Re: [PATCH v11 2/8] tpm: tpm_tis: Fix expected bit handling and send all bytes in one shot without last byte in exception

From: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
To: amirmizi6@gmail.com
Cc: Eyal.Cohen@nuvoton.com, oshrialkoby85@gmail.com,
	alexander.steffen@infineon.com, robh+dt@kernel.org,
	peterhuewe@gmx.de, christophe-h.richard@st.com, jgg@ziepe.ca,
	arnd@arndb.de, gregkh@linuxfoundation.org,
	devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-integrity@vger.kernel.org, oshri.alkoby@nuvoton.com,
	tmaimon77@gmail.com, gcwilson@us.ibm.com, kgoldman@us.ibm.com,
	Dan.Morav@nuvoton.com, oren.tanami@nuvoton.com,
	shmulik.hager@nuvoton.com, amir.mizinski@nuvoton.com,
	Benoit Houyere <benoit.houyere@st.com>
Subject: Re: [PATCH v11 2/8] tpm: tpm_tis: Fix expected bit handling and send all bytes in one shot without last byte in exception
Date: Tue, 23 Jun 2020 00:54:53 +0300	[thread overview]
Message-ID: <20200622215453.GD22727@linux.intel.com> (raw)
In-Reply-To: <20200618134344.243537-3-amirmizi6@gmail.com>

On Thu, Jun 18, 2020 at 04:43:37PM +0300, amirmizi6@gmail.com wrote:
> From: Amir Mizinski <amirmizi6@gmail.com>
> 
> Detected the following incorrect implementation of the send command:
> polling on the TPM_STS.stsValid field followed by checking the
> TPM_STS.expect field only once. Since TPM_STS.stsValid represents the
> TPM_STS.expect validity, both fields should be polled at the same time.
> 
> This fix modifies the signature of wait_for_tpm_stat(), adding an
> additional "mask_result" parameter to its call. wait_for_tpm_stat() is now
> polling the TPM_STS with a mask and waits for the value in mask_result.
> The fix adds the ability to check if certain TPM_STS bits have been
> cleared.
> 
> This change is also aligned to verifying the CRC on I2C TPM. The CRC
> verification should be done after the TPM_STS.expect field is cleared
> (TPM received all expected command bytes and set the calculated CRC value
> in the register).
> 
> In addition, the send command was changed to comply with
> TCG_DesignPrinciples_TPM2p0Driver_vp24_pubrev.pdf as follows:
> - send all command bytes in one loop
> - remove special handling of the last byte
> 
> Suggested-by: Benoit Houyere <benoit.houyere@st.com>
> Signed-off-by: Amir Mizinski <amirmizi6@gmail.com>

Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>

If this patch set needs a further update, you could rename the function
as 'tpm_tis_wait_for_stat()' (can be part of this patch). It's better
aligned with other naming and gives better picture of the scope of this
function.

/Jarkko