- 
>2.7.4
>