Re: [PATCH V2 1/1] PCI/DOE: Fix maximum data object length miscalculation

[Jonathan Cameron <Jonathan.Cameron@Huawei.com>]

On Wed, 16 Nov 2022 09:56:37 +0800
Li Ming <ming4.li@intel.com> wrote:

> The value of data object length 0x0 indicates 2^18 dwords being
> transferred. This patch adjusts the value of data object length for the
> above case on both sending side and receiving side.
> 
> Besides, it is unnecessary to check whether length is greater than
> SZ_1M while receiving a response data object, because length from LENGTH
> field of data object header, max value is 2^18.
> 
> Signed-off-by: Li Ming <ming4.li@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Thanks,


> ---
> v1->v2:
>  * Fix the value of PCI_DOE_MAX_LENGTH
>  * Moving length checking closer to transferring process
>  * Add a missing bracket
>  * Adjust patch description
> ---
>  drivers/pci/doe.c | 20 ++++++++++++++++----
>  1 file changed, 16 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/pci/doe.c b/drivers/pci/doe.c
> index e402f05068a5..66d9ab288646 100644
> --- a/drivers/pci/doe.c
> +++ b/drivers/pci/doe.c
> @@ -29,6 +29,9 @@
>  #define PCI_DOE_FLAG_CANCEL	0
>  #define PCI_DOE_FLAG_DEAD	1
>  
> +/* Max data object length is 2^18 dwords */
> +#define PCI_DOE_MAX_LENGTH	(1 << 18)
> +
>  /**
>   * struct pci_doe_mb - State for a single DOE mailbox
>   *
> @@ -107,6 +110,7 @@ static int pci_doe_send_req(struct pci_doe_mb *doe_mb,
>  {
>  	struct pci_dev *pdev = doe_mb->pdev;
>  	int offset = doe_mb->cap_offset;
> +	size_t length;
>  	u32 val;
>  	int i;
>  
> @@ -123,15 +127,20 @@ static int pci_doe_send_req(struct pci_doe_mb *doe_mb,
>  	if (FIELD_GET(PCI_DOE_STATUS_ERROR, val))
>  		return -EIO;
>  
> +	/* Length is 2 DW of header + length of payload in DW */
> +	length = 2 + task->request_pl_sz / sizeof(u32);
> +	if (length > PCI_DOE_MAX_LENGTH)
> +		return -EIO;
> +	if (length == PCI_DOE_MAX_LENGTH)
> +		length = 0;
> +
>  	/* Write DOE Header */
>  	val = FIELD_PREP(PCI_DOE_DATA_OBJECT_HEADER_1_VID, task->prot.vid) |
>  		FIELD_PREP(PCI_DOE_DATA_OBJECT_HEADER_1_TYPE, task->prot.type);
>  	pci_write_config_dword(pdev, offset + PCI_DOE_WRITE, val);
> -	/* Length is 2 DW of header + length of payload in DW */
>  	pci_write_config_dword(pdev, offset + PCI_DOE_WRITE,
>  			       FIELD_PREP(PCI_DOE_DATA_OBJECT_HEADER_2_LENGTH,
> -					  2 + task->request_pl_sz /
> -						sizeof(u32)));
> +					  length));
>  	for (i = 0; i < task->request_pl_sz / sizeof(u32); i++)
>  		pci_write_config_dword(pdev, offset + PCI_DOE_WRITE,
>  				       task->request_pl[i]);
> @@ -178,7 +187,10 @@ static int pci_doe_recv_resp(struct pci_doe_mb *doe_mb, struct pci_doe_task *tas
>  	pci_write_config_dword(pdev, offset + PCI_DOE_READ, 0);
>  
>  	length = FIELD_GET(PCI_DOE_DATA_OBJECT_HEADER_2_LENGTH, val);
> -	if (length > SZ_1M || length < 2)
> +	/* A value of 0x0 indicates max data object length */
> +	if (!length)
> +		length = PCI_DOE_MAX_LENGTH;
> +	if (length < 2)
>  		return -EIO;
>  
>  	/* First 2 dwords have already been read */