Re: [PATCH] tpm: ibmvtpm: simplify crq initialization and document crq format

[Jarkko Sakkinen]

On Tue, Jan 31, 2017 at 03:17:34PM +0100, Michal Suchanek wrote:
> 
> The crq is passed in registers so is the same on BE and LE hosts.

's/ so// ' ?

> However, current implementation allocates a structure on-stack to
> represent the crq, initializes the members swapping them to BE, and
> loads the structure swapping it from BE. This is pointless and causes
> GCC warnings about ununitialized members. Get rid of the structure and
> the warnings.
> 
> Signed-off-by: Michal Suchanek <msuchanek@xxxxxxx>
> ---
>  drivers/char/tpm/tpm_ibmvtpm.c | 92 +++++++++++++++++++++++++-----------------
>  1 file changed, 56 insertions(+), 36 deletions(-)
> 
> diff --git a/drivers/char/tpm/tpm_ibmvtpm.c b/drivers/char/tpm/tpm_ibmvtpm.c
> index 946025a7413b..b6402b1b76fe 100644
> --- a/drivers/char/tpm/tpm_ibmvtpm.c
> +++ b/drivers/char/tpm/tpm_ibmvtpm.c
> @@ -39,18 +39,58 @@ static struct vio_device_id tpm_ibmvtpm_device_table[] = {
>  MODULE_DEVICE_TABLE(vio, tpm_ibmvtpm_device_table);
>  
>  /**
> + *
> + * ibmvtpm_send_crq_word - Send a CRQ request
> + * @vdev:	vio device struct
> + * @w1:		pre-constructed first word of tmp crq (second word is reserved)
> + *
> + * Return value:
> + *	0 - Success
> + *	Non-zero - Failure
> + */
> +static int ibmvtpm_send_crq_word(struct vio_dev *vdev, u64 w1)
> +{
> +	return plpar_hcall_norets(H_SEND_CRQ, vdev->unit_address, w1, 0);
> +}
> +
> +/**
> + *
>   * ibmvtpm_send_crq - Send a CRQ request
>   * @vdev:	vio device struct
> - * @w1:		first word
> - * @w2:		second word
> + *
> + * The ibmvtpm crq is defined as follows:
> + *
> + * Byte  |   0   |   1   |   2   |   3   |   4   |   5   |   6   |   7
> + * -----------------------------------------------------------------------
> + * Word0 | Valid | Type  |     Length    |              Data
> + * -----------------------------------------------------------------------
> + * Word1 |                Reserved
> + * -----------------------------------------------------------------------
> + *
> + * Which matches the following structure (on bigendian host):
> + *
> + * struct ibmvtpm_crq {
> + *         u8 valid;
> + *         u8 msg;
> + *         __be16 len;
> + *         __be32 data;
> + *         __be64 reserved;
> + * } __attribute__((packed, aligned(8)));
> + *
> + * However, the value is passed in a register so just compute the numeric value
> + * to load into the registar avoiding byteswap altogether. Endian only affects
> + * memory loads and stores - registers are internally represented the same.
>   *
>   * Return value:
> - *	0 -Sucess
> + *	0 (H_SUCCESS) - Success
>   *	Non-zero - Failure

hould be "Return:" [1]

[1] http://lxr.free-electrons.com/source/Documentation/kernel-doc-nano-HOWTO.txt

>   */
> -static int ibmvtpm_send_crq(struct vio_dev *vdev, u64 w1, u64 w2)
> +static int ibmvtpm_send_crq(struct vio_dev *vdev,
> +		u8 valid, u8 msg, u16 len, u32 data)
>  {
> -	return plpar_hcall_norets(H_SEND_CRQ, vdev->unit_address, w1, w2);
> +	u64 w1 = ((u64)valid << 56) | ((u64)msg << 48) | ((u64)len << 32) |
> +		(u64)data;
> +	return ibmvtpm_send_crq_word(vdev, w1);
>  }
>  
>  /**
> @@ -106,8 +146,6 @@ static int tpm_ibmvtpm_recv(struct tpm_chip *chip, u8 *buf, size_t count)
>  static int tpm_ibmvtpm_send(struct tpm_chip *chip, u8 *buf, size_t count)
>  {
>  	struct ibmvtpm_dev *ibmvtpm = dev_get_drvdata(&chip->dev);
> -	struct ibmvtpm_crq crq;
> -	__be64 *word = (__be64 *)&crq;
>  	int rc, sig;
>  
>  	if (!ibmvtpm->rtce_buf) {
> @@ -134,10 +172,6 @@ static int tpm_ibmvtpm_send(struct tpm_chip *chip, u8 *buf, size_t count)
>  	spin_lock(&ibmvtpm->rtce_lock);
>  	ibmvtpm->res_len = 0;
>  	memcpy((void *)ibmvtpm->rtce_buf, (void *)buf, count);
> -	crq.valid = (u8)IBMVTPM_VALID_CMD;
> -	crq.msg = (u8)VTPM_TPM_COMMAND;
> -	crq.len = cpu_to_be16(count);
> -	crq.data = cpu_to_be32(ibmvtpm->rtce_dma_handle);
>  
>  	/*
>  	 * set the processing flag before the Hcall, since we may get the
> @@ -145,8 +179,9 @@ static int tpm_ibmvtpm_send(struct tpm_chip *chip, u8 *buf, size_t count)
>  	 */
>  	ibmvtpm->tpm_processing_cmd = true;
>  
> -	rc = ibmvtpm_send_crq(ibmvtpm->vdev, be64_to_cpu(word[0]),
> -			      be64_to_cpu(word[1]));
> +	rc = ibmvtpm_send_crq(ibmvtpm->vdev,
> +			IBMVTPM_VALID_CMD, VTPM_TPM_COMMAND,
> +			count, ibmvtpm->rtce_dma_handle);
>  	if (rc != H_SUCCESS) {
>  		dev_err(ibmvtpm->dev, "tpm_ibmvtpm_send failed rc=%d\n", rc);
>  		rc = 0;
> @@ -178,15 +213,10 @@ static u8 tpm_ibmvtpm_status(struct tpm_chip *chip)
>   */
>  static int ibmvtpm_crq_get_rtce_size(struct ibmvtpm_dev *ibmvtpm)
>  {
> -	struct ibmvtpm_crq crq;
> -	u64 *buf = (u64 *) &crq;
>  	int rc;
>  
> -	crq.valid = (u8)IBMVTPM_VALID_CMD;
> -	crq.msg = (u8)VTPM_GET_RTCE_BUFFER_SIZE;
> -
> -	rc = ibmvtpm_send_crq(ibmvtpm->vdev, cpu_to_be64(buf[0]),
> -			      cpu_to_be64(buf[1]));
> +	rc = ibmvtpm_send_crq(ibmvtpm->vdev,
> +			IBMVTPM_VALID_CMD, VTPM_GET_RTCE_BUFFER_SIZE, 0, 0);
>  	if (rc != H_SUCCESS)
>  		dev_err(ibmvtpm->dev,
>  			"ibmvtpm_crq_get_rtce_size failed rc=%d\n", rc);
> @@ -205,15 +235,10 @@ static int ibmvtpm_crq_get_rtce_size(struct ibmvtpm_dev *ibmvtpm)
>   */
>  static int ibmvtpm_crq_get_version(struct ibmvtpm_dev *ibmvtpm)
>  {
> -	struct ibmvtpm_crq crq;
> -	u64 *buf = (u64 *) &crq;
>  	int rc;
>  
> -	crq.valid = (u8)IBMVTPM_VALID_CMD;
> -	crq.msg = (u8)VTPM_GET_VERSION;
> -
> -	rc = ibmvtpm_send_crq(ibmvtpm->vdev, cpu_to_be64(buf[0]),
> -			      cpu_to_be64(buf[1]));
> +	rc = ibmvtpm_send_crq(ibmvtpm->vdev,
> +			IBMVTPM_VALID_CMD, VTPM_GET_VERSION, 0, 0);
>  	if (rc != H_SUCCESS)
>  		dev_err(ibmvtpm->dev,
>  			"ibmvtpm_crq_get_version failed rc=%d\n", rc);
> @@ -233,7 +258,7 @@ static int ibmvtpm_crq_send_init_complete(struct ibmvtpm_dev *ibmvtpm)
>  {
>  	int rc;
>  
> -	rc = ibmvtpm_send_crq(ibmvtpm->vdev, INIT_CRQ_COMP_CMD, 0);
> +	rc = ibmvtpm_send_crq_word(ibmvtpm->vdev, INIT_CRQ_COMP_CMD);
>  	if (rc != H_SUCCESS)
>  		dev_err(ibmvtpm->dev,
>  			"ibmvtpm_crq_send_init_complete failed rc=%d\n", rc);
> @@ -253,7 +278,7 @@ static int ibmvtpm_crq_send_init(struct ibmvtpm_dev *ibmvtpm)
>  {
>  	int rc;
>  
> -	rc = ibmvtpm_send_crq(ibmvtpm->vdev, INIT_CRQ_CMD, 0);
> +	rc = ibmvtpm_send_crq_word(ibmvtpm->vdev, INIT_CRQ_CMD);
>  	if (rc != H_SUCCESS)
>  		dev_err(ibmvtpm->dev,
>  			"ibmvtpm_crq_send_init failed rc=%d\n", rc);
> @@ -332,15 +357,10 @@ static int tpm_ibmvtpm_suspend(struct device *dev)
>  {
>  	struct tpm_chip *chip = dev_get_drvdata(dev);
>  	struct ibmvtpm_dev *ibmvtpm = dev_get_drvdata(&chip->dev);
> -	struct ibmvtpm_crq crq;
> -	u64 *buf = (u64 *) &crq;
>  	int rc = 0;
>  
> -	crq.valid = (u8)IBMVTPM_VALID_CMD;
> -	crq.msg = (u8)VTPM_PREPARE_TO_SUSPEND;
> -
> -	rc = ibmvtpm_send_crq(ibmvtpm->vdev, cpu_to_be64(buf[0]),
> -			      cpu_to_be64(buf[1]));
> +	rc = ibmvtpm_send_crq(ibmvtpm->vdev,
> +			IBMVTPM_VALID_CMD, VTPM_PREPARE_TO_SUSPEND, 0, 0);
>  	if (rc != H_SUCCESS)
>  		dev_err(ibmvtpm->dev,
>  			"tpm_ibmvtpm_suspend failed rc=%d\n", rc);
> -- 
> 2.10.2
> 

Otherwise, I do not see any issues but can somebody test this?  I cannot
and I rather not merge it before it is peer tested.

Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx>

/Jarkko