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

[msuchanek <msuchanek@suse.de>]

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On Fri, 24 Feb 2017 20:35:16 +0100
Michal Suchanek <msuchanek@suse.de> wrote:

> The crq is passed in registers and is the same on BE and LE hosts.
> 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@suse.de>
> Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
> ---
> v2
> 
> fix typos and spelling in comments
> ---
>  drivers/char/tpm/tpm_ibmvtpm.c | 96
> ++++++++++++++++++++++++++---------------- 1 file changed, 60
> insertions(+), 36 deletions(-)
> 
> diff --git a/drivers/char/tpm/tpm_ibmvtpm.c
> b/drivers/char/tpm/tpm_ibmvtpm.c index 1b9d61ffe991..89027339d55f
> 100644 --- a/drivers/char/tpm/tpm_ibmvtpm.c
> +++ b/drivers/char/tpm/tpm_ibmvtpm.c
> @@ -39,19 +39,63 @@ 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 tpm crq (second
> word is reserved)
> + *
> + * Return:
> + *	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
> + * @valid:	Valid field
> + * @msg:	Type field
> + * @len:	Length field
> + * @data:	Data field
> + *
> + * 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 register avoiding byteswap altogether. Endian
> only affects
> + * memory loads and stores - registers are internally represented
> the same. *
>   * Return:
> - *	0 -Sucess
> + *	0 (H_SUCCESS) - Success
>   *	Non-zero - Failure
>   */
> -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);
>  }
>  
>  /**
> @@ -109,8 +153,6 @@ 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) {
> @@ -137,10 +179,6 @@ 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 @@ -148,8 +186,9 @@ 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;
> @@ -182,15 +221,10 @@ 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); @@ -210,15 +244,10 @@ 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); @@ -238,7 +267,7 @@ 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); @@ -258,7 +287,7 @@ 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);
> @@ -336,15 +365,10 @@ 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);